const method - Page 130

Undefined symbols for C++0x lambdas?

- by Austin Hyde

I was just poking around into some new stuff in C++0x, when I hit a stumbling block: #include <list> #include <cstdio> using namespace std; template <typename T,typename F> void ForEach (list<T> l, F f) { for (typename list<T>::iterator it=l.begin();it!=l.end();++it) f(*it); } int main() { int arr[] = {1,2,3,4,5,6}; list<int> l (arr,arr+6); ForEach(l,[](int x){printf("%d\n",x);}); } does not compile. I get a load of undefined symbol errors. Here's make's output: i386-apple-darwin9-gcc-4.5.0 -std=c++0x -I/usr/local/include -o func main.cpp Undefined symbols: "___cxa_rethrow", referenced from: std::_List_node<int>* std::list<int, std::allocator<int> >::_M_create_node<int const&>(int const&&&) in ccPxxPwU.o "operator new(unsigned long)", referenced from: __gnu_cxx::new_allocator<std::_List_node<int> >::allocate(unsigned long, void const*) in ccPxxPwU.o "___gxx_personality_v0", referenced from: ___gxx_personality_v0$non_lazy_ptr in ccPxxPwU.o "___cxa_begin_catch", referenced from: std::_List_node<int>* std::list<int, std::allocator<int> >::_M_create_node<int const&>(int const&&&) in ccPxxPwU.o "operator delete(void*)", referenced from: __gnu_cxx::new_allocator<std::_List_node<int> >::deallocate(std::_List_node<int>*, unsigned long) in ccPxxPwU.o "___cxa_end_catch", referenced from: std::_List_node<int>* std::list<int, std::allocator<int> >::_M_create_node<int const&>(int const&&&) in ccPxxPwU.o "std::__throw_bad_alloc()", referenced from: __gnu_cxx::new_allocator<std::_List_node<int> >::allocate(unsigned long, void const*) in ccPxxPwU.o "std::_List_node_base::_M_hook(std::_List_node_base*)", referenced from: void std::list<int, std::allocator<int> >::_M_insert<int const&>(std::_List_iterator<int>, int const&&&) in ccPxxPwU.o ld: symbol(s) not found collect2: ld returned 1 exit status make: *** [func] Error 1 Why is this not working?

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How to declare a(n) vector/array of reducer objects in Cilk++?

- by Jin

Hi All, I had a problem when I am using Cilk++, an extension to C++ for parallel computing. I found that I can't declare a vector of reducer objects: typedef cilk::reducer_opadd<int> T_reducer; vector<T_reducer> bitmiss_vec; for (int i = 0; i < 24; ++i) { T_reducer r; bitmiss_vec.push_back(r); } However, when I compile the code with Cilk++, it complains at the push_back() line: cilk++ geneAttack.cilk -O1 -g -lcilkutil -o geneAttack /usr/local/cilk/bin/../lib/gcc/x86_64-unknown-linux-gnu/4.2.4/../../../../include/cilk++/reducer_opadd.h: In member function ‘void __gnu_cxx::new_allocator<_Tp>::construct(_Tp*, const _Tp&) [with _Tp = cilk::reducer_opadd<int>]’: /usr/local/cilk/bin/../lib/gcc/x86_64-unknown-linux-gnu/4.2.4/../../../../include/c++/4.2.4/bits/stl_vector.h:601: instantiated from ‘void std::vector<_Tp, _Alloc>::push_back(const _Tp&) [with _Tp = cilk::reducer_opadd<int>, _Alloc = std::allocator<cilk::reducer_opadd<int> >]’ geneAttack.cilk:667: instantiated from here /usr/local/cilk/bin/../lib/gcc/x86_64-unknown-linux-gnu/4.2.4/../../../../include/cilk++/reducer_opadd.h:229: error: ‘cilk::reducer_opadd<Type>::reducer_opadd(const cilk::reducer_opadd<Type>&) [with Type = int]’ is private /usr/local/cilk/bin/../lib/gcc/x86_64-unknown-linux-gnu/4.2.4/../../../../include/c++/4.2.4/ext/new_allocator.h:107: error: within this context /usr/local/cilk/bin/../lib/gcc/x86_64-unknown-linux-gnu/4.2.4/../../../../include/cilk++/reducer_opadd.h: In member function ‘void std::vector<_Tp, _Alloc>::_M_insert_aux(__gnu_cxx::__normal_iterator<typename std::_Vector_base<_Tp, _Alloc>::_Tp_alloc_type::pointer, std::vector<_Tp, _Alloc> >, const _Tp&) [with _Tp = cilk::reducer_opadd<int>, _Alloc = std::allocator<cilk::reducer_opadd<int> >]’: /usr/local/cilk/bin/../lib/gcc/x86_64-unknown-linux-gnu/4.2.4/../../../../include/c++/4.2.4/bits/stl_vector.h:605: instantiated from ‘void std::vector<_Tp, _Alloc>::push_back(const _Tp&) [with _Tp = cilk::reducer_opadd<int>, _Alloc = std::allocator<cilk::reducer_opadd<int> >]’ geneAttack.cilk:667: instantiated from here /usr/local/cilk/bin/../lib/gcc/x86_64-unknown-linux-gnu/4.2.4/../../../../include/cilk++/reducer_opadd.h:229: error: ‘cilk::reducer_opadd<Type>::reducer_opadd(const cilk::reducer_opadd<Type>&) [with Type = int]’ is private /usr/local/cilk/bin/../lib/gcc/x86_64-unknown-linux-gnu/4.2.4/../../../../include/c++/4.2.4/bits/vector.tcc:252: error: within this context /usr/local/cilk/bin/../lib/gcc/x86_64-unknown-linux-gnu/4.2.4/../../../../include/c++/4.2.4/bits/stl_vector.h:605: instantiated from ‘void std::vector<_Tp, _Alloc>::push_back(const _Tp&) [with _Tp = cilk::reducer_opadd<int>, _Alloc = std::allocator<cilk::reducer_opadd<int> >]’ geneAttack.cilk:667: instantiated from here /usr/local/cilk/bin/../lib/gcc/x86_64-unknown-linux-gnu/4.2.4/../../../../include/cilk++/reducer_opadd.h:230: error: ‘cilk::reducer_opadd<Type>& cilk::reducer_opadd<Type>::operator=(const cilk::reducer_opadd<Type>&) [with Type = int]’ is private /usr/local/cilk/bin/../lib/gcc/x86_64-unknown-linux-gnu/4.2.4/../../../../include/c++/4.2.4/bits/vector.tcc:256: error: within this context /usr/local/cilk/bin/../lib/gcc/x86_64-unknown-linux-gnu/4.2.4/../../../../include/cilk++/reducer_opadd.h: In static member function ‘static _BI2 std::__copy_backward<_BoolType, std::random_access_iterator_tag>::__copy_b(_BI1, _BI1, _BI2) [with _BI1 = cilk::reducer_opadd<int>*, _BI2 = cilk::reducer_opadd<int>*, bool _BoolType = false]’: /usr/local/cilk/bin/../lib/gcc/x86_64-unknown-linux-gnu/4.2.4/../../../../include/c++/4.2.4/bits/stl_algobase.h:465: instantiated from ‘_BI2 std::__copy_backward_aux(_BI1, _BI1, _BI2) [with _BI1 = cilk::reducer_opadd<int>*, _BI2 = cilk::reducer_opadd<int>*]’ /usr/local/cilk/bin/../lib/gcc/x86_64-unknown-linux-gnu/4.2.4/../../../../include/c++/4.2.4/bits/stl_algobase.h:474: instantiated from ‘static _BI2 std::__copy_backward_normal<<anonymous>, <anonymous> >::__copy_b_n(_BI1, _BI1, _BI2) [with _BI1 = cilk::reducer_opadd<int>*, _BI2 = cilk::reducer_opadd<int>*, bool <anonymous> = false, bool <anonymous> = false]’ /usr/local/cilk/bin/../lib/gcc/x86_64-unknown-linux-gnu/4.2.4/../../../../include/c++/4.2.4/bits/stl_algobase.h:540: instantiated from ‘_BI2 std::copy_backward(_BI1, _BI1, _BI2) [with _BI1 = cilk::reducer_opadd<int>*, _BI2 = cilk::reducer_opadd<int>*]’ /usr/local/cilk/bin/../lib/gcc/x86_64-unknown-linux-gnu/4.2.4/../../../../include/c++/4.2.4/bits/vector.tcc:253: instantiated from ‘void std::vector<_Tp, _Alloc>::_M_insert_aux(__gnu_cxx::__normal_iterator<typename std::_Vector_base<_Tp, _Alloc>::_Tp_alloc_type::pointer, std::vector<_Tp, _Alloc> >, const _Tp&) [with _Tp = cilk::reducer_opadd<int>, _Alloc = std::allocator<cilk::reducer_opadd<int> >]’ /usr/local/cilk/bin/../lib/gcc/x86_64-unknown-linux-gnu/4.2.4/../../../../include/c++/4.2.4/bits/stl_vector.h:605: instantiated from ‘void std::vector<_Tp, _Alloc>::push_back(const _Tp&) [with _Tp = cilk::reducer_opadd<int>, _Alloc = std::allocator<cilk::reducer_opadd<int> >]’ geneAttack.cilk:667: instantiated from here /usr/local/cilk/bin/../lib/gcc/x86_64-unknown-linux-gnu/4.2.4/../../../../include/cilk++/reducer_opadd.h:230: error: ‘cilk::reducer_opadd<Type>& cilk::reducer_opadd<Type>::operator=(const cilk::reducer_opadd<Type>&) [with Type = int]’ is private /usr/local/cilk/bin/../lib/gcc/x86_64-unknown-linux-gnu/4.2.4/../../../../include/c++/4.2.4/bits/stl_algobase.h:433: error: within this context /usr/local/cilk/bin/../lib/gcc/x86_64-unknown-linux-gnu/4.2.4/../../../../include/cilk++/reducer_opadd.h: In function ‘void std::_Construct(_T1*, const _T2&) [with _T1 = cilk::reducer_opadd<int>, _T2 = cilk::reducer_opadd<int>]’: /usr/local/cilk/bin/../lib/gcc/x86_64-unknown-linux-gnu/4.2.4/../../../../include/c++/4.2.4/bits/stl_uninitialized.h:87: instantiated from ‘_ForwardIterator std::__uninitialized_copy_aux(_InputIterator, _InputIterator, _ForwardIterator, std::__false_type) [with _InputIterator = cilk::reducer_opadd<int>*, _ForwardIterator = cilk::reducer_opadd<int>*]’ /usr/local/cilk/bin/../lib/gcc/x86_64-unknown-linux-gnu/4.2.4/../../../../include/c++/4.2.4/bits/stl_uninitialized.h:114: instantiated from ‘_ForwardIterator std::uninitialized_copy(_InputIterator, _InputIterator, _ForwardIterator) [with _InputIterator = cilk::reducer_opadd<int>*, _ForwardIterator = cilk::reducer_opadd<int>*]’ /usr/local/cilk/bin/../lib/gcc/x86_64-unknown-linux-gnu/4.2.4/../../../../include/c++/4.2.4/bits/stl_uninitialized.h:254: instantiated from ‘_ForwardIterator std::__uninitialized_copy_a(_InputIterator, _InputIterator, _ForwardIterator, std::allocator<_Tp>) [with _InputIterator = cilk::reducer_opadd<int>*, _ForwardIterator = cilk::reducer_opadd<int>*, _Tp = cilk::reducer_opadd<int>]’ /usr/local/cilk/bin/../lib/gcc/x86_64-unknown-linux-gnu/4.2.4/../../../../include/c++/4.2.4/bits/vector.tcc:275: instantiated from ‘void std::vector<_Tp, _Alloc>::_M_insert_aux(__gnu_cxx::__normal_iterator<typename std::_Vector_base<_Tp, _Alloc>::_Tp_alloc_type::pointer, std::vector<_Tp, _Alloc> >, const _Tp&) [with _Tp = cilk::reducer_opadd<int>, _Alloc = std::allocator<cilk::reducer_opadd<int> >]’ /usr/local/cilk/bin/../lib/gcc/x86_64-unknown-linux-gnu/4.2.4/../../../../include/c++/4.2.4/bits/stl_vector.h:605: instantiated from ‘void std::vector<_Tp, _Alloc>::push_back(const _Tp&) [with _Tp = cilk::reducer_opadd<int>, _Alloc = std::allocator<cilk::reducer_opadd<int> >]’ geneAttack.cilk:667: instantiated from here /usr/local/cilk/bin/../lib/gcc/x86_64-unknown-linux-gnu/4.2.4/../../../../include/cilk++/reducer_opadd.h:229: error: ‘cilk::reducer_opadd<Type>::reducer_opadd(const cilk::reducer_opadd<Type>&) [with Type = int]’ is private /usr/local/cilk/bin/../lib/gcc/x86_64-unknown-linux-gnu/4.2.4/../../../../include/c++/4.2.4/bits/stl_construct.h:81: error: within this context make: *** [geneAttack] Error 1 jinchen@galactica:~/workspace/biometrics/genAttack$ make cilk++ geneAttack.cilk -O1 -g -lcilkutil -o geneAttack geneAttack.cilk: In function ‘int cilk cilk_main(int, char**)’: geneAttack.cilk:670: error: expected primary-expression before ‘,’ token geneAttack.cilk:670: error: expected primary-expression before ‘}’ token geneAttack.cilk:674: error: ‘bitmiss_vec’ was not declared in this scope make: *** [geneAttack] Error 1 The Cilk++ manule says it supports array/vector of reducers, although there are performance issues to consider: "If you create a large number of reducers (for example, an array or vector of reducers) you must be aware that there is an overhead at steal and reduce that is proportional to the number of reducers in the program. " Anyone knows what is going on? How should I declare/use vector of reducers? Thank you

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How to develop asp.net web service to create the web method which can take the parameter of type win

- by Shailesh Jaiswal

I am developing asp.net web service. I am developing this web service so that OPC ( OLE for process control) client application can use it. In this web service I am using the built-in functions provided by the namespaces using OPC, using OPCDA, using OPCDA.NET. I have also added the namespace using System.Windows.Forms in this web service so that I can use the windows form control. In that we service I have created on web method which takes the parameter of type windows form control as given below. public void getOPCServerItems(TreeView tvServerItems, ListView lvBranchItems) { ArrayList ArrlstObj = new ArrayList(); ItemShowTreeList = OpcSrv.ShowBrowseTreeList(tvServerItems, lvBranchItems); ItemShowTreeList.BrowseModeOneLevel = true; // browse hierachy levels when selected. (default) ItemShowTreeList.Show(OpcSrv.ServerName); } In the above web method I need to pass the values to the built-in function ShowBrowseTreeList() (found in OPC, OPCDA, OPCDA.NET namespaces). This function takes the two parameter of windows form control type. These parameters are Treeview & ListView control of the windows form. In the above web method ShowBrowseTreeList() method automatically create the treeview & listview structure of the available items. Now as I am consuming the web service so I need to pass the values to the webmethod getOPCServerItems(). But as I my consuming application is asp.net application there is no such windows form control. In asp.net application there are also & control. I want to display The data returned in these asp.net controls rather than windows form control. I am not getting the way what should I need to do or how should I pass the values form my client application to this web service ? In the above method getOPCServerItems() when I use the parameter of type treeview & listview it generate s error "Cannot serialize member System.ComponentModel.Component.Site of type System.ComponentModel.ISite because it is an interface.". Can you provide me the the way In which I can write the above web method & how should I pass parameter to the Treeview & Listview control (windows form control) from my asp.net application ? which controls I should use to pass parameters ? Is there any need to do any type of casting ? Can you provide me the the code for above web method so that I can resolve the above issue ?

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Where is the method call in the EXE file?

- by Victor Hurdugaci

Introduction After watching this video from LIDNUG, about .NET code protection http://secureteam.net/lidnug_recording/Untitled.swf (especially from 46:30 to 57:30), I would to locate the call to a MessageBox.Show in an EXE I created. The only logic in my "TrialApp.exe" is: public partial class Form1 : Form { public Form1() { InitializeComponent(); } private void Form1_Load(object sender, EventArgs e) { MessageBox.Show("This is trial app"); } } Compiled on the Release configuration: http://rapidshare.com/files/392503054/TrialApp.exe.html What I do to locate the call Run the application in WinDBG and break after the message box appears. Get the CLR stack with !clrstack: 0040e840 5e21350b [InlinedCallFrame: 0040e840] System.Windows.Forms.SafeNativeMethods.MessageBox(System.Runtime.InteropServices.HandleRef, System.String, System.String, Int32) 0040e894 5e21350b System.Windows.Forms.MessageBox.ShowCore(System.Windows.Forms.IWin32Window, System.String, System.String, System.Windows.Forms.MessageBoxButtons, System.Windows.Forms.MessageBoxIcon, System.Windows.Forms.MessageBoxDefaultButton, System.Windows.Forms.MessageBoxOptions, Boolean) 0040e898 002701f0 [InlinedCallFrame: 0040e898] 0040e934 002701f0 TrialApp.Form1.Form1_Load(System.Object, System.EventArgs) Get the MethodDesc structure (using the address of Form1_Load) !ip2md 002701f0 MethodDesc: 001762f8 Method Name: TrialApp.Form1.Form1_Load(System.Object, System.EventArgs) Class: 00171678 MethodTable: 00176354 mdToken: 06000005 Module: 00172e9c IsJitted: yes CodeAddr: 002701d0 Transparency: Critical Source file: D:\temp\TrialApp\TrialApp\Form1.cs @ 22 Dump the IL of this method (by MethodDesc) !dumpil 001762f8 IL_0000: ldstr "This is trial app" IL_0005: call System.Windows.Forms.MessageBox::Show IL_000a: pop IL_000b: ret So, as the video mentioned, the call to to Show is 5 bytes from the beginning of the method implementation. Now I open CFFExplorer (just like in the video) and get the RVA of the Form1_Load method: 00002083. After this, I go to Address Converter (again in CFF Explorer) and navigate to offset 00002083. There we have: 32 72 01 00 00 70 28 16 00 00 0A 26 2A 7A 03 2C 13 02 7B 02 00 00 04 2C 0B 02 7B 02 00 00 04 6F 17 00 00 0A 02 03 28 18 00 00 0A 2A 00 03 30 04 00 67 00 00 00 00 00 00 00 02 28 19 00 00 0A 02 In the video is mentioned that the first 12 bytes are for the method header so I skip them 2A 7A 03 2C 13 02 7B 02 00 00 04 2C 0B 02 7B 02 00 00 04 6F 17 00 00 0A 02 03 28 18 00 00 0A 2A 00 03 30 04 00 67 00 00 00 00 00 00 00 02 28 19 00 00 0A 02 5 bytes from the beginning of the implementation should be the opcode for method call (28). Unfortunately, is not there. 02 7B 02 00 00 04 2C 0B 02 7B 02 00 00 04 6F 17 00 00 0A 02 03 28 18 00 00 0A 2A 00 03 30 04 00 67 00 00 00 00 00 00 00 02 28 19 00 00 0A 02 Questions: What am I doing wrong? Why there is no method call at that position in the file? Or maybe the video is missing some information... Why the guy in that video replaces the call with 9 zeros?

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How to declare a vector or array of reducer objects in Cilk++?

- by Jin

Hi All, I had a problem when I am using Cilk++, an extension to C++ for parallel computing. I found that I can't declare a vector of reducer objects: typedef cilk::reducer_opadd<int> T_reducer; vector<T_reducer> bitmiss_vec; for (int i = 0; i < 24; ++i) { T_reducer r; bitmiss_vec.push_back(r); } However, when I compile the code with Cilk++, it complains at the push_back() line: cilk++ geneAttack.cilk -O1 -g -lcilkutil -o geneAttack /usr/local/cilk/bin/../lib/gcc/x86_64-unknown-linux-gnu/4.2.4/../../../../include/cilk++/reducer_opadd.h: In member function ‘void __gnu_cxx::new_allocator<_Tp>::construct(_Tp*, const _Tp&) [with _Tp = cilk::reducer_opadd<int>]’: /usr/local/cilk/bin/../lib/gcc/x86_64-unknown-linux-gnu/4.2.4/../../../../include/c++/4.2.4/bits/stl_vector.h:601: instantiated from ‘void std::vector<_Tp, _Alloc>::push_back(const _Tp&) [with _Tp = cilk::reducer_opadd<int>, _Alloc = std::allocator<cilk::reducer_opadd<int> >]’ geneAttack.cilk:667: instantiated from here /usr/local/cilk/bin/../lib/gcc/x86_64-unknown-linux-gnu/4.2.4/../../../../include/cilk++/reducer_opadd.h:229: error: ‘cilk::reducer_opadd<Type>::reducer_opadd(const cilk::reducer_opadd<Type>&) [with Type = int]’ is private /usr/local/cilk/bin/../lib/gcc/x86_64-unknown-linux-gnu/4.2.4/../../../../include/c++/4.2.4/ext/new_allocator.h:107: error: within this context /usr/local/cilk/bin/../lib/gcc/x86_64-unknown-linux-gnu/4.2.4/../../../../include/cilk++/reducer_opadd.h: In member function ‘void std::vector<_Tp, _Alloc>::_M_insert_aux(__gnu_cxx::__normal_iterator<typename std::_Vector_base<_Tp, _Alloc>::_Tp_alloc_type::pointer, std::vector<_Tp, _Alloc> >, const _Tp&) [with _Tp = cilk::reducer_opadd<int>, _Alloc = std::allocator<cilk::reducer_opadd<int> >]’: /usr/local/cilk/bin/../lib/gcc/x86_64-unknown-linux-gnu/4.2.4/../../../../include/c++/4.2.4/bits/stl_vector.h:605: instantiated from ‘void std::vector<_Tp, _Alloc>::push_back(const _Tp&) [with _Tp = cilk::reducer_opadd<int>, _Alloc = std::allocator<cilk::reducer_opadd<int> >]’ geneAttack.cilk:667: instantiated from here /usr/local/cilk/bin/../lib/gcc/x86_64-unknown-linux-gnu/4.2.4/../../../../include/cilk++/reducer_opadd.h:229: error: ‘cilk::reducer_opadd<Type>::reducer_opadd(const cilk::reducer_opadd<Type>&) [with Type = int]’ is private /usr/local/cilk/bin/../lib/gcc/x86_64-unknown-linux-gnu/4.2.4/../../../../include/c++/4.2.4/bits/vector.tcc:252: error: within this context /usr/local/cilk/bin/../lib/gcc/x86_64-unknown-linux-gnu/4.2.4/../../../../include/c++/4.2.4/bits/stl_vector.h:605: instantiated from ‘void std::vector<_Tp, _Alloc>::push_back(const _Tp&) [with _Tp = cilk::reducer_opadd<int>, _Alloc = std::allocator<cilk::reducer_opadd<int> >]’ geneAttack.cilk:667: instantiated from here /usr/local/cilk/bin/../lib/gcc/x86_64-unknown-linux-gnu/4.2.4/../../../../include/cilk++/reducer_opadd.h:230: error: ‘cilk::reducer_opadd<Type>& cilk::reducer_opadd<Type>::operator=(const cilk::reducer_opadd<Type>&) [with Type = int]’ is private /usr/local/cilk/bin/../lib/gcc/x86_64-unknown-linux-gnu/4.2.4/../../../../include/c++/4.2.4/bits/vector.tcc:256: error: within this context /usr/local/cilk/bin/../lib/gcc/x86_64-unknown-linux-gnu/4.2.4/../../../../include/cilk++/reducer_opadd.h: In static member function ‘static _BI2 std::__copy_backward<_BoolType, std::random_access_iterator_tag>::__copy_b(_BI1, _BI1, _BI2) [with _BI1 = cilk::reducer_opadd<int>*, _BI2 = cilk::reducer_opadd<int>*, bool _BoolType = false]’: /usr/local/cilk/bin/../lib/gcc/x86_64-unknown-linux-gnu/4.2.4/../../../../include/c++/4.2.4/bits/stl_algobase.h:465: instantiated from ‘_BI2 std::__copy_backward_aux(_BI1, _BI1, _BI2) [with _BI1 = cilk::reducer_opadd<int>*, _BI2 = cilk::reducer_opadd<int>*]’ /usr/local/cilk/bin/../lib/gcc/x86_64-unknown-linux-gnu/4.2.4/../../../../include/c++/4.2.4/bits/stl_algobase.h:474: instantiated from ‘static _BI2 std::__copy_backward_normal<<anonymous>, <anonymous> >::__copy_b_n(_BI1, _BI1, _BI2) [with _BI1 = cilk::reducer_opadd<int>*, _BI2 = cilk::reducer_opadd<int>*, bool <anonymous> = false, bool <anonymous> = false]’ /usr/local/cilk/bin/../lib/gcc/x86_64-unknown-linux-gnu/4.2.4/../../../../include/c++/4.2.4/bits/stl_algobase.h:540: instantiated from ‘_BI2 std::copy_backward(_BI1, _BI1, _BI2) [with _BI1 = cilk::reducer_opadd<int>*, _BI2 = cilk::reducer_opadd<int>*]’ /usr/local/cilk/bin/../lib/gcc/x86_64-unknown-linux-gnu/4.2.4/../../../../include/c++/4.2.4/bits/vector.tcc:253: instantiated from ‘void std::vector<_Tp, _Alloc>::_M_insert_aux(__gnu_cxx::__normal_iterator<typename std::_Vector_base<_Tp, _Alloc>::_Tp_alloc_type::pointer, std::vector<_Tp, _Alloc> >, const _Tp&) [with _Tp = cilk::reducer_opadd<int>, _Alloc = std::allocator<cilk::reducer_opadd<int> >]’ /usr/local/cilk/bin/../lib/gcc/x86_64-unknown-linux-gnu/4.2.4/../../../../include/c++/4.2.4/bits/stl_vector.h:605: instantiated from ‘void std::vector<_Tp, _Alloc>::push_back(const _Tp&) [with _Tp = cilk::reducer_opadd<int>, _Alloc = std::allocator<cilk::reducer_opadd<int> >]’ geneAttack.cilk:667: instantiated from here /usr/local/cilk/bin/../lib/gcc/x86_64-unknown-linux-gnu/4.2.4/../../../../include/cilk++/reducer_opadd.h:230: error: ‘cilk::reducer_opadd<Type>& cilk::reducer_opadd<Type>::operator=(const cilk::reducer_opadd<Type>&) [with Type = int]’ is private /usr/local/cilk/bin/../lib/gcc/x86_64-unknown-linux-gnu/4.2.4/../../../../include/c++/4.2.4/bits/stl_algobase.h:433: error: within this context /usr/local/cilk/bin/../lib/gcc/x86_64-unknown-linux-gnu/4.2.4/../../../../include/cilk++/reducer_opadd.h: In function ‘void std::_Construct(_T1*, const _T2&) [with _T1 = cilk::reducer_opadd<int>, _T2 = cilk::reducer_opadd<int>]’: /usr/local/cilk/bin/../lib/gcc/x86_64-unknown-linux-gnu/4.2.4/../../../../include/c++/4.2.4/bits/stl_uninitialized.h:87: instantiated from ‘_ForwardIterator std::__uninitialized_copy_aux(_InputIterator, _InputIterator, _ForwardIterator, std::__false_type) [with _InputIterator = cilk::reducer_opadd<int>*, _ForwardIterator = cilk::reducer_opadd<int>*]’ /usr/local/cilk/bin/../lib/gcc/x86_64-unknown-linux-gnu/4.2.4/../../../../include/c++/4.2.4/bits/stl_uninitialized.h:114: instantiated from ‘_ForwardIterator std::uninitialized_copy(_InputIterator, _InputIterator, _ForwardIterator) [with _InputIterator = cilk::reducer_opadd<int>*, _ForwardIterator = cilk::reducer_opadd<int>*]’ /usr/local/cilk/bin/../lib/gcc/x86_64-unknown-linux-gnu/4.2.4/../../../../include/c++/4.2.4/bits/stl_uninitialized.h:254: instantiated from ‘_ForwardIterator std::__uninitialized_copy_a(_InputIterator, _InputIterator, _ForwardIterator, std::allocator<_Tp>) [with _InputIterator = cilk::reducer_opadd<int>*, _ForwardIterator = cilk::reducer_opadd<int>*, _Tp = cilk::reducer_opadd<int>]’ /usr/local/cilk/bin/../lib/gcc/x86_64-unknown-linux-gnu/4.2.4/../../../../include/c++/4.2.4/bits/vector.tcc:275: instantiated from ‘void std::vector<_Tp, _Alloc>::_M_insert_aux(__gnu_cxx::__normal_iterator<typename std::_Vector_base<_Tp, _Alloc>::_Tp_alloc_type::pointer, std::vector<_Tp, _Alloc> >, const _Tp&) [with _Tp = cilk::reducer_opadd<int>, _Alloc = std::allocator<cilk::reducer_opadd<int> >]’ /usr/local/cilk/bin/../lib/gcc/x86_64-unknown-linux-gnu/4.2.4/../../../../include/c++/4.2.4/bits/stl_vector.h:605: instantiated from ‘void std::vector<_Tp, _Alloc>::push_back(const _Tp&) [with _Tp = cilk::reducer_opadd<int>, _Alloc = std::allocator<cilk::reducer_opadd<int> >]’ geneAttack.cilk:667: instantiated from here /usr/local/cilk/bin/../lib/gcc/x86_64-unknown-linux-gnu/4.2.4/../../../../include/cilk++/reducer_opadd.h:229: error: ‘cilk::reducer_opadd<Type>::reducer_opadd(const cilk::reducer_opadd<Type>&) [with Type = int]’ is private /usr/local/cilk/bin/../lib/gcc/x86_64-unknown-linux-gnu/4.2.4/../../../../include/c++/4.2.4/bits/stl_construct.h:81: error: within this context make: *** [geneAttack] Error 1 jinchen@galactica:~/workspace/biometrics/genAttack$ make cilk++ geneAttack.cilk -O1 -g -lcilkutil -o geneAttack geneAttack.cilk: In function ‘int cilk cilk_main(int, char**)’: geneAttack.cilk:670: error: expected primary-expression before ‘,’ token geneAttack.cilk:670: error: expected primary-expression before ‘}’ token geneAttack.cilk:674: error: ‘bitmiss_vec’ was not declared in this scope make: *** [geneAttack] Error 1 The Cilk++ manule says it supports array/vector of reducers, although there are performance issues to consider: "If you create a large number of reducers (for example, an array or vector of reducers) you must be aware that there is an overhead at steal and reduce that is proportional to the number of reducers in the program. " Anyone knows what is going on? How should I declare/use vector of reducers? Thank you

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Can I call make runtime decided method calls in Java?

- by Catalin Marin

I know there is an invoke function that does the stuff, I am overall interested in the "correctness" of using such a behavior. My issue is this: I have a Service Object witch contains methods which I consider services. What I want to do is alter the behavior of those services without later intrusion. For example: class MyService { public ServiceResponse ServeMeDonuts() { do stuff... return new ServiceResponse(); } after 2 months I find out that I need to offer the same service to a new client app and I also need to do certain extra stuff like setting a flag, or make or updating certain data, or encode the response differently. What I can do is pop it up and throw down some IFs. In my opinion this is not good as it means interaction with tested code and may result in un wanted behaviour for the previous service clients. So I come and add something to my registry telling the system that the "NewClient" has a different behavior. So I'll do something like this: public interface Behavior { public void preExecute(); public void postExecute(); } public class BehaviorOfMyService implements Behavior{ String method; String clientType; public void BehaviorOfMyService(String method,String clientType) { this.method = method; this.clientType = clientType; } public void preExecute() { Method preCall = this.getClass().getMethod("pre" + this.method + this.clientType); if(preCall != null) { return preCall.invoke(); } return false; } ...same for postExecute(); public void preServeMeDonutsNewClient() { do the stuff... } } when the system will do something like this if(registrySaysThereIs different behavior set for this ServiceObject) { Class toBeCalled = Class.forName("BehaviorOf" + usedServiceObjectName); Object instance = toBeCalled.getConstructor().newInstance(method,client); instance.preExecute(); ....call the service... instance.postExecute(); .... } I am not particularly interested in correctness of code as in correctness of thinking and approach. Actually I have to do this in PHP, witch I see as a kind of Pop music of programming which I have to "sing" for commercial reasons, even though I play POP I really want to sing by the book, so putting aside my more or less inspired analogy I really want to know your opinion on this matter for it's practical necessity and technical approach. Thanks

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QTreeView memory consumption

- by Eye of Hell

Hello. I'm testing QTreeView functionality right now, and i was amazed by one thing. It seems that QTreeView memory consumption depends on items count O_O. This is highly unusual, since model-view containers of such type only keeps track for items being displayed, and rest of items are in the model. I have written a following code with a simple model that holds no data and just reports that it has 10 millions items. With MFC, Windows API or .NET tree / list with such model will take no memory, since it will display only 10-20 visible elements and will request model for more upon scrolling / expanding items. But with Qt, such simple model results in ~300Mb memory consumtion. Increasing number of items will increase memory consumption. Maybe anyone can hint me what i'm doing wrong? :) #include <QtGui/QApplication> #include <QTreeView> #include <QAbstractItemModel> class CModel : public QAbstractItemModel { public: QModelIndex index ( int i_nRow, int i_nCol, const QModelIndex& i_oParent = QModelIndex() ) const { return createIndex( i_nRow, i_nCol, 0 ); } public: QModelIndex parent ( const QModelIndex& i_oInex ) const { return QModelIndex(); } public: int rowCount ( const QModelIndex& i_oParent = QModelIndex() ) const { return i_oParent.isValid() ? 0 : 1000 * 1000 * 10; } public: int columnCount ( const QModelIndex& i_oParent = QModelIndex() ) const { return 1; } public: QVariant data ( const QModelIndex& i_oIndex, int i_nRole = Qt::DisplayRole ) const { return Qt::DisplayRole == i_nRole ? QVariant( "1" ) : QVariant(); } }; int main(int argc, char *argv[]) { QApplication a(argc, argv); QTreeView oWnd; CModel oModel; oWnd.setUniformRowHeights( true ); oWnd.setModel( & oModel ); oWnd.show(); return a.exec(); }

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templates and casting operators

- by Jonathan Swinney

This code compiles in CodeGear 2009 and Visual Studio 2010 but not gcc. Why? class Foo { public: operator int() const; template <typename T> T get() const { return this->operator T(); } }; Foo::operator int() const { return 5; } The error message is: test.cpp: In member function `T Foo::get() const': test.cpp:6: error: 'const class Foo' has no member named 'operator T'

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How to declare ASP classic constants to a data type?

- by Guy

In asp classic and vbscript, you can declare a Const with a hexidecial value, and a date type value: Const C_LIGHTCYAN = &hCCFFEE Const C_STARTDATE = #1 JAN 2000# But how can I declare currency, single or doubles data types? Const C_LONG = 1024 '# I want this to be a LONG, not an INT! I'm sure I've seen something like Const C_LNG = L12345 or some other prefix/suffix combination for longs or doubles but can't find the source now

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Header Guard Issues - Getting Swallowed Alive

- by gjnave

I'm totally at wit's end: I can't figure out how my dependency issues. I've read countless posts and blogs and reworked my code so many times that I can't even remember what almost worked and what didnt. I continually get not only redefinition errors, but class not defined errors. I rework the header guards and remove some errors simply to find others. I somehow got everything down to one error but then even that got broke while trying to fix it. Would you please help me figure out the problem? card.cpp #include <iostream> #include <cctype> #include "card.h" using namespace std; // ====DECL====== Card::Card() { abilities = 0; flavorText = 0; keywords = 0; artifact = 0; classType = new char[strlen("Card") + 1]; classType = "Card"; } Card::~Card (){ delete name; delete abilities; delete flavorText; artifact = NULL; } // ------------ Card::Card(const Card & to_copy) { name = new char[strlen(to_copy.name) +1]; // creating dynamic array strcpy(to_copy.name, name); type = to_copy.type; color = to_copy.color; manaCost = to_copy.manaCost; abilities = new char[strlen(to_copy.abilities) +1]; strcpy(abilities, to_copy.abilities); flavorText = new char[strlen(to_copy.flavorText) +1]; strcpy(flavorText, to_copy.flavorText); keywords = new char[strlen(to_copy.keywords) +1]; strcpy(keywords, to_copy.keywords); inPlay = to_copy.inPlay; tapped = to_copy.tapped; enchanted = to_copy.enchanted; cursed = to_copy.cursed; if (to_copy.type != ARTIFACT) artifact = to_copy.artifact; } // ====DECL===== int Card::equipArtifact(Artifact* to_equip){ artifact = to_equip; } Artifact * Card::unequipArtifact(Card * unequip_from){ Artifact * to_remove = artifact; artifact = NULL; return to_remove; // put card in hand or in graveyard } int Card::enchant( Card * to_enchant){ to_enchant->enchanted = true; cout << "enchanted" << endl; } int Card::disenchant( Card * to_disenchant){ to_disenchant->enchanted = false; cout << "Enchantment Removed" << endl; } // ========DECL===== Spell::Spell() { currPower = basePower; currToughness = baseToughness; classType = new char[strlen("Spell") + 1]; classType = "Spell"; } Spell::~Spell(){} // --------------- Spell::Spell(const Spell & to_copy){ currPower = to_copy.currPower; basePower = to_copy.basePower; currToughness = to_copy.currToughness; baseToughness = to_copy.baseToughness; } // ========= int Spell::attack( Spell *& blocker ){ blocker->currToughness -= currPower; currToughness -= blocker->currToughness; } //========== int Spell::counter (Spell *& to_counter){ cout << to_counter->name << " was countered by " << name << endl; } // ============ int Spell::heal (Spell *& to_heal, int amountOfHealth){ to_heal->currToughness += amountOfHealth; } // ------- Creature::Creature(){ summoningSick = true; } // =====DECL====== Land::Land(){ color = NON; classType = new char[strlen("Land") + 1]; classType = "Land"; } // ------ int Land::generateMana(int mana){ // ... // } card.h #ifndef CARD_H #define CARD_H #include <cctype> #include <iostream> #include "conception.h" class Artifact; class Spell; class Card : public Conception { public: Card(); Card(const Card &); ~Card(); protected: char* name; enum CardType { INSTANT, CREATURE, LAND, ENCHANTMENT, ARTIFACT, PLANESWALKER}; enum CardColor { WHITE, BLUE, BLACK, RED, GREEN, NON }; CardType type; CardColor color; int manaCost; char* abilities; char* flavorText; char* keywords; bool inPlay; bool tapped; bool cursed; bool enchanted; Artifact* artifact; virtual int enchant( Card * ); virtual int disenchant (Card * ); virtual int equipArtifact( Artifact* ); virtual Artifact* unequipArtifact(Card * ); }; // ------------ class Spell: public Card { public: Spell(); ~Spell(); Spell(const Spell &); protected: virtual int heal( Spell *&, int ); virtual int attack( Spell *& ); virtual int counter( Spell*& ); int currToughness; int baseToughness; int currPower; int basePower; }; class Land: public Card { public: Land(); ~Land(); protected: virtual int generateMana(int); }; class Forest: public Land { public: Forest(); ~Forest(); protected: int generateMana(); }; class Creature: public Spell { public: Creature(); ~Creature(); protected: bool summoningSick; }; class Sorcery: public Spell { public: Sorcery(); ~Sorcery(); protected: }; #endif conception.h -- this is an "uber class" from which everything derives class Conception{ public: Conception(); ~Conception(); protected: char* classType; }; conception.cpp Conception::Conception{ Conception(){ classType = new char[11]; char = "Conception"; } game.cpp -- this is an incomplete class as of this code #include <iostream> #include <cctype> #include "game.h" #include "player.h" Battlefield::Battlefield(){ card = 0; } Battlefield::~Battlefield(){ delete card; } Battlefield::Battlefield(const Battlefield & to_copy){ } // =========== /* class Game(){ public: Game(); ~Game(); protected: Player** player; // for multiple players Battlefield* root; // for battlefield getPlayerMove(); // ask player what to do addToBattlefield(); removeFromBattlefield(); sendAttack(); } */ #endif game.h #ifndef GAME_H #define GAME_H #include "list.h" class CardList(); class Battlefield : CardList{ public: Battlefield(); ~Battlefield(); protected: Card* card; // make an array }; class Game : Conception{ public: Game(); ~Game(); protected: Player** player; // for multiple players Battlefield* root; // for battlefield getPlayerMove(); // ask player what to do addToBattlefield(); removeFromBattlefield(); sendAttack(); Battlefield* field; }; list.cpp #include <iostream> #include <cctype> #include "list.h" // ========== LinkedList::LinkedList(){ root = new Node; classType = new char[strlen("LinkedList") + 1]; classType = "LinkedList"; }; LinkedList::~LinkedList(){ delete root; } LinkedList::LinkedList(const LinkedList & obj) { // code to copy } // --------- // ========= int LinkedList::delete_all(Node* root){ if (root = 0) return 0; delete_all(root->next); root = 0; } int LinkedList::add( Conception*& is){ if (root == 0){ root = new Node; root->next = 0; } else { Node * curr = root; root = new Node; root->next=curr; root->it = is; } } int LinkedList::remove(Node * root, Node * prev, Conception* is){ if (root = 0) return -1; if (root->it == is){ root->next = root->next; return 0; } remove(root->next, root, is); return 0; } Conception* LinkedList::find(Node*& root, const Conception* is, Conception* holder = NULL) { if (root==0) return NULL; if (root->it == is){ return root-> it; } holder = find(root->next, is); return holder; } Node* LinkedList::goForward(Node * root){ if (root==0) return root; if (root->next == 0) return root; else return root->next; } // ============ Node* LinkedList::goBackward(Node * root){ root = root->prev; } list.h #ifndef LIST_H #define LIST_H #include <iostream> #include "conception.h" class Node : public Conception { public: Node() : next(0), prev(0), it(0) { it = 0; classType = new char[strlen("Node") + 1]; classType = "Node"; }; ~Node(){ delete it; delete next; delete prev; } Node* next; Node* prev; Conception* it; // generic object }; // ---------------------- class LinkedList : public Conception { public: LinkedList(); ~LinkedList(); LinkedList(const LinkedList&); friend bool operator== (Conception& thing_1, Conception& thing_2 ); protected: virtual int delete_all(Node*); virtual int add( Conception*& ); // virtual Conception* find(Node *&, const Conception*, Conception* ); // virtual int remove( Node *, Node *, Conception* ); // removes question with keyword int display_all(node*& ); virtual Node* goForward(Node *); virtual Node* goBackward(Node *); Node* root; // write copy constrcutor }; // ============= class CircularLinkedList : public LinkedList { public: // CircularLinkedList(); // ~CircularLinkedList(); // CircularLinkedList(const CircularLinkedList &); }; class DoubleLinkedList : public LinkedList { public: // DoubleLinkedList(); // ~DoubleLinkedList(); // DoubleLinkedList(const DoubleLinkedList &); protected: }; // END OF LIST Hierarchy #endif player.cpp #include <iostream> #include "player.h" #include "list.h" using namespace std; Library::Library(){ root = 0; } Library::~Library(){ delete card; } // ====DECL========= Player::~Player(){ delete fname; delete lname; delete deck; } Wizard::~Wizard(){ delete mana; delete rootL; delete rootH; } // =====Player====== void Player::changeName(const char[] first, const char[] last){ char* backup1 = new char[strlen(fname) + 1]; strcpy(backup1, fname); char* backup2 = new char[strlen(lname) + 1]; strcpy(backup1, lname); if (first != NULL){ fname = new char[strlen(first) +1]; strcpy(fname, first); } if (last != NULL){ lname = new char[strlen(last) +1]; strcpy(lname, last); } return 0; } // ========== void Player::seeStats(Stats*& to_put){ to_put->wins = stats->wins; to_put->losses = stats->losses; to_put->winRatio = stats->winRatio; } // ---------- void Player::displayDeck(const LinkedList* deck){ } // ================ void CardList::findCard(Node* root, int id, NodeCard*& is){ if (root == NULL) return; if (root->it.id == id){ copyCard(root->it, is); return; } else findCard(root->next, id, is); } // -------- void CardList::deleteAll(Node* root){ if (root == NULL) return; deleteAll(root->next); root->next = NULL; } // --------- void CardList::removeCard(Node* root, int id){ if (root == NULL) return; if (root->id = id){ root->prev->next = root->next; // the prev link of root, looks back to next of prev node, and sets to where root next is pointing } return; } // --------- void CardList::addCard(Card* to_add){ if (!root){ root = new Node; root->next = NULL; root->prev = NULL; root->it = &to_add; return; } else { Node* original = root; root = new Node; root->next = original; root->prev = NULL; original->prev = root; } } // ----------- void CardList::displayAll(Node*& root){ if (root == NULL) return; cout << "Card Name: " << root->it.cardName; cout << " || Type: " << root->it.type << endl; cout << " --------------- " << endl; if (root->classType == "Spell"){ cout << "Base Power: " << root->it.basePower; cout << " || Current Power: " << root->it.currPower << endl; cout << "Base Toughness: " << root->it.baseToughness; cout << " || Current Toughness: " << root->it.currToughness << endl; } cout << "Card Type: " << root->it.currPower; cout << " || Card Color: " << root->it.color << endl; cout << "Mana Cost" << root->it.manaCost << endl; cout << "Keywords: " << root->it.keywords << endl; cout << "Flavor Text: " << root->it.flavorText << endl; cout << " ----- Class Type: " << root->it.classType << " || ID: " << root->it.id << " ----- " << endl; cout << " ******************************************" << endl; cout << endl; // ------- void CardList::copyCard(const Card& to_get, Card& put_to){ put_to.type = to_get.type; put_to.color = to_get.color; put_to.manaCost = to_get.manaCost; put_to.inPlay = to_get.inPlay; put_to.tapped = to_get.tapped; put_to.class = to_get.class; put_to.id = to_get.id; put_to.enchanted = to_get.enchanted; put_to.artifact = to_get.artifact; put_to.class = to_get.class; put.to.abilities = new char[strlen(to_get.abilities) +1]; strcpy(put_to.abilities, to_get.abilities); put.to.keywords = new char[strlen(to_get.keywords) +1]; strcpy(put_to.keywords, to_get.keywords); put.to.flavorText = new char[strlen(to_get.flavorText) +1]; strcpy(put_to.flavorText, to_get.flavorText); if (to_get.class = "Spell"){ put_to.baseToughness = to_get.baseToughness; put_to.basePower = to_get.basePower; put_to.currToughness = to_get.currToughness; put_to.currPower = to_get.currPower; } } // ---------- player.h #ifndef player.h #define player.h #include "list.h" // ============ class CardList() : public LinkedList(){ public: CardList(); ~CardList(); protected: virtual void findCard(Card&); virtual void addCard(Card* ); virtual void removeCard(Node* root, int id); virtual void deleteAll(); virtual void displayAll(); virtual void copyCard(const Conception*, Node*&); Node* root; } // --------- class Library() : public CardList(){ public: Library(); ~Library(); protected: Card* card; int numCards; findCard(Card&); // get Card and fill empty template } // ----------- class Deck() : public CardList(){ public: Deck(); ~Deck(); protected: enum deckColor { WHITE, BLUE, BLACK, RED, GREEN, MIXED }; char* deckName; } // =============== class Mana(int amount) : public Conception { public: Mana() : displayTotal(0), classType(0) { displayTotal = 0; classType = new char[strlen("Mana") + 1]; classType = "Mana"; }; protected: int accrued; void add(); void remove(); int displayTotal(); } inline Mana::add(){ accrued += 1; } inline Mana::remove(){ accrued -= 1; } inline Mana::displayTotal(){ return accrued; } // ================ class Stats() : public Conception { public: friend class Player; friend class Game; Stats() : wins(0), losses(0), winRatio(0) { wins = 0; losses = 0; if ( (wins + losses != 0) winRatio = wins / (wins + losses); else winRatio = 0; classType = new char[strlen("Stats") + 1]; classType = "Stats"; } protected: int wins; int losses; float winRatio; void int getStats(Stats*& ); } // ================== class Player() : public Conception{ public: Player() : wins(0), losses(0), winRatio(0) { fname = NULL; lname = NULL; stats = NULL; CardList = NULL; classType = new char[strlen("Player") + 1]; classType = "Player"; }; ~Player(); Player(const Player & obj); protected: // member variables char* fname; char* lname; Stats stats; // holds previous game statistics CardList* deck[]; // hold multiple decks that player might use - put ll in this private: // member functions void changeName(const char[], const char[]); void shuffleDeck(int); void seeStats(Stats*& ); void displayDeck(int); chooseDeck(); } // -------------------- class Wizard(Card) : public Player(){ public: Wizard() : { mana = NULL; rootL = NULL; rootH = NULL}; ~Wizard(); protected: playCard(const Card &); removeCard(Card &); attackWithCard(Card &); enchantWithCard(Card &); disenchantWithCard(Card &); healWithCard(Card &); equipWithCard(Card &); Mana* mana[]; Library* rootL; // Library Library* rootH; // Hand } #endif

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Linked List manipulation, issues retrieving data c++

- by floatfil

I'm trying to implement some functions to manipulate a linked list. The implementation is a template typename T and the class is 'List' which includes a 'head' pointer and also a struct: struct Node { // the node in a linked list T* data; // pointer to actual data, operations in T Node* next; // pointer to a Node }; Since it is a template, and 'T' can be any data, how do I go about checking the data of a list to see if it matches the data input into the function? The function is called 'retrieve' and takes two parameters, the data and a pointer: bool retrieve(T target, T*& ptr); // This is the prototype we need to use for the project "bool retrieve : similar to remove, but not removed from list. If there are duplicates in the list, the first one encountered is retrieved. Second parameter is unreliable if return value is false. E.g., " Employee target("duck", "donald"); success = company1.retrieve(target, oneEmployee); if (success) { cout << "Found in list: " << *oneEmployee << endl; } And the function is called like this: company4.retrieve(emp3, oneEmployee) So that when you cout *oneEmployee, you'll get the data of that pointer (in this case the data is of type Employee). (Also, this is assuming all data types have the apropriate overloaded operators) I hope this makes sense so far, but my issue is in comparing the data in the parameter and the data while going through the list. (The data types that we use all include overloads for equality operators, so oneData == twoData is valid) This is what I have so far: template <typename T> bool List<T>::retrieve(T target , T*& ptr) { List<T>::Node* dummyPtr = head; // point dummy pointer to what the list's head points to for(;;) { if (*dummyPtr->data == target) { // EDIT: it now compiles, but it breaks here and I get an Access Violation error. ptr = dummyPtr->data; // set the parameter pointer to the dummy pointer return true; // return true } else { dummyPtr = dummyPtr->next; // else, move to the next data node } } return false; } Here is the implementation for the Employee class: //-------------------------- constructor ----------------------------------- Employee::Employee(string last, string first, int id, int sal) { idNumber = (id >= 0 && id <= MAXID? id : -1); salary = (sal >= 0 ? sal : -1); lastName = last; firstName = first; } //-------------------------- destructor ------------------------------------ // Needed so that memory for strings is properly deallocated Employee::~Employee() { } //---------------------- copy constructor ----------------------------------- Employee::Employee(const Employee& E) { lastName = E.lastName; firstName = E.firstName; idNumber = E.idNumber; salary = E.salary; } //-------------------------- operator= --------------------------------------- Employee& Employee::operator=(const Employee& E) { if (&E != this) { idNumber = E.idNumber; salary = E.salary; lastName = E.lastName; firstName = E.firstName; } return *this; } //----------------------------- setData ------------------------------------ // set data from file bool Employee::setData(ifstream& inFile) { inFile >> lastName >> firstName >> idNumber >> salary; return idNumber >= 0 && idNumber <= MAXID && salary >= 0; } //------------------------------- < ---------------------------------------- // < defined by value of name bool Employee::operator<(const Employee& E) const { return lastName < E.lastName || (lastName == E.lastName && firstName < E.firstName); } //------------------------------- <= ---------------------------------------- // < defined by value of inamedNumber bool Employee::operator<=(const Employee& E) const { return *this < E || *this == E; } //------------------------------- > ---------------------------------------- // > defined by value of name bool Employee::operator>(const Employee& E) const { return lastName > E.lastName || (lastName == E.lastName && firstName > E.firstName); } //------------------------------- >= ---------------------------------------- // < defined by value of name bool Employee::operator>=(const Employee& E) const { return *this > E || *this == E; } //----------------- operator == (equality) ---------------- // if name of calling and passed object are equal, // return true, otherwise false // bool Employee::operator==(const Employee& E) const { return lastName == E.lastName && firstName == E.firstName; } //----------------- operator != (inequality) ---------------- // return opposite value of operator== bool Employee::operator!=(const Employee& E) const { return !(*this == E); } //------------------------------- << --------------------------------------- // display Employee object ostream& operator<<(ostream& output, const Employee& E) { output << setw(4) << E.idNumber << setw(7) << E.salary << " " << E.lastName << " " << E.firstName << endl; return output; } I will include a check for NULL pointer but I just want to get this working and will test it on a list that includes the data I am checking. Thanks to whoever can help and as usual, this is for a course so I don't expect or want the answer, but any tips as to what might be going wrong will help immensely!

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Specializing function template for both std::string and char*

- by sad_man

As the title says I want to specialize a function template for both string and char pointer, so far I did this but I can not figure out passing the string parameters by reference. #include <iostream> #include <string> template<typename T> void xxx(T param) { std::cout << "General : "<< sizeof(T) << std::endl; } template<> void xxx<char*>(char* param) { std::cout << "Char ptr: "<< strlen(param) << std::endl; } template<> void xxx<const char* >(const char* param) { std::cout << "Const Char ptr : "<< strlen(param)<< std::endl; } template<> void xxx<const std::string & >(const std::string & param) { std::cout << "Const String : "<< param.size()<< std::endl; } template<> void xxx<std::string >(std::string param) { std::cout << "String : "<< param.size()<< std::endl; } int main() { xxx("word"); std::string aword("word"); xxx(aword); std::string const cword("const word"); xxx(cword); } Also template<> void xxx<const std::string & >(const std::string & param) thing just does not working. If I rearranged the opriginal template to accept parameters as T& then the char * is required to be char * & which is not good for static text in code. Please help !

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java.lang.IllegalAccessException during Ant jwsc webservice build

- by KevB

Hi. I have a large application, part of which relies on a set of 3 webservices. I'm currently in the process of writing an Ant build script to build and package the application into an EAR file. When building the web sub-project for this application I use the <jwsc> task in Ant to compile the webservices. This causes an IllegalAccessException, as outlined in the stack trace below: [jwsc] warning: 'includeantruntime' was not set, defaulting to build.sysclasspath=last; set to false for repeatable builds [jwsc] JWS: processing module weboutput [jwsc] Parsing source files [jwsc] Parsing source files [jwsc] 3 JWS files being processed for module weboutput [jwsc] JWS: C:\dev\ir\irWeb\src\webservices\DailyRun.java Validated. [jwsc] JWS: C:\dev\ir\irWeb\src\webservices\PendingRegistrationsSweep.java Validated. [jwsc] JWS: C:\dev\ir\irWeb\src\webservices\RegistrationsGoLive.java Validated. [jwsc] Compiling 6 source files to C:\DOCUME~1\KEVIN~1.BRE\LOCALS~1\Temp\_5l950r [jwsc] An exception has occurred in the compiler (1.6.0_23). Please file a bug at the Java Developer Connection (http://java.sun.com/webapps/bugreport) after checking the Bug Parade for duplicates. Include your program and the following diagnostic in your report. Thank you. [jwsc] java.lang.IllegalAccessError: tried to access class com.sun.tools.javac.jvm.ClassReader$AnnotationDefaultCompleter from class com.sun.tools.javac.jvm.ClassReader [jwsc] at com.sun.tools.javac.jvm.ClassReader.attachAnnotationDefault(ClassReader.java:1128) [jwsc] at com.sun.tools.javac.jvm.ClassReader.readMemberAttr(ClassReader.java:906) [jwsc] at com.sun.tools.javac.jvm.ClassReader.readMemberAttrs(ClassReader.java:1027) [jwsc] at com.sun.tools.javac.jvm.ClassReader.readMethod(ClassReader.java:1490) [jwsc] at com.sun.tools.javac.jvm.ClassReader.readClass(ClassReader.java:1586) [jwsc] at com.sun.tools.javac.jvm.ClassReader.readClassFile(ClassReader.java:1658) [jwsc] at com.sun.tools.javac.jvm.ClassReader.fillIn(ClassReader.java:1845) [jwsc] at com.sun.tools.javac.jvm.ClassReader.complete(ClassReader.java:1777) [jwsc] at com.sun.tools.javac.code.Symbol.complete(Symbol.java:386) [jwsc] at com.sun.tools.javac.code.Symbol$ClassSymbol.complete(Symbol.java:763) [jwsc] at com.sun.tools.javac.jvm.ClassReader.loadClass(ClassReader.java:1951) [jwsc] at com.sun.tools.javac.comp.Resolve.loadClass(Resolve.java:842) [jwsc] at com.sun.tools.javac.comp.Resolve.findIdentInPackage(Resolve.java:1011) [jwsc] at com.sun.tools.javac.comp.Attr.selectSym(Attr.java:1921) [jwsc] at com.sun.tools.javac.comp.Attr.visitSelect(Attr.java:1835) [jwsc] at com.sun.tools.javac.tree.JCTree$JCFieldAccess.accept(JCTree.java:1522) [jwsc] at com.sun.tools.javac.comp.Attr.attribTree(Attr.java:360) [jwsc] at com.sun.tools.javac.comp.Attr.attribType(Attr.java:390) [jwsc] at com.sun.tools.javac.comp.MemberEnter.attribImportType(MemberEnter.java:681) [jwsc] at com.sun.tools.javac.comp.MemberEnter.visitImport(MemberEnter.java:545) [jwsc] at com.sun.tools.javac.tree.JCTree$JCImport.accept(JCTree.java:495) [jwsc] at com.sun.tools.javac.comp.MemberEnter.memberEnter(MemberEnter.java:387) [jwsc] at com.sun.tools.javac.comp.MemberEnter.memberEnter(MemberEnter.java:399) [jwsc] at com.sun.tools.javac.comp.MemberEnter.visitTopLevel(MemberEnter.java:512) [jwsc] at com.sun.tools.javac.tree.JCTree$JCCompilationUnit.accept(JCTree.java:446) [jwsc] at com.sun.tools.javac.comp.MemberEnter.memberEnter(MemberEnter.java:387) [jwsc] at com.sun.tools.javac.comp.MemberEnter.complete(MemberEnter.java:819) [jwsc] at com.sun.tools.javac.code.Symbol.complete(Symbol.java:386) [jwsc] at com.sun.tools.javac.code.Symbol$ClassSymbol.complete(Symbol.java:763) [jwsc] at com.sun.tools.javac.comp.Enter.complete(Enter.java:464) [jwsc] at com.sun.tools.javac.comp.Enter.main(Enter.java:442) [jwsc] at com.sun.tools.javac.main.JavaCompiler.enterTrees(JavaCompiler.java:819) [jwsc] at com.sun.tools.javac.main.JavaCompiler.compile(JavaCompiler.java:727) [jwsc] at com.sun.tools.javac.main.Main.compile(Main.java:353) [jwsc] at com.sun.tools.javac.main.Main.compile(Main.java:279) [jwsc] at com.sun.tools.javac.main.Main.compile(Main.java:270) [jwsc] at com.sun.tools.javac.Main.compile(Main.java:69) [jwsc] at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) [jwsc] at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) [jwsc] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) [jwsc] at java.lang.reflect.Method.invoke(Method.java:597) [jwsc] at org.apache.tools.ant.taskdefs.compilers.Javac13.execute(Javac13.java:56) [jwsc] at org.apache.tools.ant.taskdefs.Javac.compile(Javac.java:1097) [jwsc] at weblogic.wsee.tools.anttasks.DelegatingJavacTask$ExposingJavac.compile(DelegatingJavacTask.java:343) [jwsc] at weblogic.wsee.tools.anttasks.DelegatingJavacTask.compile(DelegatingJavacTask.java:286) [jwsc] at weblogic.wsee.tools.anttasks.JwscTask.javac(JwscTask.java:335) [jwsc] at weblogic.wsee.tools.anttasks.JwsModule.compile(JwsModule.java:390) [jwsc] at weblogic.wsee.tools.anttasks.JwsModule.build(JwsModule.java:262) [jwsc] at weblogic.wsee.tools.anttasks.JwscTask.execute(JwscTask.java:227) [jwsc] at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:291) [jwsc] at sun.reflect.GeneratedMethodAccessor4.invoke(Unknown Source) [jwsc] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) [jwsc] at java.lang.reflect.Method.invoke(Method.java:597) [jwsc] at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.java:106) [jwsc] at org.apache.tools.ant.Task.perform(Task.java:348) [jwsc] at org.apache.tools.ant.Target.execute(Target.java:390) [jwsc] at org.apache.tools.ant.Target.performTasks(Target.java:411) [jwsc] at org.apache.tools.ant.Project.executeSortedTargets(Project.java:1397) [jwsc] at org.apache.tools.ant.helper.SingleCheckExecutor.executeTargets(SingleCheckExecutor.java:38) [jwsc] at org.apache.tools.ant.Project.executeTargets(Project.java:1249) [jwsc] at org.apache.tools.ant.taskdefs.Ant.execute(Ant.java:442) [jwsc] at org.apache.tools.ant.taskdefs.CallTarget.execute(CallTarget.java:105) [jwsc] at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:291) [jwsc] at sun.reflect.GeneratedMethodAccessor4.invoke(Unknown Source) [jwsc] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) [jwsc] at java.lang.reflect.Method.invoke(Method.java:597) [jwsc] at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.java:106) [jwsc] at org.apache.tools.ant.Task.perform(Task.java:348) [jwsc] at org.apache.tools.ant.Target.execute(Target.java:390) [jwsc] at org.apache.tools.ant.Target.performTasks(Target.java:411) [jwsc] at org.apache.tools.ant.Project.executeSortedTargets(Project.java:1397) [jwsc] at org.apache.tools.ant.Project.executeTarget(Project.java:1366) [jwsc] at com.bea.workshop.cmdline.antlib.AntExTask.execute(AntExTask.java:406) [jwsc] at com.bea.workshop.cmdline.antlib.AntCallExTask.execute(AntCallExTask.java:118) [jwsc] at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:291) [jwsc] at sun.reflect.GeneratedMethodAccessor4.invoke(Unknown Source) [jwsc] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) [jwsc] at java.lang.reflect.Method.invoke(Method.java:597) [jwsc] at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.java:106) [jwsc] at org.apache.tools.ant.Task.perform(Task.java:348) [jwsc] at org.apache.tools.ant.Target.execute(Target.java:390) [jwsc] at org.apache.tools.ant.Target.performTasks(Target.java:411) [jwsc] at org.apache.tools.ant.Project.executeSortedTargets(Project.java:1397) [jwsc] at org.apache.tools.ant.Project.executeTarget(Project.java:1366) [jwsc] at com.bea.workshop.cmdline.antlib.AntExTask.execute(AntExTask.java:406) [jwsc] at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:291) [jwsc] at sun.reflect.GeneratedMethodAccessor4.invoke(Unknown Source) [jwsc] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) [jwsc] at java.lang.reflect.Method.invoke(Method.java:597) [jwsc] at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.java:106) [jwsc] at org.apache.tools.ant.Task.perform(Task.java:348) [jwsc] at org.apache.tools.ant.taskdefs.Sequential.execute(Sequential.java:68) [jwsc] at net.sf.antcontrib.logic.IfTask.execute(IfTask.java:217) [jwsc] at sun.reflect.GeneratedMethodAccessor44.invoke(Unknown Source) [jwsc] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) [jwsc] at java.lang.reflect.Method.invoke(Method.java:597) [jwsc] at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.java:106) [jwsc] at org.apache.tools.ant.TaskAdapter.execute(TaskAdapter.java:154) [jwsc] at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:291) [jwsc] at sun.reflect.GeneratedMethodAccessor4.invoke(Unknown Source) [jwsc] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) [jwsc] at java.lang.reflect.Method.invoke(Method.java:597) [jwsc] at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.java:106) [jwsc] at org.apache.tools.ant.Task.perform(Task.java:348) [jwsc] at org.apache.tools.ant.taskdefs.Sequential.execute(Sequential.java:68) [jwsc] at net.sf.antcontrib.logic.IfTask.execute(IfTask.java:197) [jwsc] at sun.reflect.GeneratedMethodAccessor44.invoke(Unknown Source) [jwsc] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) [jwsc] at java.lang.reflect.Method.invoke(Method.java:597) [jwsc] at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.java:106) [jwsc] at org.apache.tools.ant.TaskAdapter.execute(TaskAdapter.java:154) [jwsc] at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:291) [jwsc] at sun.reflect.GeneratedMethodAccessor4.invoke(Unknown Source) [jwsc] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) [jwsc] at java.lang.reflect.Method.invoke(Method.java:597) [jwsc] at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.java:106) [jwsc] at org.apache.tools.ant.Task.perform(Task.java:348) [jwsc] at org.apache.tools.ant.taskdefs.Sequential.execute(Sequential.java:68) [jwsc] at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:291) [jwsc] at sun.reflect.GeneratedMethodAccessor4.invoke(Unknown Source) [jwsc] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) [jwsc] at java.lang.reflect.Method.invoke(Method.java:597) [jwsc] at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.java:106) [jwsc] at org.apache.tools.ant.Task.perform(Task.java:348) [jwsc] at org.apache.tools.ant.taskdefs.MacroInstance.execute(MacroInstance.java:398) [jwsc] at net.sf.antcontrib.logic.ForTask.doSequentialIteration(ForTask.java:259) [jwsc] at net.sf.antcontrib.logic.ForTask.doToken(ForTask.java:268) [jwsc] at net.sf.antcontrib.logic.ForTask.doTheTasks(ForTask.java:299) [jwsc] at net.sf.antcontrib.logic.ForTask.execute(ForTask.java:244) [jwsc] at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:291) [jwsc] at sun.reflect.GeneratedMethodAccessor4.invoke(Unknown Source) [jwsc] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) [jwsc] at java.lang.reflect.Method.invoke(Method.java:597) [jwsc] at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.java:106) [jwsc] at org.apache.tools.ant.Task.perform(Task.java:348) [jwsc] at org.apache.tools.ant.taskdefs.Sequential.execute(Sequential.java:68) [jwsc] at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:291) [jwsc] at sun.reflect.GeneratedMethodAccessor4.invoke(Unknown Source) [jwsc] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) [jwsc] at java.lang.reflect.Method.invoke(Method.java:597) [jwsc] at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.java:106) [jwsc] at org.apache.tools.ant.Task.perform(Task.java:348) [jwsc] at org.apache.tools.ant.taskdefs.MacroInstance.execute(MacroInstance.java:398) [jwsc] at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:291) [jwsc] at sun.reflect.GeneratedMethodAccessor4.invoke(Unknown Source) [jwsc] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) [jwsc] at java.lang.reflect.Method.invoke(Method.java:597) [jwsc] at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.java:106) [jwsc] at org.apache.tools.ant.Task.perform(Task.java:348) [jwsc] at org.apache.tools.ant.Target.execute(Target.java:390) [jwsc] at org.apache.tools.ant.Target.performTasks(Target.java:411) [jwsc] at org.apache.tools.ant.Project.executeSortedTargets(Project.java:1397) [jwsc] at org.apache.tools.ant.helper.SingleCheckExecutor.executeTargets(SingleCheckExecutor.java:38) [jwsc] at org.apache.tools.ant.Project.executeTargets(Project.java:1249) [jwsc] at org.apache.tools.ant.taskdefs.Ant.execute(Ant.java:442) [jwsc] at org.apache.tools.ant.taskdefs.CallTarget.execute(CallTarget.java:105) [jwsc] at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:291) [jwsc] at sun.reflect.GeneratedMethodAccessor4.invoke(Unknown Source) [jwsc] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) [jwsc] at java.lang.reflect.Method.invoke(Method.java:597) [jwsc] at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.java:106) [jwsc] at org.apache.tools.ant.Task.perform(Task.java:348) [jwsc] at org.apache.tools.ant.Target.execute(Target.java:390) [jwsc] at org.apache.tools.ant.Target.performTasks(Target.java:411) [jwsc] at org.apache.tools.ant.Project.executeSortedTargets(Project.java:1397) [jwsc] at org.apache.tools.ant.Project.executeTarget(Project.java:1366) [jwsc] at org.apache.tools.ant.helper.DefaultExecutor.executeTargets(DefaultExecutor.java:41) [jwsc] at org.apache.tools.ant.Project.executeTargets(Project.java:1249) [jwsc] at org.apache.tools.ant.Main.runBuild(Main.java:801) [jwsc] at org.apache.tools.ant.Main.startAnt(Main.java:218) [jwsc] at org.apache.tools.ant.launch.Launcher.run(Launcher.java:280) [jwsc] at org.apache.tools.ant.launch.Launcher.main(Launcher.java:109) [AntUtil.deleteDir] Deleting directory C:\DOCUME~1\KEVIN~1.BRE\LOCALS~1\Temp_5l950r The Ant target that uses the <jwsc> task is this: <target name="webservice.build" depends="init,generated.root.init"> <path id="jwsc.srcpath"> <path path="${java.sourcepath}" /> <pathelement path="build/assembly/.src" /> </path> <taskdef name="jwsc" classname="weblogic.wsee.tools.anttasks.JwscTask" > <classpath> <path refid="weblogic.jar.classpath" /> </classpath> </taskdef> <property name="jwsc.module.root" value="${project.dir}/build/weboutput"/> <property name="jwsc.contextpath" value="irWeb"/> <property name="jwsc.srcpath.prop" refid="jwsc.srcpath"/> <path id="jwsc.classpath"> <path refid="weblogic.jar.classpath" /> <path refid="java.classpath" /> <pathelement path="${java.outpath}" /> </path> <jwsc destdir="${project.dir}/build" classpathref="jwsc.classpath"> <module name="weboutput" explode="true" contextPath="${jwsc.contextpath}" > <jwsFileSet srcdir="${webservices.dir}" type="JAXRPC"> <include name="**/*.java"/> </jwsFileSet> <descriptor file="${jwsc.module.root}/WEB-INF/web.xml" /> <descriptor file="${jwsc.module.root}/WEB-INF/weblogic.xml" /> </module> </jwsc> </target> I have no idea what could be causing the compiler to throw this error at build time, and a day of google searching has turned up other instances of this error caused by different triggers, and solutions for those propblems didn't work for me. I also found a single report on the Oracle forums that seemed to be a carbon copy of this issue, but there were no replies. The application is written in Weblogic Workshop 10, runs on Weblogic Server 10.3, and uses Beehive / NetUI. Not sure if that would make a difference or not though. The build scripts were automatically generated by Weblogic Workshop, with some tweaks and fixes made to other aspects of the files by myself to fix other compatability issues. I am using Java 1.6.0_23 from Sun, and Ant 1.8.1 Any help or advice would be greatly appreciated.

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Problem in creation MDB Queue connection at Jboss StartUp

- by Amit Ruwali

I am not able to create a Queue connection in JBOSS4.2.3GA Version & Java1.5, as I am using MDB as per the below details. I am putting this MDB in a jar file(named utsJar.jar) and copied it in deploy folder of JBOSS, In the test env. this MDB works well but in another env. [ env settings and jboss/java ver is same ] it is throwing error at jboss start up [attached below ]. I have searched for this error but couldn't find any solution till now; was there any issue of port confict or something related with configurations ? UTSMessageListner.java @MessageDriven(activationConfig = { @ActivationConfigProperty(propertyName="destinationType", propertyValue="javax.jms.Queue"), @ActivationConfigProperty(propertyName="destination", propertyValue="queue/UTSQueue") }) @TransactionAttribute(TransactionAttributeType.NOT_SUPPORTED) public class UTSMessageListner implements MessageListener { public void onMessage(Message msg) { ObjectMessage objmsg = (ObjectMessage) msg; try { UTSListVO utsMessageListVO = (UTSListVO) objmsg.getObject(); if(utsMessageListVO.getUtsMessageList()!=null) { UtsWebServiceLogger.logMessage("UTSMessageListner:onMessage: SIZE Of UTSMessage List =[" +utsMessageListVO.getUtsMessageList().size() + "]"); UTSDataLayerImpl.getInstance().insertUTSMessage(utsMessageListVO); } else { UtsWebServiceLogger.logMessage("UTSMessageListner:onMessage: Message List is NULL"); } } catch (Exception ex) { UtsWebServiceLogger.logMessage("UTSMessageListner:onMessage: Error Receiving Message"+ExceptionUtility.getStackTrace(ex)); } } } [ I have also attached whole server.log as an attach] /// ///////////////////////////////// Error Trace is Below while starting the server /////////////////////////// 2010-03-12 07:05:40,061 WARN [org.jboss.ejb3.mdb.MessagingContainer] Could not find the queue destination-jndi-name=queue/UTSQueue 2010-03-12 07:05:40,061 WARN [org.jboss.ejb3.mdb.MessagingContainer] destination not found: queue/UTSQueue reason: javax.naming.NameNotFoundException: queue not bound 2010-03-12 07:05:40,061 WARN [org.jboss.ejb3.mdb.MessagingContainer] creating a new temporary destination: queue/UTSQueue 2010-03-12 07:05:40,071 WARN [org.jboss.system.ServiceController] Problem starting service jboss.j2ee:ear=uts.ear,jar=utsJar.jar,name=UTSMessageListner,service=EJB3 java.lang.NullPointerException at org.jboss.mq.server.jmx.DestinationManager.createDestination(DestinationManager.java:336) at org.jboss.mq.server.jmx.DestinationManager.createQueue(DestinationManager.java:293) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:585) at org.jboss.mx.interceptor.ReflectedDispatcher.invoke(ReflectedDispatcher.java:155) at org.jboss.mx.server.Invocation.dispatch(Invocation.java:94) at org.jboss.mx.server.Invocation.invoke(Invocation.java:86) at org.jboss.mx.server.AbstractMBeanInvoker.invoke(AbstractMBeanInvoker.java:264) at org.jboss.mx.server.MBeanServerImpl.invoke(MBeanServerImpl.java:659) at org.jboss.ejb3.JmxClientKernelAbstraction.invoke(JmxClientKernelAbstraction.java:44) at org.jboss.ejb3.jms.DestinationManagerJMSDestinationFactory.createDestination(DestinationManagerJMSDestinationFactory.java:75) at org.jboss.ejb3.mdb.MessagingContainer.createTemporaryDestination(MessagingContainer.java:573) at org.jboss.ejb3.mdb.MessagingContainer.createDestination(MessagingContainer.java:512) at org.jboss.ejb3.mdb.MessagingContainer.innerCreateQueue(MessagingContainer.java:438) at org.jboss.ejb3.mdb.MessagingContainer.jmsCreate(MessagingContainer.java:400) at org.jboss.ejb3.mdb.MessagingContainer.innerStart(MessagingContainer.java:166) at org.jboss.ejb3.mdb.MessagingContainer.start(MessagingContainer.java:152) at org.jboss.ejb3.mdb.MDB.start(MDB.java:126) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:585) at org.jboss.ejb3.ServiceDelegateWrapper.startService(ServiceDelegateWrapper.java:103) at org.jboss.system.ServiceMBeanSupport.jbossInternalStart(ServiceMBeanSupport.java:289) at org.jboss.system.ServiceMBeanSupport.jbossInternalLifecycle(ServiceMBeanSupport.java:245) at sun.reflect.GeneratedMethodAccessor4.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:585) at org.jboss.mx.interceptor.ReflectedDispatcher.invoke(ReflectedDispatcher.java:155) at org.jboss.mx.server.Invocation.dispatch(Invocation.java:94) at org.jboss.mx.server.Invocation.invoke(Invocation.java:86) at org.jboss.mx.server.AbstractMBeanInvoker.invoke(AbstractMBeanInvoker.java:264) at org.jboss.mx.server.MBeanServerImpl.invoke(MBeanServerImpl.java:659) at org.jboss.system.ServiceController$ServiceProxy.invoke(ServiceController.java:978) at $Proxy0.start(Unknown Source) at org.jboss.system.ServiceController.start(ServiceController.java:417) at sun.reflect.GeneratedMethodAccessor10.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:585) at org.jboss.mx.interceptor.ReflectedDispatcher.invoke(ReflectedDispatcher.java:155) at org.jboss.mx.server.Invocation.dispatch(Invocation.java:94) at org.jboss.mx.server.Invocation.invoke(Invocation.java:86) at org.jboss.mx.server.AbstractMBeanInvoker.invoke(AbstractMBeanInvoker.java:264) at org.jboss.mx.server.MBeanServerImpl.invoke(MBeanServerImpl.java:659) at org.jboss.mx.util.MBeanProxyExt.invoke(MBeanProxyExt.java:210) at $Proxy53.start(Unknown Source) at org.jboss.ejb3.JmxKernelAbstraction.install(JmxKernelAbstraction.java:120) at org.jboss.ejb3.Ejb3Deployment.registerEJBContainer(Ejb3Deployment.java:301) at org.jboss.ejb3.Ejb3Deployment.start(Ejb3Deployment.java:362) at org.jboss.ejb3.Ejb3Module.startService(Ejb3Module.java:91) at org.jboss.system.ServiceMBeanSupport.jbossInternalStart(ServiceMBeanSupport.java:289) at org.jboss.system.ServiceMBeanSupport.jbossInternalLifecycle(ServiceMBeanSupport.java:245) at sun.reflect.GeneratedMethodAccessor4.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:585) at org.jboss.mx.interceptor.ReflectedDispatcher.invoke(ReflectedDispatcher.java:155) at org.jboss.mx.server.Invocation.dispatch(Invocation.java:94) at org.jboss.mx.server.Invocation.invoke(Invocation.java:86) at org.jboss.mx.server.AbstractMBeanInvoker.invoke(AbstractMBeanInvoker.java:264) at org.jboss.mx.server.MBeanServerImpl.invoke(MBeanServerImpl.java:659) at org.jboss.system.ServiceController$ServiceProxy.invoke(ServiceController.java:978) at $Proxy0.start(Unknown Source) at org.jboss.system.ServiceController.start(ServiceController.java:417) at sun.reflect.GeneratedMethodAccessor10.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:585) at org.jboss.mx.interceptor.ReflectedDispatcher.invoke(ReflectedDispatcher.java:155) at org.jboss.mx.server.Invocation.dispatch(Invocation.java:94) at org.jboss.mx.server.Invocation.invoke(Invocation.java:86) at org.jboss.mx.server.AbstractMBeanInvoker.invoke(AbstractMBeanInvoker.java:264) at org.jboss.mx.server.MBeanServerImpl.invoke(MBeanServerImpl.java:659) at org.jboss.mx.util.MBeanProxyExt.invoke(MBeanProxyExt.java:210) at $Proxy33.start(Unknown Source) at org.jboss.ejb3.EJB3Deployer.start(EJB3Deployer.java:512) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:585) at org.jboss.mx.interceptor.ReflectedDispatcher.invoke(ReflectedDispatcher.java:155) at org.jboss.mx.server.Invocation.dispatch(Invocation.java:94) at org.jboss.mx.interceptor.AbstractInterceptor.invoke(AbstractInterceptor.java:133) at org.jboss.mx.server.Invocation.invoke(Invocation.java:88) at org.jboss.mx.interceptor.ModelMBeanOperationInterceptor.invoke(ModelMBeanOperationInterceptor.java:142) at org.jboss.mx.interceptor.DynamicInterceptor.invoke(DynamicInterceptor.java:97) at org.jboss.system.InterceptorServiceMBeanSupport.invokeNext(InterceptorServiceMBeanSupport.java:238) at org.jboss.wsf.container.jboss42.DeployerInterceptor.start(DeployerInterceptor.java:87) at org.jboss.deployment.SubDeployerInterceptorSupport$XMBeanInterceptor.start(SubDeployerInterceptorSupport.java:188) at org.jboss.deployment.SubDeployerInterceptor.invoke(SubDeployerInterceptor.java:95) at org.jboss.mx.server.Invocation.invoke(Invocation.java:88) at org.jboss.mx.server.AbstractMBeanInvoker.invoke(AbstractMBeanInvoker.java:264) at org.jboss.mx.server.MBeanServerImpl.invoke(MBeanServerImpl.java:659) at org.jboss.mx.util.MBeanProxyExt.invoke(MBeanProxyExt.java:210) at $Proxy34.start(Unknown Source) at org.jboss.deployment.MainDeployer.start(MainDeployer.java:1025) at org.jboss.deployment.MainDeployer.start(MainDeployer.java:1015) at org.jboss.deployment.MainDeployer.deploy(MainDeployer.java:819) at org.jboss.deployment.MainDeployer.deploy(MainDeployer.java:782) at sun.reflect.GeneratedMethodAccessor20.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:585) at org.jboss.mx.interceptor.ReflectedDispatcher.invoke(ReflectedDispatcher.java:155) at org.jboss.mx.server.Invocation.dispatch(Invocation.java:94) at org.jboss.mx.interceptor.AbstractInterceptor.invoke(AbstractInterceptor.java:133) at org.jboss.mx.server.Invocation.invoke(Invocation.java:88) at org.jboss.mx.interceptor.ModelMBeanOperationInterceptor.invoke(ModelMBeanOperationInterceptor.java:142) at org.jboss.mx.server.Invocation.invoke(Invocation.java:88) at org.jboss.mx.server.AbstractMBeanInvoker.invoke(AbstractMBeanInvoker.java:264) at org.jboss.mx.server.MBeanServerImpl.invoke(MBeanServerImpl.java:659) at org.jboss.mx.util.MBeanProxyExt.invoke(MBeanProxyExt.java:210) at $Proxy9.deploy(Unknown Source) at org.jboss.deployment.scanner.URLDeploymentScanner.deploy(URLDeploymentScanner.java:421) at org.jboss.deployment.scanner.URLDeploymentScanner.scan(URLDeploymentScanner.java:634) at org.jboss.deployment.scanner.AbstractDeploymentScanner$ScannerThread.doScan(AbstractDeploymentScanner.java:263) at org.jboss.deployment.scanner.AbstractDeploymentScanner.startService(AbstractDeploymentScanner.java:336) at org.jboss.system.ServiceMBeanSupport.jbossInternalStart(ServiceMBeanSupport.java:289) at org.jboss.system.ServiceMBeanSupport.jbossInternalLifecycle(ServiceMBeanSupport.java:245) at sun.reflect.GeneratedMethodAccessor4.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:585) at org.jboss.mx.interceptor.ReflectedDispatcher.invoke(ReflectedDispatcher.java:155) at org.jboss.mx.server.Invocation.dispatch(Invocation.java:94) at org.jboss.mx.server.Invocation.invoke(Invocation.java:86) at org.jboss.mx.server.AbstractMBeanInvoker.invoke(AbstractMBeanInvoker.java:264) at org.jboss.mx.server.MBeanServerImpl.invoke(MBeanServerImpl.java:659) at org.jboss.system.ServiceController$ServiceProxy.invoke(ServiceController.java:978) at $Proxy0.start(Unknown Source) at org.jboss.system.ServiceController.start(ServiceController.java:417) at sun.reflect.GeneratedMethodAccessor10.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:585) at org.jboss.mx.interceptor.ReflectedDispatcher.invoke(ReflectedDispatcher.java:155) at org.jboss.mx.server.Invocation.dispatch(Invocation.java:94) at org.jboss.mx.server.Invocation.invoke(Invocation.java:86) at org.jboss.mx.server.AbstractMBeanInvoker.invoke(AbstractMBeanInvoker.java:264) at org.jboss.mx.server.MBeanServerImpl.invoke(MBeanServerImpl.java:659) at org.jboss.mx.util.MBeanProxyExt.invoke(MBeanProxyExt.java:210) at $Proxy4.start(Unknown Source) at org.jboss.deployment.SARDeployer.start(SARDeployer.java:304) at org.jboss.deployment.MainDeployer.start(MainDeployer.java:1025) at org.jboss.deployment.MainDeployer.deploy(MainDeployer.java:819) at org.jboss.deployment.MainDeployer.deploy(MainDeployer.java:782) at org.jboss.deployment.MainDeployer.deploy(MainDeployer.java:766) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:585) at org.jboss.mx.interceptor.ReflectedDispatcher.invoke(ReflectedDispatcher.java:155) at org.jboss.mx.server.Invocation.dispatch(Invocation.java:94) at org.jboss.mx.interceptor.AbstractInterceptor.invoke(AbstractInterceptor.java:133) at org.jboss.mx.server.Invocation.invoke(Invocation.java:88) at org.jboss.mx.interceptor.ModelMBeanOperationInterceptor.invoke(ModelMBeanOperationInterceptor.java:142) at org.jboss.mx.server.Invocation.invoke(Invocation.java:88) at org.jboss.mx.server.AbstractMBeanInvoker.invoke(AbstractMBeanInvoker.java:264) at org.jboss.mx.server.MBeanServerImpl.invoke(MBeanServerImpl.java:659) at org.jboss.mx.util.MBeanProxyExt.invoke(MBeanProxyExt.java:210) at $Proxy5.deploy(Unknown Source) at org.jboss.system.server.ServerImpl.doStart(ServerImpl.java:482) at org.jboss.system.server.ServerImpl.start(ServerImpl.java:362) at org.jboss.Main.boot(Main.java:200) at org.jboss.Main$1.run(Main.java:508) at java.lang.Thread.run(Thread.java:595)

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Confused Why I am getting C1010 error?

- by bluepixel

I have three files: Main, slist.h and slist.cpp can be seen at http://forums.devarticles.com/c-c-help-52/confused-why-i-am-getting-c2143-and-c1010-error-259574.html I'm trying to make a program where main reads the list of student names from a file (roster.txt) and inserts all the names in a list in ascending order. This is the full class roster list (notCheckedIN). From here I will read all students who have come to write the exams, each checkin will transfer their name to another list (in ascending order) called present. The final product is notCheckedIN will contain a list of all those students that did not write the exam and present will contain the list of all students who wrote the exam Main File: // Exam.cpp : Defines the entry point for the console application. #include "stdafx.h" #include "iostream" #include "iomanip" #include "fstream" #include "string" #include "slist.h" using namespace std; void OpenFile(ifstream&); void GetClassRoster(SortList&, ifstream&); void InputStuName(SortList&, SortList&); void UpdateList(SortList&, SortList&, string); void Print(SortList&, SortList&); const string END_DATA = "EndData"; int main() { ifstream roster; SortList notCheckedIn; //students present SortList present; //student absent OpenFile(roster); if(!roster) //Make sure file is opened return 1; GetClassRoster(notCheckedIn, roster); //insert the roster list into the notCheckedIn list InputStuName(present, notCheckedIn); Print(present, notCheckedIn); return 0; } void OpenFile(ifstream& roster) //Precondition: roster is pointing to file containing student anmes //Postcondition:IF file does not exist -> exit { string fileName = "roster.txt"; roster.open(fileName.c_str()); if(!roster) cout << "***ERROR CANNOT OPEN FILE :"<< fileName << "***" << endl; } void GetClassRoster(SortList& notCheckedIN, ifstream& roster) //Precondition:roster points to file containing list of student last name // && notCheckedIN is empty //Postcondition:notCheckedIN is filled with the names taken from roster.txt in ascending order { string name; roster >> name; while(roster) { notCheckedIN.Insert(name); roster >> name; } } void InputStuName(SortList& present, SortList& notCheckedIN) //Precondition: present list is empty initially and notCheckedIN list is full //Postcondition: repeated prompting to enter stuName // && notCheckedIN will delete all names found in present // && present will contain names present // && names not found in notCheckedIN will report Error { string stuName; cout << "Enter last name (Enter EndData if none to Enter): "; cin >> stuName; while(stuName!=END_DATA) { UpdateList(present, notCheckedIN, stuName); } } void UpdateList(SortList& present, SortList& notCheckedIN, string stuName) //Precondition:stuName is assigned //Postcondition:IF stuName is present, stuName is inserted in present list // && stuName is removed from the notCheckedIN list // ELSE stuName does not exist { if(notCheckedIN.isPresent(stuName)) { present.Insert(stuName); notCheckedIN.Delete(stuName); } else cout << "NAME IS NOT PRESENT" << endl; } void Print(SortList& present, SortList& notCheckedIN) //Precondition: present and notCheckedIN contains a list of student Names present/not present //Postcondition: content of present and notCheckedIN is printed { cout << "Candidates Present" << endl; present.Print(); cout << "Candidates Absent" << endl; notCheckedIN.Print(); } Header File: //Specification File: slist.h //This file gives the specifications of a list abstract data type //List items inserted will be in order //Class SortList, structured type used to represent an ADT using namespace std; const int MAX_LENGTH = 200; typedef string ItemType; //Class Object (class instance) SortList. Variable of class type. class SortList { //Class Member - components of a class, can be either data or functions public: //Constructor //Post-condition: Empty list is created SortList(); //Const member function. Compiler error occurs if any statement within tries to modify a private data bool isEmpty() const; //Post-condition: == true if list is empty // == false if list is not empty bool isFull() const; //Post-condition: == true if list is full // == false if list is full int Length() const; //Post-condition: size of list void Insert(ItemType item); //Precondition: NOT isFull() && item is assigned //Postcondition: item is in list && Length() = Length()@entry + 1 void Delete(ItemType item); //Precondition: NOT isEmpty() && item is assigned //Postcondition: // IF items is in list at entry // first occurance of item in list is removed // && Length() = Length()@entry -1; // ELSE // list is not changed bool isPresent(ItemType item) const; //Precondition: item is assigned //Postcondition: == true if item is present in list // == false if item is not present in list void Print() const; //Postcondition: All component of list have been output private: int length; ItemType data[MAX_LENGTH]; void BinSearch(ItemType, bool&, int&) const; }; Source File: //Implementation File: slist.cpp //This file gives the specifications of a list abstract data type //List items inserted will be in order //Class SortList, structured type used to represent an ADT #include "iostream" #include "slist.h" using namespace std; // int length; // ItemType data[MAX_SIZE]; //Class Object (class instance) SortList. Variable of class type. SortList::SortList() //Constructor //Post-condition: Empty list is created { length=0; } //Const member function. Compiler error occurs if any statement within tries to modify a private data bool SortList::isEmpty() const //Post-condition: == true if list is empty // == false if list is not empty { return(length==0); } bool SortList::isFull() const //Post-condition: == true if list is full // == false if list is full { return (length==(MAX_LENGTH-1)); } int SortList::Length() const //Post-condition: size of list { return length; } void SortList::Insert(ItemType item) //Precondition: NOT isFull() && item is assigned //Postcondition: item is in list && Length() = Length()@entry + 1 // && list componenet are in ascending order of value { int index; index = length -1; while(index >=0 && item<data[index]) { data[index+1]=data[index]; index--; } data[index+1]=item; length++; } void SortList:elete(ItemType item) //Precondition: NOT isEmpty() && item is assigned //Postcondition: // IF items is in list at entry // first occurance of item in list is removed // && Length() = Length()@entry -1; // && list components are in ascending order // ELSE data array is unchanged { bool found; int position; BinSearch(item,found,position); if (found) { for(int index = position; index < length; index++) data[index]=data[index+1]; length--; } } bool SortList::isPresent(ItemType item) const //Precondition: item is assigned && length <= MAX_LENGTH && items are in ascending order //Postcondition: true if item is found in the list // false if item is not found in the list { bool found; int position; BinSearch(item,found,position); return (found); } void SortList::Print() const //Postcondition: All component of list have been output { for(int x= 0; x<length; x++) cout << data[x] << endl; } void SortList::BinSearch(ItemType item, bool found, int position) const //Precondition: item contains item to be found // && item in the list is an ascending order //Postcondition: IF item is in list, position is returned // ELSE item does not exist in the list { int first = 0; int last = length -1; int middle; found = false; while(!found) { middle = (first+last)/2; if(data[middle]<item) first = middle+1; else if (data[middle] > item) last = middle -1; else found = true; } if(found) position = middle; } I cannot get rid of the C1010 error: fatal error C1010: unexpected end of file while looking for precompiled header. Did you forget to add '#include "stdafx.h"' to your source? Is there a way to get rid of this error? When I included "stdafx.h" I received the following 32 errors (which does not make sense to me why because I referred back to my manual on how to use Class method - everything looks a.ok.) Error 1 error C2871: 'std' : a namespace with this name does not exist c:\..\slist.h 6 Error 2 error C2146: syntax error : missing ';' before identifier 'ItemType' c:\..\slist.h 8 Error 3 error C4430: missing type specifier - int assumed. Note: C++ does not support default-int c:\..\slist.h 8 Error 4 error C4430: missing type specifier - int assumed. Note: C++ does not support default-int c:\..\slist.h 8 Error 5 error C2061: syntax error : identifier 'ItemType' c:\..\slist.h 30 Error 6 error C2061: syntax error : identifier 'ItemType' c:\..\slist.h 34 Error 7 error C2061: syntax error : identifier 'ItemType' c:\..\slist.h 43 Error 8 error C2146: syntax error : missing ';' before identifier 'data' c:\..\slist.h 52 Error 9 error C4430: missing type specifier - int assumed. Note: C++ does not support default-int c:\..\slist.h 52 Error 10 error C4430: missing type specifier - int assumed. Note: C++ does not support default-int c:\..\slist.h 52 Error 11 error C2061: syntax error : identifier 'ItemType' c:\..\slist.h 53 Error 12 error C2146: syntax error : missing ')' before identifier 'item' c:\..\slist.cpp 41 Error 13 error C2761: 'void SortList::Insert(void)' : member function redeclaration not allowed c:\..\slist.cpp 41 Error 14 error C2059: syntax error : ')' c:\..\slist.cpp 41 Error 15 error C2143: syntax error : missing ';' before '{' c:\..\slist.cpp 45 Error 16 error C2447: '{' : missing function header (old-style formal list?) c:\..\slist.cpp 45 Error 17 error C2146: syntax error : missing ')' before identifier 'item' c:\..\slist.cpp 57 Error 18 error C2761: 'void SortList:elete(void)' : member function redeclaration not allowed c:\..\slist.cpp 57 Error 19 error C2059: syntax error : ')' c:\..\slist.cpp 57 Error 20 error C2143: syntax error : missing ';' before '{' c:\..\slist.cpp 65 Error 21 error C2447: '{' : missing function header (old-style formal list?) c:\..\slist.cpp 65 Error 22 error C2146: syntax error : missing ')' before identifier 'item' c:\..\slist.cpp 79 Error 23 error C2761: 'bool SortList::isPresent(void) const' : member function redeclaration not allowed c:\..\slist.cpp 79 Error 24 error C2059: syntax error : ')' c:\..\slist.cpp 79 Error 25 error C2143: syntax error : missing ';' before '{' c:\..\slist.cpp 83 Error 26 error C2447: '{' : missing function header (old-style formal list?) c:\..\slist.cpp 83 Error 27 error C2065: 'data' : undeclared identifier c:\..\slist.cpp 95 Error 28 error C2146: syntax error : missing ')' before identifier 'item' c:\..\slist.cpp 98 Error 29 error C2761: 'void SortList::BinSearch(void) const' : member function redeclaration not allowed c:\..\slist.cpp 98 Error 30 error C2059: syntax error : ')' c:\..\slist.cpp 98 Error 31 error C2143: syntax error : missing ';' before '{' c:\..\slist.cpp 103 Error 32 error C2447: '{' : missing function header (old-style formal list?) c:\..\slist.cpp 103

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Java: Cannot find a method's symbol even though that method is declared later in the class. The remaining code is looking for a class.

- by Midimistro

This is an assignment that we use strings in Java to analyze a phone number. The error I am having is anything below tester=invalidCharacters(c); does not compile because every line past tester=invalidCharacters(c); is looking for a symbol or the class. In get invalidResults, all I am trying to do is evaluate a given string for non-alphabetical characters such as *,(,^,&,%,@,#,), and so on. What to answer: Why is it producing an error, what will work, and is there an easier method WITHOUT using regex. Here is the link to the assignment: http://cis.csuohio.edu/~hwang/teaching/cis260/assignments/assignment9.html public class PhoneNumber { private int areacode; private int number; private int ext; /////Constructors///// //Third Constructor (given one string arg) "xxx-xxxxxxx" where first three are numbers and the remaining (7) are numbers or letters public PhoneNumber(String newNumber){ //Note: Set default ext to 0 ext=0; ////Declare Temporary Storage and other variables//// //for the first three numbers String areaCodeString; //for the remaining seven characters String newNumberString; //For use in testing the second half of the string boolean containsLetters; boolean containsInvalid; /////Separate the two parts of string///// //Get the area code part of the string areaCodeString=newNumber.substring(0,2); //Convert the string and set it to the area code areacode=Integer.parseInt(areaCodeString); //Skip the "-" and Get the remaining part of the string newNumberString=newNumber.substring(4); //Create an array of characters from newNumberString to reuse in later methods for int length=newNumberString.length(); char [] myCharacters= new char [length]; int i; for (i=0;i<length;i++){ myCharacters [i]=newNumberString.charAt(i); } //Test if newNumberString contains letters & converting them into numbers String reNewNumber=""; //Test for invalid characters containsInvalid=getInvalidResults(newNumberString,length); if (containsInvalid==false){ containsLetters=getCharResults(newNumberString,length); if (containsLetters==true){ for (i=0;i<length;i++){ myCharacters [i]=(char)convertLetNum((myCharacters [i])); reNewNumber=reNewNumber+myCharacters[i]; } } } if (containsInvalid==false){ number=Integer.parseInt(reNewNumber); } else{ System.out.println("Error!"+"\t"+newNumber+" contains illegal characters. This number will be ignored and skipped."); } } //////Primary Methods/Behaviors/////// //Compare this phone number with the one passed by the caller public boolean equals(PhoneNumber pn){ boolean equal; String concat=(areacode+"-"+number); String pN=pn.toString(); if (concat==pN){ equal=true; } else{ equal=false; } return equal; } //Convert the stored number to a certain string depending on extension public String toString(){ String returned; if(ext==0){ returned=(areacode+"-"+number); } else{ returned=(areacode+"-"+number+" ext "+ext); } return returned; } //////Secondary Methods/////// //Method for testing if the second part of the string contains any letters public static boolean getCharResults(String newNumString,int getLength){ //Recreate a character array int i; char [] myCharacters= new char [getLength]; for (i=0;i<getLength;i++){ myCharacters [i]=newNumString.charAt(i); } boolean doesContainLetter=false; int j; for (j=0;j<getLength;j++){ if ((Character.isDigit(myCharacters[j])==true)){ doesContainLetter=false; } else{ doesContainLetter=true; return doesContainLetter; } } return doesContainLetter; } //Method for testing if the second part of the string contains any letters public static boolean getInvalidResults(String newNumString,int getLength){ boolean doesContainInvalid=false; int i; char c; boolean tester; char [] invalidCharacters= new char [getLength]; for (i=0;i<getLength;i++){ invalidCharacters [i]=newNumString.charAt(i); c=invalidCharacters [i]; tester=invalidCharacters(c); if(tester==true)){ doesContainInvalid=false; } else{ doesContainInvalid=true; return doesContainInvalid; } } return doesContainInvalid; } //Method for evaluating string for invalid characters public boolean invalidCharacters(char letter){ boolean returnNum=false; switch (letter){ case 'A': return returnNum; case 'B': return returnNum; case 'C': return returnNum; case 'D': return returnNum; case 'E': return returnNum; case 'F': return returnNum; case 'G': return returnNum; case 'H': return returnNum; case 'I': return returnNum; case 'J': return returnNum; case 'K': return returnNum; case 'L': return returnNum; case 'M': return returnNum; case 'N': return returnNum; case 'O': return returnNum; case 'P': return returnNum; case 'Q': return returnNum; case 'R': return returnNum; case 'S': return returnNum; case 'T': return returnNum; case 'U': return returnNum; case 'V': return returnNum; case 'W': return returnNum; case 'X': return returnNum; case 'Y': return returnNum; case 'Z': return returnNum; default: return true; } } //Method for converting letters to numbers public int convertLetNum(char letter){ int returnNum; switch (letter){ case 'A': returnNum=2;return returnNum; case 'B': returnNum=2;return returnNum; case 'C': returnNum=2;return returnNum; case 'D': returnNum=3;return returnNum; case 'E': returnNum=3;return returnNum; case 'F': returnNum=3;return returnNum; case 'G': returnNum=4;return returnNum; case 'H': returnNum=4;return returnNum; case 'I': returnNum=4;return returnNum; case 'J': returnNum=5;return returnNum; case 'K': returnNum=5;return returnNum; case 'L': returnNum=5;return returnNum; case 'M': returnNum=6;return returnNum; case 'N': returnNum=6;return returnNum; case 'O': returnNum=6;return returnNum; case 'P': returnNum=7;return returnNum; case 'Q': returnNum=7;return returnNum; case 'R': returnNum=7;return returnNum; case 'S': returnNum=7;return returnNum; case 'T': returnNum=8;return returnNum; case 'U': returnNum=8;return returnNum; case 'V': returnNum=8;return returnNum; case 'W': returnNum=9;return returnNum; case 'X': returnNum=9;return returnNum; case 'Y': returnNum=9;return returnNum; case 'Z': returnNum=9;return returnNum; default: return 0; } } } Note: Please Do not use this program to cheat in your own class. To ensure of this, I will take this question down if it has not been answered by the end of 2013, if I no longer need an explanation for it, or if the term for the class has ended.

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ActionResult types in MVC2

- by rajbk

In ASP.NET MVC, incoming browser requests gets mapped to a controller action method. The action method returns a type of ActionResult in response to the browser request. A basic example is shown below: public class HomeController : Controller { public ActionResult Index() { return View(); } } Here we have an action method called Index that returns an ActionResult. Inside the method we call the View() method on the base Controller. The View() method, as you will see shortly, is a method that returns a ViewResult. The ActionResult class is the base class for different controller results. The following diagram shows the types derived from the ActionResult type. ASP.NET has a description of these methods ContentResult – Represents a text result. EmptyResult – Represents no result. FileContentResult – Represents a downloadable file (with the binary content). FilePathResult – Represents a downloadable file (with a path). FileStreamResult – Represents a downloadable file (with a file stream). JavaScriptResult – Represents a JavaScript script. JsonResult – Represents a JavaScript Object Notation result that can be used in an AJAX application. PartialViewResult – Represents HTML and markup rendered by a partial view. RedirectResult – Represents a redirection to a new URL. RedirectToRouteResult – Represents a result that performs a redirection by using the specified route values dictionary. ViewResult – Represents HTML and markup rendered by a view. To return the types shown above, you call methods that are available in the Controller base class. A list of these methods are shown below. Methods without an ActionResult return type The MVC framework will translate action methods that do not return an ActionResult into one. Consider the HomeController below which has methods that do not return any ActionResult types. The methods defined return an int, object and void respectfully. public class HomeController : Controller { public int Add(int x, int y) { return x + y; } public Employee GetEmployee() { return new Employee(); } public void DoNothing() { } } When a request comes in, the Controller class hands internally uses a ControllerActionInvoker class which inspects the action parameters and invokes the correct action method. The CreateActionResult method in the ControllerActionInvoker class is used to return an ActionResult. This method is shown below. If the result of the action method is null, an EmptyResult instance is returned. If the result is not of type ActionResult, the result is converted to a string and returned as a ContentResult. protected virtual ActionResult CreateActionResult(ControllerContext controllerContext, ActionDescriptor actionDescriptor, object actionReturnValue) { if (actionReturnValue == null) { return new EmptyResult(); } ActionResult actionResult = (actionReturnValue as ActionResult) ?? new ContentResult { Content = Convert.ToString(actionReturnValue, CultureInfo.InvariantCulture) }; return actionResult; } In the HomeController class above, the DoNothing method will return an instance of the EmptyResult() Renders an empty webpage the GetEmployee() method will return a ContentResult which contains a string that represents the current object Renders the text “MyNameSpace.Controllers.Employee” without quotes. the Add method for a request of /home/add?x=3&y=5 returns a ContentResult Renders the text “8” without quotes. Unit Testing The nice thing about the ActionResult types is in unit testing the controller. We can, without starting a web server, create an instance of the Controller, call the methods and verify that the type returned is the expected ActionResult type. We can then inspect the returned type properties and confirm that it contains the expected values. Enjoy! Sulley: Hey, Mike, this might sound crazy but I don't think that kid's dangerous. Mike: Really? Well, in that case, let's keep it. I always wanted a pet that could kill me.

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Optional Parameters and Named Arguments in C# 4 (and a cool scenario w/ ASP.NET MVC 2)

- by ScottGu

[In addition to blogging, I am also now using Twitter for quick updates and to share links. Follow me at: twitter.com/scottgu] This is the seventeenth in a series of blog posts I’m doing on the upcoming VS 2010 and .NET 4 release. Today’s post covers two new language feature being added to C# 4.0 – optional parameters and named arguments – as well as a cool way you can take advantage of optional parameters (both in VB and C#) with ASP.NET MVC 2. Optional Parameters in C# 4.0 C# 4.0 now supports using optional parameters with methods, constructors, and indexers (note: VB has supported optional parameters for awhile). Parameters are optional when a default value is specified as part of a declaration. For example, the method below takes two parameters – a “category” string parameter, and a “pageIndex” integer parameter. The “pageIndex” parameter has a default value of 0, and as such is an optional parameter: When calling the above method we can explicitly pass two parameters to it: Or we can omit passing the second optional parameter – in which case the default value of 0 will be passed: Note that VS 2010’s Intellisense indicates when a parameter is optional, as well as what its default value is when statement completion is displayed: Named Arguments and Optional Parameters in C# 4.0 C# 4.0 also now supports the concept of “named arguments”. This allows you to explicitly name an argument you are passing to a method – instead of just identifying it by argument position. For example, I could write the code below to explicitly identify the second argument passed to the GetProductsByCategory method by name (making its usage a little more explicit): Named arguments come in very useful when a method supports multiple optional parameters, and you want to specify which arguments you are passing. For example, below we have a method DoSomething that takes two optional parameters: We could use named arguments to call the above method in any of the below ways: Because both parameters are optional, in cases where only one (or zero) parameters is specified then the default value for any non-specified arguments is passed. ASP.NET MVC 2 and Optional Parameters One nice usage scenario where we can now take advantage of the optional parameter support of VB and C# is with ASP.NET MVC 2’s input binding support to Action methods on Controller classes. For example, consider a scenario where we want to map URLs like “Products/Browse/Beverages” or “Products/Browse/Deserts” to a controller action method. We could do this by writing a URL routing rule that maps the URLs to a method like so: We could then optionally use a “page” querystring value to indicate whether or not the results displayed by the Browse method should be paged – and if so which page of the results should be displayed. For example: /Products/Browse/Beverages?page=2. With ASP.NET MVC 1 you would typically handle this scenario by adding a “page” parameter to the action method and make it a nullable int (which means it will be null if the “page” querystring value is not present). You could then write code like below to convert the nullable int to an int – and assign it a default value if it was not present in the querystring: With ASP.NET MVC 2 you can now take advantage of the optional parameter support in VB and C# to express this behavior more concisely and clearly. Simply declare the action method parameter as an optional parameter with a default value: C# VB If the “page” value is present in the querystring (e.g. /Products/Browse/Beverages?page=22) then it will be passed to the action method as an integer. If the “page” value is not in the querystring (e.g. /Products/Browse/Beverages) then the default value of 0 will be passed to the action method. This makes the code a little more concise and readable. Summary There are a bunch of great new language features coming to both C# and VB with VS 2010. The above two features (optional parameters and named parameters) are but two of them. I’ll blog about more in the weeks and months ahead. If you are looking for a good book that summarizes all the language features in C# (including C# 4.0), as well provides a nice summary of the core .NET class libraries, you might also want to check out the newly released C# 4.0 in a Nutshell book from O’Reilly: It does a very nice job of packing a lot of content in an easy to search and find samples format. Hope this helps, Scott

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Fed Authentication Methods in OIF / IdP

- by Damien Carru

This article is a continuation of my previous entry where I explained how OIF/IdP leverages OAM to authenticate users at runtime: OIF/IdP internally forwards the user to OAM and indicates which Authentication Scheme should be used to challenge the user if needed OAM determine if the user should be challenged (user already authenticated, session timed out or not, session authentication level equal or higher than the level of the authentication scheme specified by OIF/IdP…) After identifying the user, OAM internally forwards the user back to OIF/IdP OIF/IdP can resume its operation In this article, I will discuss how OIF/IdP can be configured to map Federation Authentication Methods to OAM Authentication Schemes: When processing an Authn Request, where the SP requests a specific Federation Authentication Method with which the user should be challenged When sending an Assertion, where OIF/IdP sets the Federation Authentication Method in the Assertion Enjoy the reading! Overview The various Federation protocols support mechanisms allowing the partners to exchange information on: How the user should be challenged, when the SP/RP makes a request How the user was challenged, when the IdP/OP issues an SSO response When a remote SP partner redirects the user to OIF/IdP for Federation SSO, the message might contain data requesting how the user should be challenged by the IdP: this is treated as the Requested Federation Authentication Method. OIF/IdP will need to map that Requested Federation Authentication Method to a local Authentication Scheme, and then invoke OAM for user authentication/challenge with the mapped Authentication Scheme. OAM would authenticate the user if necessary with the scheme specified by OIF/IdP. Similarly, when an IdP issues an SSO response, most of the time it will need to include an identifier representing how the user was challenged: this is treated as the Federation Authentication Method. When OIF/IdP issues an Assertion, it will evaluate the Authentication Scheme with which OAM identified the user: If the Authentication Scheme can be mapped to a Federation Authentication Method, then OIF/IdP will use the result of that mapping in the outgoing SSO response: AuthenticationStatement in the SAML Assertion OpenID Response, if PAPE is enabled If the Authentication Scheme cannot be mapped, then OIF/IdP will set the Federation Authentication Method as the Authentication Scheme name in the outgoing SSO response: AuthenticationStatement in the SAML Assertion OpenID Response, if PAPE is enabled Mappings In OIF/IdP, the mapping between Federation Authentication Methods and Authentication Schemes has the following rules: One Federation Authentication Method can be mapped to several Authentication Schemes In a Federation Authentication Method <-> Authentication Schemes mapping, a single Authentication Scheme is marked as the default scheme that will be used to authenticate a user, if the SP/RP partner requests the user to be authenticated via a specific Federation Authentication Method An Authentication Scheme can be mapped to a single Federation Authentication Method Let’s examine the following example and the various use cases, based on the SAML 2.0 protocol: Mappings defined as: urn:oasis:names:tc:SAML:2.0:ac:classes:PasswordProtectedTransport mapped to LDAPScheme, marked as the default scheme used for authentication BasicScheme urn:oasis:names:tc:SAML:2.0:ac:classes:X509 mapped to X509Scheme, marked as the default scheme used for authentication Use cases: SP sends an AuthnRequest specifying urn:oasis:names:tc:SAML:2.0:ac:classes:X509 as the RequestedAuthnContext: OIF/IdP will authenticate the use with X509Scheme since it is the default scheme mapped for that method. SP sends an AuthnRequest specifying urn:oasis:names:tc:SAML:2.0:ac:classes:PasswordProtectedTransport as the RequestedAuthnContext: OIF/IdP will authenticate the use with LDAPScheme since it is the default scheme mapped for that method, not the BasicScheme SP did not request any specific methods, and user was authenticated with BasisScheme: OIF/IdP will issue an Assertion with urn:oasis:names:tc:SAML:2.0:ac:classes:PasswordProtectedTransport as the FederationAuthenticationMethod SP did not request any specific methods, and user was authenticated with LDAPScheme: OIF/IdP will issue an Assertion with urn:oasis:names:tc:SAML:2.0:ac:classes:PasswordProtectedTransport as the FederationAuthenticationMethod SP did not request any specific methods, and user was authenticated with BasisSessionlessScheme: OIF/IdP will issue an Assertion with BasisSessionlessScheme as the FederationAuthenticationMethod, since that scheme could not be mapped to any Federation Authentication Method (in this case, the administrator would need to correct that and create a mapping) Configuration Mapping Federation Authentication Methods to OAM Authentication Schemes is protocol dependent, since the methods are defined in the various protocols (SAML 2.0, SAML 1.1, OpenID 2.0). As such, the WLST commands to set those mappings will involve: Either the SP Partner Profile and affect all Partners referencing that profile, which do not override the Federation Authentication Method to OAM Authentication Scheme mappings Or the SP Partner entry, which will only affect the SP Partner It is important to note that if an SP Partner is configured to define one or more Federation Authentication Method to OAM Authentication Scheme mappings, then all the mappings defined in the SP Partner Profile will be ignored. Authentication Schemes As discussed in the previous article, during Federation SSO, OIF/IdP will internally forward the user to OAM for authentication/verification and specify which Authentication Scheme to use. OAM will determine if a user needs to be challenged: If the user is not authenticated yet If the user is authenticated but the session timed out If the user is authenticated, but the authentication scheme level of the original authentication is lower than the level of the authentication scheme requested by OIF/IdP So even though an SP requests a specific Federation Authentication Method to be used to challenge the user, if that method is mapped to an Authentication Scheme and that at runtime OAM deems that the user does not need to be challenged with that scheme (because the user is already authenticated, session did not time out, and the session authn level is equal or higher than the one for the specified Authentication Scheme), the flow won’t result in a challenge operation. Protocols SAML 2.0 The SAML 2.0 specifications define the following Federation Authentication Methods for SAML 2.0 flows: urn:oasis:names:tc:SAML:2.0:ac:classes:unspecified urn:oasis:names:tc:SAML:2.0:ac:classes:InternetProtocol urn:oasis:names:tc:SAML:2.0:ac:classes:Telephony urn:oasis:names:tc:SAML:2.0:ac:classes:MobileOneFactorUnregistered urn:oasis:names:tc:SAML:2.0:ac:classes:PersonalTelephony urn:oasis:names:tc:SAML:2.0:ac:classes:PreviousSession urn:oasis:names:tc:SAML:2.0:ac:classes:MobileOneFactorContract urn:oasis:names:tc:SAML:2.0:ac:classes:Smartcard urn:oasis:names:tc:SAML:2.0:ac:classes:Password urn:oasis:names:tc:SAML:2.0:ac:classes:InternetProtocolPassword urn:oasis:names:tc:SAML:2.0:ac:classes:X509 urn:oasis:names:tc:SAML:2.0:ac:classes:TLSClient urn:oasis:names:tc:SAML:2.0:ac:classes:PGP urn:oasis:names:tc:SAML:2.0:ac:classes:SPKI urn:oasis:names:tc:SAML:2.0:ac:classes:XMLDSig urn:oasis:names:tc:SAML:2.0:ac:classes:SoftwarePKI urn:oasis:names:tc:SAML:2.0:ac:classes:Kerberos urn:oasis:names:tc:SAML:2.0:ac:classes:PasswordProtectedTransport urn:oasis:names:tc:SAML:2.0:ac:classes:SecureRemotePassword urn:oasis:names:tc:SAML:2.0:ac:classes:NomadTelephony urn:oasis:names:tc:SAML:2.0:ac:classes:AuthenticatedTelephony urn:oasis:names:tc:SAML:2.0:ac:classes:MobileTwoFactorUnregistered urn:oasis:names:tc:SAML:2.0:ac:classes:MobileTwoFactorContract urn:oasis:names:tc:SAML:2.0:ac:classes:SmartcardPKI urn:oasis:names:tc:SAML:2.0:ac:classes:TimeSyncToken Out of the box, OIF/IdP has the following mappings for the SAML 2.0 protocol: Only urn:oasis:names:tc:SAML:2.0:ac:classes:PasswordProtectedTransport is defined This Federation Authentication Method is mapped to: LDAPScheme, marked as the default scheme used for authentication FAAuthScheme BasicScheme BasicFAScheme This mapping is defined in the saml20-sp-partner-profile SP Partner Profile which is the default OOTB SP Partner Profile for SAML 2.0 An example of an AuthnRequest message sent by an SP to an IdP with the SP requesting a specific Federation Authentication Method to be used to challenge the user would be: <samlp:AuthnRequest xmlns:samlp="urn:oasis:names:tc:SAML:2.0:protocol" Destination="https://idp.com/oamfed/idp/samlv20" ID="id-8bWn-A9o4aoMl3Nhx1DuPOOjawc-" IssueInstant="2014-03-21T20:51:11Z" Version="2.0"> <saml:Issuer ...>https://acme.com/sp</saml:Issuer> <samlp:NameIDPolicy AllowCreate="false" Format="urn:oasis:names:tc:SAML:1.1:nameid-format:unspecified"/> <samlp:RequestedAuthnContext Comparison="minimum"> <saml:AuthnContextClassRef xmlns:saml="urn:oasis:names:tc:SAML:2.0:assertion"> urn:oasis:names:tc:SAML:2.0:ac:classes:PasswordProtectedTransport </saml:AuthnContextClassRef> </samlp:RequestedAuthnContext></samlp:AuthnRequest> An example of an Assertion issued by an IdP would be: <samlp:Response ...> <saml:Issuer ...>https://idp.com/oam/fed</saml:Issuer> <samlp:Status> <samlp:StatusCode Value="urn:oasis:names:tc:SAML:2.0:status:Success"/> </samlp:Status> <saml:Assertion ...> <saml:Issuer ...>https://idp.com/oam/fed</saml:Issuer> <dsig:Signature> ... </dsig:Signature> <saml:Subject> <saml:NameID ...>[email protected]</saml:NameID> <saml:SubjectConfirmation Method="urn:oasis:names:tc:SAML:2.0:cm:bearer"> <saml:SubjectConfirmationData .../> </saml:SubjectConfirmation> </saml:Subject> <saml:Conditions ...> <saml:AudienceRestriction> <saml:Audience>https://acme.com/sp</saml:Audience> </saml:AudienceRestriction> </saml:Conditions> <saml:AuthnStatement AuthnInstant="2014-03-21T20:53:55Z" SessionIndex="id-6i-Dm0yB-HekG6cejktwcKIFMzYE8Yrmqwfd0azz" SessionNotOnOrAfter="2014-03-21T21:53:55Z"> <saml:AuthnContext> <saml:AuthnContextClassRef> urn:oasis:names:tc:SAML:2.0:ac:classes:PasswordProtectedTransport </saml:AuthnContextClassRef> </saml:AuthnContext> </saml:AuthnStatement> </saml:Assertion></samlp:Response> An administrator would be able to specify a mapping between a SAML 2.0 Federation Authentication Method and one or more OAM Authentication Schemes SAML 1.1 The SAML 1.1 specifications define the following Federation Authentication Methods for SAML 1.1 flows: urn:oasis:names:tc:SAML:1.0:am:unspecified urn:oasis:names:tc:SAML:1.0:am:HardwareToken urn:oasis:names:tc:SAML:1.0:am:password urn:oasis:names:tc:SAML:1.0:am:X509-PKI urn:ietf:rfc:2246 urn:oasis:names:tc:SAML:1.0:am:PGP urn:oasis:names:tc:SAML:1.0:am:SPKI urn:ietf:rfc:3075 urn:oasis:names:tc:SAML:1.0:am:XKMS urn:ietf:rfc:1510 urn:ietf:rfc:2945 Out of the box, OIF/IdP has the following mappings for the SAML 1.1 protocol: Only urn:oasis:names:tc:SAML:1.0:am:password is defined This Federation Authentication Method is mapped to: LDAPScheme, marked as the default scheme used for authentication FAAuthScheme BasicScheme BasicFAScheme This mapping is defined in the saml11-sp-partner-profile SP Partner Profile which is the default OOTB SP Partner Profile for SAML 1.1 An example of an Assertion issued by an IdP would be: <samlp:Response ...> <samlp:Status> <samlp:StatusCode Value="samlp:Success"/> </samlp:Status> <saml:Assertion Issuer="https://idp.com/oam/fed" ...> <saml:Conditions ...> <saml:AudienceRestriction> <saml:Audience>https://acme.com/sp/ssov11</saml:Audience> </saml:AudienceRestriction> </saml:Conditions> <saml:AuthnStatement AuthenticationInstant="2014-03-21T20:53:55Z" AuthenticationMethod="urn:oasis:names:tc:SAML:1.0:am:password"> <saml:Subject> <saml:NameID ...>[email protected]</saml:NameID> <saml:SubjectConfirmation> <saml:ConfirmationMethod> urn:oasis:names:tc:SAML:1.0:cm:bearer </saml:ConfirmationMethod> </saml:SubjectConfirmation> </saml:Subject> </saml:AuthnStatement> <dsig:Signature> ... </dsig:Signature> </saml:Assertion></samlp:Response> Note: SAML 1.1 does not define an AuthnRequest message. An administrator would be able to specify a mapping between a SAML 1.1 Federation Authentication Method and one or more OAM Authentication Schemes OpenID 2.0 The OpenID 2.0 PAPE specifications define the following Federation Authentication Methods for OpenID 2.0 flows: http://schemas.openid.net/pape/policies/2007/06/phishing-resistant http://schemas.openid.net/pape/policies/2007/06/multi-factor http://schemas.openid.net/pape/policies/2007/06/multi-factor-physical Out of the box, OIF/IdP does not define any mappings for the OpenID 2.0 Federation Authentication Methods. For OpenID 2.0, the configuration will involve mapping a list of OpenID 2.0 policies to a list of Authentication Schemes. An example of an OpenID 2.0 Request message sent by an SP/RP to an IdP/OP would be: https://idp.com/openid?openid.ns=http%3A%2F%2Fspecs.openid.net%2Fauth%2F2.0&openid.mode=checkid_setup&openid.claimed_id=http%3A%2F%2Fspecs.openid.net%2Fauth%2F2.0%2Fidentifier_select&openid.identity=http%3A%2F%2Fspecs.openid.net%2Fauth%2F2.0%2Fidentifier_select&openid.assoc_handle=id-6a5S6zhAKaRwQNUnjTKROREdAGSjWodG1el4xyz3&openid.return_to=https%3A%2F%2Facme.com%2Fopenid%3Frefid%3Did-9PKVXZmRxAeDYcgLqPm36ClzOMA-&openid.realm=https%3A%2F%2Facme.com%2Fopenid&openid.ns.ax=http%3A%2F%2Fopenid.net%2Fsrv%2Fax%2F1.0&openid.ax.mode=fetch_request&openid.ax.type.attr0=http%3A%2F%2Faxschema.org%2Fcontact%2Femail&openid.ax.if_available=attr0&openid.ns.pape=http%3A%2F%2Fspecs.openid.net%2Fextensions%2Fpape%2F1.0&openid.pape.max_auth_age=0 An example of an Open ID 2.0 SSO Response issued by an IdP/OP would be: https://acme.com/openid?refid=id-9PKVXZmRxAeDYcgLqPm36ClzOMA-&openid.ns=http%3A%2F%2Fspecs.openid.net%2Fauth%2F2.0&openid.mode=id_res&openid.op_endpoint=https%3A%2F%2Fidp.com%2Fopenid&openid.claimed_id=https%3A%2F%2Fidp.com%2Fopenid%3Fid%3Did-38iCmmlAVEXPsFjnFVKArfn5RIiF75D5doorhEgqqPM%3D&openid.identity=https%3A%2F%2Fidp.com%2Fopenid%3Fid%3Did-38iCmmlAVEXPsFjnFVKArfn5RIiF75D5doorhEgqqPM%3D&openid.return_to=https%3A%2F%2Facme.com%2Fopenid%3Frefid%3Did-9PKVXZmRxAeDYcgLqPm36ClzOMA-&openid.response_nonce=2014-03-24T19%3A20%3A06Zid-YPa2kTNNFftZkgBb460jxJGblk2g--iNwPpDI7M1&openid.assoc_handle=id-6a5S6zhAKaRwQNUnjTKROREdAGSjWodG1el4xyz3&openid.ns.ax=http%3A%2F%2Fopenid.net%2Fsrv%2Fax%2F1.0&openid.ax.mode=fetch_response&openid.ax.type.attr0=http%3A%2F%2Fsession%2Fcount&openid.ax.value.attr0=1&openid.ax.type.attr1=http%3A%2F%2Fopenid.net%2Fschema%2FnamePerson%2Ffriendly&openid.ax.value.attr1=My+name+is+Bobby+Smith&openid.ax.type.attr2=http%3A%2F%2Fschemas.openid.net%2Fax%2Fapi%2Fuser_id&openid.ax.value.attr2=bob&openid.ax.type.attr3=http%3A%2F%2Faxschema.org%2Fcontact%2Femail&openid.ax.value.attr3=bob%40oracle.com&openid.ax.type.attr4=http%3A%2F%2Fsession%2Fipaddress&openid.ax.value.attr4=10.145.120.253&openid.ns.pape=http%3A%2F%2Fspecs.openid.net%2Fextensions%2Fpape%2F1.0&openid.pape.auth_time=2014-03-24T19%3A20%3A05Z&openid.pape.auth_policies=http%3A%2F%2Fschemas.openid.net%2Fpape%2Fpolicies%2F2007%2F06%2Fphishing-resistant&openid.signed=op_endpoint%2Cclaimed_id%2Cidentity%2Creturn_to%2Cresponse_nonce%2Cassoc_handle%2Cns.ax%2Cax.mode%2Cax.type.attr0%2Cax.value.attr0%2Cax.type.attr1%2Cax.value.attr1%2Cax.type.attr2%2Cax.value.attr2%2Cax.type.attr3%2Cax.value.attr3%2Cax.type.attr4%2Cax.value.attr4%2Cns.pape%2Cpape.auth_time%2Cpape.auth_policies&openid.sig=mYMgbGYSs22l8e%2FDom9NRPw15u8%3D In the next article, I will provide examples on how to configure OIF/IdP for the various protocols, to map OAM Authentication Schemes to Federation Authentication Methods.Cheers,Damien Carru

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An abundance of LINQ queries and expressions using both the query and method syntax.

- by nikolaosk

In this post I will be writing LINQ queries against an array of strings, an array of integers.Moreover I will be using LINQ to query an SQL Server database. I can use LINQ against arrays since the array of strings/integers implement the IENumerable interface. I thought it would be a good idea to use both the method syntax and the query syntax. There are other places on the net where you can find examples of LINQ queries but I decided to create a big post using as many LINQ examples as possible. We...(read more)

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What do the 4 keyboard input method systems in 10.04 mean?

- by Android Eve

I am trying to install another language support (in addition to the default US). Checking that language checkbox in "Install / Remove Languages..." wasn't too difficult. :) But now I want to add keyboard support, too, for that language. Again, I am prompted with a nice listbox with the following 4 options: none ibus lo-gtk th-gtk But I have no idea what these mean. I googled "ubuntu 10.04 keyboard input method system none ibus lo-gtk th-gtk" but all I could find was descriptions of problems, not an actual definition. Could you please point me to a webpage where I can learn about the meanings of these 4 different methods and +'s and -'s of each?

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Z600 Workstation ACPI Fan Noise

- by dpb

Hi -- I have an HP z600 workstation that has the FAN running full when idle. In fact, after the boot, the fan never slows down or varies. I looked in dmesg, and noticed this: [ 1.516778] ACPI Error (dsfield-0143): [CAPD] Namespace lookup failure, AE_ALREADY_EXISTS [ 1.516781] ACPI Error (psparse-0537): Method parse/execution failed [\_SB_.PCI0._OSC] (Node ffff8801b8c4e3e0), AE_ALREADY_EXISTS [ 1.516786] ACPI: Marking method _OSC as Serialized because of AE_ALREADY_EXISTS error [ 1.519868] ACPI Error (dsfield-0143): [CAPD] Namespace lookup failure, AE_ALREADY_EXISTS [ 1.519872] ACPI Error (psparse-0537): Method parse/execution failed [\_SB_.PCI0._OSC] (Node ffff8801b8c4e3e0), AE_ALREADY_EXISTS [ 1.624638] ACPI Error (dsfield-0143): [CAPD] Namespace lookup failure, AE_ALREADY_EXISTS [ 1.624642] ACPI Error (psparse-0537): Method parse/execution failed [\_SB_.PCI0._OSC] (Node ffff8801b8c4e3e0), AE_ALREADY_EXISTS [ 1.624726] ACPI Error (dsfield-0143): [CAPD] Namespace lookup failure, AE_ALREADY_EXISTS [ 1.624729] ACPI Error (psparse-0537): Method parse/execution failed [\_SB_.PCI0._OSC] (Node ffff8801b8c4e3e0), AE_ALREADY_EXISTS [ 1.624802] ACPI Error (dsfield-0143): [CAPD] Namespace lookup failure, AE_ALREADY_EXISTS [ 1.624805] ACPI Error (psparse-0537): Method parse/execution failed [\_SB_.PCI0._OSC] (Node ffff8801b8c4e3e0), AE_ALREADY_EXISTS [ 1.624895] ACPI Error (dsfield-0143): [CAPD] Namespace lookup failure, AE_ALREADY_EXISTS [ 1.624898] ACPI Error (psparse-0537): Method parse/execution failed [\_SB_.PCI0._OSC] (Node ffff8801b8c4e3e0), AE_ALREADY_EXISTS [ 1.624977] ACPI Error (dsfield-0143): [CAPD] Namespace lookup failure, AE_ALREADY_EXISTS [ 1.624981] ACPI Error (psparse-0537): Method parse/execution failed [\_SB_.PCI0._OSC] (Node ffff8801b8c4e3e0), AE_ALREADY_EXISTS [ 1.625070] ACPI Error (dsfield-0143): [CAPD] Namespace lookup failure, AE_ALREADY_EXISTS [ 1.625074] ACPI Error (psparse-0537): Method parse/execution failed [\_SB_.PCI0._OSC] (Node ffff8801b8c4e3e0), AE_ALREADY_EXISTS [ 1.625153] ACPI Error (dsfield-0143): [CAPD] Namespace lookup failure, AE_ALREADY_EXISTS [ 1.625157] ACPI Error (psparse-0537): Method parse/execution failed [\_SB_.PCI0._OSC] (Node ffff8801b8c4e3e0), AE_ALREADY_EXISTS Anyone know what could be done to fix this?

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Understanding C# async / await (2) Awaitable / Awaiter Pattern

- by Dixin

What is awaitable Part 1 shows that any Task is awaitable. Actually there are other awaitable types. Here is an example: Task<int> task = new Task<int>(() => 0); int result = await task.ConfigureAwait(false); // Returns a ConfiguredTaskAwaitable<TResult>. The returned ConfiguredTaskAwaitable<TResult> struct is awaitable. And it is not Task at all: public struct ConfiguredTaskAwaitable<TResult> { private readonly ConfiguredTaskAwaiter m_configuredTaskAwaiter; internal ConfiguredTaskAwaitable(Task<TResult> task, bool continueOnCapturedContext) { this.m_configuredTaskAwaiter = new ConfiguredTaskAwaiter(task, continueOnCapturedContext); } public ConfiguredTaskAwaiter GetAwaiter() { return this.m_configuredTaskAwaiter; } } It has one GetAwaiter() method. Actually in part 1 we have seen that Task has GetAwaiter() method too: public class Task { public TaskAwaiter GetAwaiter() { return new TaskAwaiter(this); } } public class Task<TResult> : Task { public new TaskAwaiter<TResult> GetAwaiter() { return new TaskAwaiter<TResult>(this); } } Task.Yield() is a another example: await Task.Yield(); // Returns a YieldAwaitable. The returned YieldAwaitable is not Task either: public struct YieldAwaitable { public YieldAwaiter GetAwaiter() { return default(YieldAwaiter); } } Again, it just has one GetAwaiter() method. In this article, we will look at what is awaitable. The awaitable / awaiter pattern By observing different awaitable / awaiter types, we can tell that an object is awaitable if It has a GetAwaiter() method (instance method or extension method); Its GetAwaiter() method returns an awaiter. An object is an awaiter if: It implements INotifyCompletion or ICriticalNotifyCompletion interface; It has an IsCompleted, which has a getter and returns a Boolean; it has a GetResult() method, which returns void, or a result. This awaitable / awaiter pattern is very similar to the iteratable / iterator pattern. Here is the interface definitions of iteratable / iterator: public interface IEnumerable { IEnumerator GetEnumerator(); } public interface IEnumerator { object Current { get; } bool MoveNext(); void Reset(); } public interface IEnumerable<out T> : IEnumerable { IEnumerator<T> GetEnumerator(); } public interface IEnumerator<out T> : IDisposable, IEnumerator { T Current { get; } } In case you are not familiar with the out keyword, please find out the explanation in Understanding C# Covariance And Contravariance (2) Interfaces. The “missing” IAwaitable / IAwaiter interfaces Similar to IEnumerable and IEnumerator interfaces, awaitable / awaiter can be visualized by IAwaitable / IAwaiter interfaces too. This is the non-generic version: public interface IAwaitable { IAwaiter GetAwaiter(); } public interface IAwaiter : INotifyCompletion // or ICriticalNotifyCompletion { // INotifyCompletion has one method: void OnCompleted(Action continuation); // ICriticalNotifyCompletion implements INotifyCompletion, // also has this method: void UnsafeOnCompleted(Action continuation); bool IsCompleted { get; } void GetResult(); } Please notice GetResult() returns void here. Task.GetAwaiter() / TaskAwaiter.GetResult() is of such case. And this is the generic version: public interface IAwaitable<out TResult> { IAwaiter<TResult> GetAwaiter(); } public interface IAwaiter<out TResult> : INotifyCompletion // or ICriticalNotifyCompletion { bool IsCompleted { get; } TResult GetResult(); } Here the only difference is, GetResult() return a result. Task<TResult>.GetAwaiter() / TaskAwaiter<TResult>.GetResult() is of this case. Please notice .NET does not define these IAwaitable / IAwaiter interfaces at all. As an UI designer, I guess the reason is, IAwaitable interface will constraint GetAwaiter() to be instance method. Actually C# supports both GetAwaiter() instance method and GetAwaiter() extension method. Here I use these interfaces only for better visualizing what is awaitable / awaiter. Now, if looking at above ConfiguredTaskAwaitable / ConfiguredTaskAwaiter, YieldAwaitable / YieldAwaiter, Task / TaskAwaiter pairs again, they all “implicitly” implement these “missing” IAwaitable / IAwaiter interfaces. In the next part, we will see how to implement awaitable / awaiter. Await any function / action In C# await cannot be used with lambda. This code: int result = await (() => 0); will cause a compiler error: Cannot await 'lambda expression' This is easy to understand because this lambda expression (() => 0) may be a function or a expression tree. Obviously we mean function here, and we can tell compiler in this way: int result = await new Func<int>(() => 0); It causes an different error: Cannot await 'System.Func<int>' OK, now the compiler is complaining the type instead of syntax. With the understanding of the awaitable / awaiter pattern, Func<TResult> type can be easily made into awaitable. GetAwaiter() instance method, using IAwaitable / IAwaiter interfaces First, similar to above ConfiguredTaskAwaitable<TResult>, a FuncAwaitable<TResult> can be implemented to wrap Func<TResult>: internal struct FuncAwaitable<TResult> : IAwaitable<TResult> { private readonly Func<TResult> function; public FuncAwaitable(Func<TResult> function) { this.function = function; } public IAwaiter<TResult> GetAwaiter() { return new FuncAwaiter<TResult>(this.function); } } FuncAwaitable<TResult> wrapper is used to implement IAwaitable<TResult>, so it has one instance method, GetAwaiter(), which returns a IAwaiter<TResult>, which wraps that Func<TResult> too. FuncAwaiter<TResult> is used to implement IAwaiter<TResult>: public struct FuncAwaiter<TResult> : IAwaiter<TResult> { private readonly Task<TResult> task; public FuncAwaiter(Func<TResult> function) { this.task = new Task<TResult>(function); this.task.Start(); } bool IAwaiter<TResult>.IsCompleted { get { return this.task.IsCompleted; } } TResult IAwaiter<TResult>.GetResult() { return this.task.Result; } void INotifyCompletion.OnCompleted(Action continuation) { new Task(continuation).Start(); } } Now a function can be awaited in this way: int result = await new FuncAwaitable<int>(() => 0); GetAwaiter() extension method As IAwaitable shows, all that an awaitable needs is just a GetAwaiter() method. In above code, FuncAwaitable<TResult> is created as a wrapper of Func<TResult> and implements IAwaitable<TResult>, so that there is a GetAwaiter() instance method. If a GetAwaiter() extension method can be defined for Func<TResult>, then FuncAwaitable<TResult> is no longer needed: public static class FuncExtensions { public static IAwaiter<TResult> GetAwaiter<TResult>(this Func<TResult> function) { return new FuncAwaiter<TResult>(function); } } So a Func<TResult> function can be directly awaited: int result = await new Func<int>(() => 0); Using the existing awaitable / awaiter - Task / TaskAwaiter Remember the most frequently used awaitable / awaiter - Task / TaskAwaiter. With Task / TaskAwaiter, FuncAwaitable / FuncAwaiter are no longer needed: public static class FuncExtensions { public static TaskAwaiter<TResult> GetAwaiter<TResult>(this Func<TResult> function) { Task<TResult> task = new Task<TResult>(function); task.Start(); return task.GetAwaiter(); // Returns a TaskAwaiter<TResult>. } } Similarly, with this extension method: public static class ActionExtensions { public static TaskAwaiter GetAwaiter(this Action action) { Task task = new Task(action); task.Start(); return task.GetAwaiter(); // Returns a TaskAwaiter. } } an action can be awaited as well: await new Action(() => { }); Now any function / action can be awaited: await new Action(() => HelperMethods.IO()); // or: await new Action(HelperMethods.IO); If function / action has parameter(s), closure can be used: int arg0 = 0; int arg1 = 1; int result = await new Action(() => HelperMethods.IO(arg0, arg1)); Using Task.Run() The above code is used to demonstrate how awaitable / awaiter can be implemented. Because it is a common scenario to await a function / action, so .NET provides a built-in API: Task.Run(): public class Task2 { public static Task Run(Action action) { // The implementation is similar to: Task task = new Task(action); task.Start(); return task; } public static Task<TResult> Run<TResult>(Func<TResult> function) { // The implementation is similar to: Task<TResult> task = new Task<TResult>(function); task.Start(); return task; } } In reality, this is how we await a function: int result = await Task.Run(() => HelperMethods.IO(arg0, arg1)); and await a action: await Task.Run(() => HelperMethods.IO());

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Understanding C# async / await (1) Compilation

- by Dixin

Now the async / await keywords are in C#. Just like the async and ! in F#, this new C# feature provides great convenience. There are many nice documents talking about how to use async / await in specific scenarios, like using async methods in ASP.NET 4.5 and in ASP.NET MVC 4, etc. In this article we will look at the real code working behind the syntax sugar. According to MSDN: The async modifier indicates that the method, lambda expression, or anonymous method that it modifies is asynchronous. Since lambda expression / anonymous method will be compiled to normal method, we will focus on normal async method. Preparation First of all, Some helper methods need to make up. internal class HelperMethods { internal static int Method(int arg0, int arg1) { // Do some IO. WebClient client = new WebClient(); Enumerable.Repeat("http://weblogs.asp.net/dixin", 10) .Select(client.DownloadString).ToArray(); int result = arg0 + arg1; return result; } internal static Task<int> MethodTask(int arg0, int arg1) { Task<int> task = new Task<int>(() => Method(arg0, arg1)); task.Start(); // Hot task (started task) should always be returned. return task; } internal static void Before() { } internal static void Continuation1(int arg) { } internal static void Continuation2(int arg) { } } Here Method() is a long running method doing some IO. Then MethodTask() wraps it into a Task and return that Task. Nothing special here. Await something in async method Since MethodTask() returns Task, let’s try to await it: internal class AsyncMethods { internal static async Task<int> MethodAsync(int arg0, int arg1) { int result = await HelperMethods.MethodTask(arg0, arg1); return result; } } Because we used await in the method, async must be put on the method. Now we get the first async method. According to the naming convenience, it is called MethodAsync. Of course a async method can be awaited. So we have a CallMethodAsync() to call MethodAsync(): internal class AsyncMethods { internal static async Task<int> CallMethodAsync(int arg0, int arg1) { int result = await MethodAsync(arg0, arg1); return result; } } After compilation, MethodAsync() and CallMethodAsync() becomes the same logic. This is the code of MethodAsyc(): internal class CompiledAsyncMethods { [DebuggerStepThrough] [AsyncStateMachine(typeof(MethodAsyncStateMachine))] // async internal static /*async*/ Task<int> MethodAsync(int arg0, int arg1) { MethodAsyncStateMachine methodAsyncStateMachine = new MethodAsyncStateMachine() { Arg0 = arg0, Arg1 = arg1, Builder = AsyncTaskMethodBuilder<int>.Create(), State = -1 }; methodAsyncStateMachine.Builder.Start(ref methodAsyncStateMachine); return methodAsyncStateMachine.Builder.Task; } } It just creates and starts a state machine MethodAsyncStateMachine: [CompilerGenerated] [StructLayout(LayoutKind.Auto)] internal struct MethodAsyncStateMachine : IAsyncStateMachine { public int State; public AsyncTaskMethodBuilder<int> Builder; public int Arg0; public int Arg1; public int Result; private TaskAwaiter<int> awaitor; void IAsyncStateMachine.MoveNext() { try { if (this.State != 0) { this.awaitor = HelperMethods.MethodTask(this.Arg0, this.Arg1).GetAwaiter(); if (!this.awaitor.IsCompleted) { this.State = 0; this.Builder.AwaitUnsafeOnCompleted(ref this.awaitor, ref this); return; } } else { this.State = -1; } this.Result = this.awaitor.GetResult(); } catch (Exception exception) { this.State = -2; this.Builder.SetException(exception); return; } this.State = -2; this.Builder.SetResult(this.Result); } [DebuggerHidden] void IAsyncStateMachine.SetStateMachine(IAsyncStateMachine param0) { this.Builder.SetStateMachine(param0); } } The generated code has been cleaned up so it is readable and can be compiled. Several things can be observed here: The async modifier is gone, which shows, unlike other modifiers (e.g. static), there is no such IL/CLR level “async” stuff. It becomes a AsyncStateMachineAttribute. This is similar to the compilation of extension method. The generated state machine is very similar to the state machine of C# yield syntax sugar. The local variables (arg0, arg1, result) are compiled to fields of the state machine. The real code (await HelperMethods.MethodTask(arg0, arg1)) is compiled into MoveNext(): HelperMethods.MethodTask(this.Arg0, this.Arg1).GetAwaiter(). CallMethodAsync() will create and start its own state machine CallMethodAsyncStateMachine: internal class CompiledAsyncMethods { [DebuggerStepThrough] [AsyncStateMachine(typeof(CallMethodAsyncStateMachine))] // async internal static /*async*/ Task<int> CallMethodAsync(int arg0, int arg1) { CallMethodAsyncStateMachine callMethodAsyncStateMachine = new CallMethodAsyncStateMachine() { Arg0 = arg0, Arg1 = arg1, Builder = AsyncTaskMethodBuilder<int>.Create(), State = -1 }; callMethodAsyncStateMachine.Builder.Start(ref callMethodAsyncStateMachine); return callMethodAsyncStateMachine.Builder.Task; } } CallMethodAsyncStateMachine has the same logic as MethodAsyncStateMachine above. The detail of the state machine will be discussed soon. Now it is clear that: async /await is a C# level syntax sugar. There is no difference to await a async method or a normal method. A method returning Task will be awaitable. State machine and continuation To demonstrate more details in the state machine, a more complex method is created: internal class AsyncMethods { internal static async Task<int> MultiCallMethodAsync(int arg0, int arg1, int arg2, int arg3) { HelperMethods.Before(); int resultOfAwait1 = await MethodAsync(arg0, arg1); HelperMethods.Continuation1(resultOfAwait1); int resultOfAwait2 = await MethodAsync(arg2, arg3); HelperMethods.Continuation2(resultOfAwait2); int resultToReturn = resultOfAwait1 + resultOfAwait2; return resultToReturn; } } In this method: There are multiple awaits. There are code before the awaits, and continuation code after each await After compilation, this multi-await method becomes the same as above single-await methods: internal class CompiledAsyncMethods { [DebuggerStepThrough] [AsyncStateMachine(typeof(MultiCallMethodAsyncStateMachine))] // async internal static /*async*/ Task<int> MultiCallMethodAsync(int arg0, int arg1, int arg2, int arg3) { MultiCallMethodAsyncStateMachine multiCallMethodAsyncStateMachine = new MultiCallMethodAsyncStateMachine() { Arg0 = arg0, Arg1 = arg1, Arg2 = arg2, Arg3 = arg3, Builder = AsyncTaskMethodBuilder<int>.Create(), State = -1 }; multiCallMethodAsyncStateMachine.Builder.Start(ref multiCallMethodAsyncStateMachine); return multiCallMethodAsyncStateMachine.Builder.Task; } } It creates and starts one single state machine, MultiCallMethodAsyncStateMachine: [CompilerGenerated] [StructLayout(LayoutKind.Auto)] internal struct MultiCallMethodAsyncStateMachine : IAsyncStateMachine { public int State; public AsyncTaskMethodBuilder<int> Builder; public int Arg0; public int Arg1; public int Arg2; public int Arg3; public int ResultOfAwait1; public int ResultOfAwait2; public int ResultToReturn; private TaskAwaiter<int> awaiter; void IAsyncStateMachine.MoveNext() { try { switch (this.State) { case -1: HelperMethods.Before(); this.awaiter = AsyncMethods.MethodAsync(this.Arg0, this.Arg1).GetAwaiter(); if (!this.awaiter.IsCompleted) { this.State = 0; this.Builder.AwaitUnsafeOnCompleted(ref this.awaiter, ref this); } break; case 0: this.ResultOfAwait1 = this.awaiter.GetResult(); HelperMethods.Continuation1(this.ResultOfAwait1); this.awaiter = AsyncMethods.MethodAsync(this.Arg2, this.Arg3).GetAwaiter(); if (!this.awaiter.IsCompleted) { this.State = 1; this.Builder.AwaitUnsafeOnCompleted(ref this.awaiter, ref this); } break; case 1: this.ResultOfAwait2 = this.awaiter.GetResult(); HelperMethods.Continuation2(this.ResultOfAwait2); this.ResultToReturn = this.ResultOfAwait1 + this.ResultOfAwait2; this.State = -2; this.Builder.SetResult(this.ResultToReturn); break; } } catch (Exception exception) { this.State = -2; this.Builder.SetException(exception); } } [DebuggerHidden] void IAsyncStateMachine.SetStateMachine(IAsyncStateMachine stateMachine) { this.Builder.SetStateMachine(stateMachine); } } The above code is already cleaned up, but there are still a lot of things. More clean up can be done, and the state machine can be very simple: [CompilerGenerated] [StructLayout(LayoutKind.Auto)] internal struct MultiCallMethodAsyncStateMachine : IAsyncStateMachine { // State: // -1: Begin // 0: 1st await is done // 1: 2nd await is done // ... // -2: End public int State; public TaskCompletionSource<int> ResultToReturn; // int resultToReturn ... public int Arg0; // int Arg0 public int Arg1; // int arg1 public int Arg2; // int arg2 public int Arg3; // int arg3 public int ResultOfAwait1; // int resultOfAwait1 ... public int ResultOfAwait2; // int resultOfAwait2 ... private Task<int> currentTaskToAwait; /// <summary> /// Moves the state machine to its next state. /// </summary> void IAsyncStateMachine.MoveNext() { try { switch (this.State) { // Orginal code is splitted by "case"s: // case -1: // HelperMethods.Before(); // MethodAsync(Arg0, arg1); // case 0: // int resultOfAwait1 = await ... // HelperMethods.Continuation1(resultOfAwait1); // MethodAsync(arg2, arg3); // case 1: // int resultOfAwait2 = await ... // HelperMethods.Continuation2(resultOfAwait2); // int resultToReturn = resultOfAwait1 + resultOfAwait2; // return resultToReturn; case -1: // -1 is begin. HelperMethods.Before(); // Code before 1st await. this.currentTaskToAwait = AsyncMethods.MethodAsync(this.Arg0, this.Arg1); // 1st task to await // When this.currentTaskToAwait is done, run this.MoveNext() and go to case 0. this.State = 0; IAsyncStateMachine this1 = this; // Cannot use "this" in lambda so create a local variable. this.currentTaskToAwait.ContinueWith(_ => this1.MoveNext()); // Callback break; case 0: // Now 1st await is done. this.ResultOfAwait1 = this.currentTaskToAwait.Result; // Get 1st await's result. HelperMethods.Continuation1(this.ResultOfAwait1); // Code after 1st await and before 2nd await. this.currentTaskToAwait = AsyncMethods.MethodAsync(this.Arg2, this.Arg3); // 2nd task to await // When this.currentTaskToAwait is done, run this.MoveNext() and go to case 1. this.State = 1; IAsyncStateMachine this2 = this; // Cannot use "this" in lambda so create a local variable. this.currentTaskToAwait.ContinueWith(_ => this2.MoveNext()); // Callback break; case 1: // Now 2nd await is done. this.ResultOfAwait2 = this.currentTaskToAwait.Result; // Get 2nd await's result. HelperMethods.Continuation2(this.ResultOfAwait2); // Code after 2nd await. int resultToReturn = this.ResultOfAwait1 + this.ResultOfAwait2; // Code after 2nd await. // End with resultToReturn. this.State = -2; // -2 is end. this.ResultToReturn.SetResult(resultToReturn); break; } } catch (Exception exception) { // End with exception. this.State = -2; // -2 is end. this.ResultToReturn.SetException(exception); } } /// <summary> /// Configures the state machine with a heap-allocated replica. /// </summary> /// <param name="stateMachine">The heap-allocated replica.</param> [DebuggerHidden] void IAsyncStateMachine.SetStateMachine(IAsyncStateMachine stateMachine) { // No core logic. } } Only Task and TaskCompletionSource are involved in this version. And MultiCallMethodAsync() can be simplified to: [DebuggerStepThrough] [AsyncStateMachine(typeof(MultiCallMethodAsyncStateMachine))] // async internal static /*async*/ Task<int> MultiCallMethodAsync_(int arg0, int arg1, int arg2, int arg3) { MultiCallMethodAsyncStateMachine multiCallMethodAsyncStateMachine = new MultiCallMethodAsyncStateMachine() { Arg0 = arg0, Arg1 = arg1, Arg2 = arg2, Arg3 = arg3, ResultToReturn = new TaskCompletionSource<int>(), // -1: Begin // 0: 1st await is done // 1: 2nd await is done // ... // -2: End State = -1 }; (multiCallMethodAsyncStateMachine as IAsyncStateMachine).MoveNext(); // Original code are in this method. return multiCallMethodAsyncStateMachine.ResultToReturn.Task; } Now the whole state machine becomes very clear - it is about callback: Original code are split into pieces by “await”s, and each piece is put into each “case” in the state machine. Here the 2 awaits split the code into 3 pieces, so there are 3 “case”s. The “piece”s are chained by callback, that is done by Builder.AwaitUnsafeOnCompleted(callback), or currentTaskToAwait.ContinueWith(callback) in the simplified code. A previous “piece” will end with a Task (which is to be awaited), when the task is done, it will callback the next “piece”. The state machine’s state works with the “case”s to ensure the code “piece”s executes one after another. Callback Since it is about callback, the simplification can go even further – the entire state machine can be completely purged. Now MultiCallMethodAsync() becomes: internal static Task<int> MultiCallMethodAsync(int arg0, int arg1, int arg2, int arg3) { TaskCompletionSource<int> taskCompletionSource = new TaskCompletionSource<int>(); try { // Oringinal code begins. HelperMethods.Before(); MethodAsync(arg0, arg1).ContinueWith(await1 => { int resultOfAwait1 = await1.Result; HelperMethods.Continuation1(resultOfAwait1); MethodAsync(arg2, arg3).ContinueWith(await2 => { int resultOfAwait2 = await2.Result; HelperMethods.Continuation2(resultOfAwait2); int resultToReturn = resultOfAwait1 + resultOfAwait2; // Oringinal code ends. taskCompletionSource.SetResult(resultToReturn); }); }); } catch (Exception exception) { taskCompletionSource.SetException(exception); } return taskCompletionSource.Task; } Please compare with the original async / await code: HelperMethods.Before(); int resultOfAwait1 = await MethodAsync(arg0, arg1); HelperMethods.Continuation1(resultOfAwait1); int resultOfAwait2 = await MethodAsync(arg2, arg3); HelperMethods.Continuation2(resultOfAwait2); int resultToReturn = resultOfAwait1 + resultOfAwait2; return resultToReturn; Yeah that is the magic of C# async / await: Await is literally pretending to wait. In a await expression, a Task object will be return immediately so that caller is not blocked. The continuation code is compiled as that Task’s callback code. When that task is done, continuation code will execute. Please notice that many details inside the state machine are omitted for simplicity, like context caring, etc. If you want to have a detailed picture, please do check out the source code of AsyncTaskMethodBuilder and TaskAwaiter.

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Understanding C# async / await (1) Compilation

- by Dixin

Now the async / await keywords are in C#. Just like the async and ! in F#, this new C# feature provides great convenience. There are many nice documents talking about how to use async / await in specific scenarios, like using async methods in ASP.NET 4.5 and in ASP.NET MVC 4, etc. In this article we will look at the real code working behind the syntax sugar. According to MSDN: The async modifier indicates that the method, lambda expression, or anonymous method that it modifies is asynchronous. Since lambda expression / anonymous method will be compiled to normal method, we will focus on normal async method. Preparation First of all, Some helper methods need to make up. internal class HelperMethods { internal static int Method(int arg0, int arg1) { // Do some IO. WebClient client = new WebClient(); Enumerable.Repeat("http://weblogs.asp.net/dixin", 10) .Select(client.DownloadString).ToArray(); int result = arg0 + arg1; return result; } internal static Task<int> MethodTask(int arg0, int arg1) { Task<int> task = new Task<int>(() => Method(arg0, arg1)); task.Start(); // Hot task (started task) should always be returned. return task; } internal static void Before() { } internal static void Continuation1(int arg) { } internal static void Continuation2(int arg) { } } Here Method() is a long running method doing some IO. Then MethodTask() wraps it into a Task and return that Task. Nothing special here. Await something in async method Since MethodTask() returns Task, let’s try to await it: internal class AsyncMethods { internal static async Task<int> MethodAsync(int arg0, int arg1) { int result = await HelperMethods.MethodTask(arg0, arg1); return result; } } Because we used await in the method, async must be put on the method. Now we get the first async method. According to the naming convenience, it is named MethodAsync. Of course a async method can be awaited. So we have a CallMethodAsync() to call MethodAsync(): internal class AsyncMethods { internal static async Task<int> CallMethodAsync(int arg0, int arg1) { int result = await MethodAsync(arg0, arg1); return result; } } After compilation, MethodAsync() and CallMethodAsync() becomes the same logic. This is the code of MethodAsyc(): internal class CompiledAsyncMethods { [DebuggerStepThrough] [AsyncStateMachine(typeof(MethodAsyncStateMachine))] // async internal static /*async*/ Task<int> MethodAsync(int arg0, int arg1) { MethodAsyncStateMachine methodAsyncStateMachine = new MethodAsyncStateMachine() { Arg0 = arg0, Arg1 = arg1, Builder = AsyncTaskMethodBuilder<int>.Create(), State = -1 }; methodAsyncStateMachine.Builder.Start(ref methodAsyncStateMachine); return methodAsyncStateMachine.Builder.Task; } } It just creates and starts a state machine, MethodAsyncStateMachine: [CompilerGenerated] [StructLayout(LayoutKind.Auto)] internal struct MethodAsyncStateMachine : IAsyncStateMachine { public int State; public AsyncTaskMethodBuilder<int> Builder; public int Arg0; public int Arg1; public int Result; private TaskAwaiter<int> awaitor; void IAsyncStateMachine.MoveNext() { try { if (this.State != 0) { this.awaitor = HelperMethods.MethodTask(this.Arg0, this.Arg1).GetAwaiter(); if (!this.awaitor.IsCompleted) { this.State = 0; this.Builder.AwaitUnsafeOnCompleted(ref this.awaitor, ref this); return; } } else { this.State = -1; } this.Result = this.awaitor.GetResult(); } catch (Exception exception) { this.State = -2; this.Builder.SetException(exception); return; } this.State = -2; this.Builder.SetResult(this.Result); } [DebuggerHidden] void IAsyncStateMachine.SetStateMachine(IAsyncStateMachine param0) { this.Builder.SetStateMachine(param0); } } The generated code has been refactored, so it is readable and can be compiled. Several things can be observed here: The async modifier is gone, which shows, unlike other modifiers (e.g. static), there is no such IL/CLR level “async” stuff. It becomes a AsyncStateMachineAttribute. This is similar to the compilation of extension method. The generated state machine is very similar to the state machine of C# yield syntax sugar. The local variables (arg0, arg1, result) are compiled to fields of the state machine. The real code (await HelperMethods.MethodTask(arg0, arg1)) is compiled into MoveNext(): HelperMethods.MethodTask(this.Arg0, this.Arg1).GetAwaiter(). CallMethodAsync() will create and start its own state machine CallMethodAsyncStateMachine: internal class CompiledAsyncMethods { [DebuggerStepThrough] [AsyncStateMachine(typeof(CallMethodAsyncStateMachine))] // async internal static /*async*/ Task<int> CallMethodAsync(int arg0, int arg1) { CallMethodAsyncStateMachine callMethodAsyncStateMachine = new CallMethodAsyncStateMachine() { Arg0 = arg0, Arg1 = arg1, Builder = AsyncTaskMethodBuilder<int>.Create(), State = -1 }; callMethodAsyncStateMachine.Builder.Start(ref callMethodAsyncStateMachine); return callMethodAsyncStateMachine.Builder.Task; } } CallMethodAsyncStateMachine has the same logic as MethodAsyncStateMachine above. The detail of the state machine will be discussed soon. Now it is clear that: async /await is a C# language level syntax sugar. There is no difference to await a async method or a normal method. As long as a method returns Task, it is awaitable. State machine and continuation To demonstrate more details in the state machine, a more complex method is created: internal class AsyncMethods { internal static async Task<int> MultiCallMethodAsync(int arg0, int arg1, int arg2, int arg3) { HelperMethods.Before(); int resultOfAwait1 = await MethodAsync(arg0, arg1); HelperMethods.Continuation1(resultOfAwait1); int resultOfAwait2 = await MethodAsync(arg2, arg3); HelperMethods.Continuation2(resultOfAwait2); int resultToReturn = resultOfAwait1 + resultOfAwait2; return resultToReturn; } } In this method: There are multiple awaits. There are code before the awaits, and continuation code after each await After compilation, this multi-await method becomes the same as above single-await methods: internal class CompiledAsyncMethods { [DebuggerStepThrough] [AsyncStateMachine(typeof(MultiCallMethodAsyncStateMachine))] // async internal static /*async*/ Task<int> MultiCallMethodAsync(int arg0, int arg1, int arg2, int arg3) { MultiCallMethodAsyncStateMachine multiCallMethodAsyncStateMachine = new MultiCallMethodAsyncStateMachine() { Arg0 = arg0, Arg1 = arg1, Arg2 = arg2, Arg3 = arg3, Builder = AsyncTaskMethodBuilder<int>.Create(), State = -1 }; multiCallMethodAsyncStateMachine.Builder.Start(ref multiCallMethodAsyncStateMachine); return multiCallMethodAsyncStateMachine.Builder.Task; } } It creates and starts one single state machine, MultiCallMethodAsyncStateMachine: [CompilerGenerated] [StructLayout(LayoutKind.Auto)] internal struct MultiCallMethodAsyncStateMachine : IAsyncStateMachine { public int State; public AsyncTaskMethodBuilder<int> Builder; public int Arg0; public int Arg1; public int Arg2; public int Arg3; public int ResultOfAwait1; public int ResultOfAwait2; public int ResultToReturn; private TaskAwaiter<int> awaiter; void IAsyncStateMachine.MoveNext() { try { switch (this.State) { case -1: HelperMethods.Before(); this.awaiter = AsyncMethods.MethodAsync(this.Arg0, this.Arg1).GetAwaiter(); if (!this.awaiter.IsCompleted) { this.State = 0; this.Builder.AwaitUnsafeOnCompleted(ref this.awaiter, ref this); } break; case 0: this.ResultOfAwait1 = this.awaiter.GetResult(); HelperMethods.Continuation1(this.ResultOfAwait1); this.awaiter = AsyncMethods.MethodAsync(this.Arg2, this.Arg3).GetAwaiter(); if (!this.awaiter.IsCompleted) { this.State = 1; this.Builder.AwaitUnsafeOnCompleted(ref this.awaiter, ref this); } break; case 1: this.ResultOfAwait2 = this.awaiter.GetResult(); HelperMethods.Continuation2(this.ResultOfAwait2); this.ResultToReturn = this.ResultOfAwait1 + this.ResultOfAwait2; this.State = -2; this.Builder.SetResult(this.ResultToReturn); break; } } catch (Exception exception) { this.State = -2; this.Builder.SetException(exception); } } [DebuggerHidden] void IAsyncStateMachine.SetStateMachine(IAsyncStateMachine stateMachine) { this.Builder.SetStateMachine(stateMachine); } } Once again, the above state machine code is already refactored, but it still has a lot of things. More clean up can be done if we only keep the core logic, and the state machine can become very simple: [CompilerGenerated] [StructLayout(LayoutKind.Auto)] internal struct MultiCallMethodAsyncStateMachine : IAsyncStateMachine { // State: // -1: Begin // 0: 1st await is done // 1: 2nd await is done // ... // -2: End public int State; public TaskCompletionSource<int> ResultToReturn; // int resultToReturn ... public int Arg0; // int Arg0 public int Arg1; // int arg1 public int Arg2; // int arg2 public int Arg3; // int arg3 public int ResultOfAwait1; // int resultOfAwait1 ... public int ResultOfAwait2; // int resultOfAwait2 ... private Task<int> currentTaskToAwait; /// <summary> /// Moves the state machine to its next state. /// </summary> public void MoveNext() // IAsyncStateMachine member. { try { switch (this.State) { // Original code is split by "await"s into "case"s: // case -1: // HelperMethods.Before(); // MethodAsync(Arg0, arg1); // case 0: // int resultOfAwait1 = await ... // HelperMethods.Continuation1(resultOfAwait1); // MethodAsync(arg2, arg3); // case 1: // int resultOfAwait2 = await ... // HelperMethods.Continuation2(resultOfAwait2); // int resultToReturn = resultOfAwait1 + resultOfAwait2; // return resultToReturn; case -1: // -1 is begin. HelperMethods.Before(); // Code before 1st await. this.currentTaskToAwait = AsyncMethods.MethodAsync(this.Arg0, this.Arg1); // 1st task to await // When this.currentTaskToAwait is done, run this.MoveNext() and go to case 0. this.State = 0; MultiCallMethodAsyncStateMachine that1 = this; // Cannot use "this" in lambda so create a local variable. this.currentTaskToAwait.ContinueWith(_ => that1.MoveNext()); break; case 0: // Now 1st await is done. this.ResultOfAwait1 = this.currentTaskToAwait.Result; // Get 1st await's result. HelperMethods.Continuation1(this.ResultOfAwait1); // Code after 1st await and before 2nd await. this.currentTaskToAwait = AsyncMethods.MethodAsync(this.Arg2, this.Arg3); // 2nd task to await // When this.currentTaskToAwait is done, run this.MoveNext() and go to case 1. this.State = 1; MultiCallMethodAsyncStateMachine that2 = this; this.currentTaskToAwait.ContinueWith(_ => that2.MoveNext()); break; case 1: // Now 2nd await is done. this.ResultOfAwait2 = this.currentTaskToAwait.Result; // Get 2nd await's result. HelperMethods.Continuation2(this.ResultOfAwait2); // Code after 2nd await. int resultToReturn = this.ResultOfAwait1 + this.ResultOfAwait2; // Code after 2nd await. // End with resultToReturn. this.State = -2; // -2 is end. this.ResultToReturn.SetResult(resultToReturn); break; } } catch (Exception exception) { // End with exception. this.State = -2; // -2 is end. this.ResultToReturn.SetException(exception); } } /// <summary> /// Configures the state machine with a heap-allocated replica. /// </summary> /// <param name="stateMachine">The heap-allocated replica.</param> [DebuggerHidden] public void SetStateMachine(IAsyncStateMachine stateMachine) // IAsyncStateMachine member. { // No core logic. } } Only Task and TaskCompletionSource are involved in this version. And MultiCallMethodAsync() can be simplified to: [DebuggerStepThrough] [AsyncStateMachine(typeof(MultiCallMethodAsyncStateMachine))] // async internal static /*async*/ Task<int> MultiCallMethodAsync(int arg0, int arg1, int arg2, int arg3) { MultiCallMethodAsyncStateMachine multiCallMethodAsyncStateMachine = new MultiCallMethodAsyncStateMachine() { Arg0 = arg0, Arg1 = arg1, Arg2 = arg2, Arg3 = arg3, ResultToReturn = new TaskCompletionSource<int>(), // -1: Begin // 0: 1st await is done // 1: 2nd await is done // ... // -2: End State = -1 }; multiCallMethodAsyncStateMachine.MoveNext(); // Original code are moved into this method. return multiCallMethodAsyncStateMachine.ResultToReturn.Task; } Now the whole state machine becomes very clean - it is about callback: Original code are split into pieces by “await”s, and each piece is put into each “case” in the state machine. Here the 2 awaits split the code into 3 pieces, so there are 3 “case”s. The “piece”s are chained by callback, that is done by Builder.AwaitUnsafeOnCompleted(callback), or currentTaskToAwait.ContinueWith(callback) in the simplified code. A previous “piece” will end with a Task (which is to be awaited), when the task is done, it will callback the next “piece”. The state machine’s state works with the “case”s to ensure the code “piece”s executes one after another. Callback If we focus on the point of callback, the simplification can go even further – the entire state machine can be completely purged, and we can just keep the code inside MoveNext(). Now MultiCallMethodAsync() becomes: internal static Task<int> MultiCallMethodAsync(int arg0, int arg1, int arg2, int arg3) { TaskCompletionSource<int> taskCompletionSource = new TaskCompletionSource<int>(); try { // Oringinal code begins. HelperMethods.Before(); MethodAsync(arg0, arg1).ContinueWith(await1 => { int resultOfAwait1 = await1.Result; HelperMethods.Continuation1(resultOfAwait1); MethodAsync(arg2, arg3).ContinueWith(await2 => { int resultOfAwait2 = await2.Result; HelperMethods.Continuation2(resultOfAwait2); int resultToReturn = resultOfAwait1 + resultOfAwait2; // Oringinal code ends. taskCompletionSource.SetResult(resultToReturn); }); }); } catch (Exception exception) { taskCompletionSource.SetException(exception); } return taskCompletionSource.Task; } Please compare with the original async / await code: HelperMethods.Before(); int resultOfAwait1 = await MethodAsync(arg0, arg1); HelperMethods.Continuation1(resultOfAwait1); int resultOfAwait2 = await MethodAsync(arg2, arg3); HelperMethods.Continuation2(resultOfAwait2); int resultToReturn = resultOfAwait1 + resultOfAwait2; return resultToReturn; Yeah that is the magic of C# async / await: Await is not to wait. In a await expression, a Task object will be return immediately so that execution is not blocked. The continuation code is compiled as that Task’s callback code. When that task is done, continuation code will execute. Please notice that many details inside the state machine are omitted for simplicity, like context caring, etc. If you want to have a detailed picture, please do check out the source code of AsyncTaskMethodBuilder and TaskAwaiter.

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