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  • Is it safe to take the address of std::wstring's internal pointer?

    - by LCC
    I have an interface which is used like the following: if (SUCCEEDED(pInterface->GetSize(&size)) { wchar_t tmp = new wchar_t[size]; if (SUCCEEDED(pInterface->GetValue(tmp, size))) { std::wstring str = tmp; // do some work which doesn't throw } delete[] tmp; } Is it safe and portable to do this instead? if (SUCCEEDED(pInterface->GetSize(&size)) { std::wstring str; str.resize(size); if (SUCCEEDED(pInterface->GetValue(&str[0], size))) { // do some work } } Now, obviously this works (doesn't crash/corrupt memory) or I wouldn't have asked, but I'm mostly wanting to know if there's a compelling reason not to do this.

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  • Why are there two implementations of std::sort (with and without a comparator) rather than one implementation with a default template parameter?

    - by PolyVox
    In my code I'm adopting a design strategy which is similar to some standard library algorithms in that the exact behavior can be customized by a function object. The simplest example is std::sort, where a function object can control how the comparison is made between objects. I notice that the Visual C++ provides two implementations of std::sort, which naturally involves code duplication. I would have imagined that it was instead possible to have only one implementation, and provide a default comparator (using operator< ) as a default template parameter. What is the rational behind two separate versions? Would my suggestion make the interface more complex in some way? Or result in confusing error messages when the object does not provide operator Thanks, David

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  • including a std::map within a struct? Is it ok?

    - by user553514
    class X_class{ public: struct extra {int extra1; int extra2; int extra3; }; enum a { n,m}; struct x_struct{ char b; char c; int d; int e; std::map <int, extra> myExtraMap; }; }; in my code I define : x_struct myStruct; why do I get compile errors compiling the above class? The error either says: 1) expected ; before < on the line --- where I defined the map (above) if I eliminate std:: or 2) error: invalid use of ::; error: expected ; before < token

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  • Win 2003 STD network adapter always showing DHCP when in static IP configuration, + it loses the DNS

    - by Darragh
    Hi, I have a server that after the first configuration it was DHCP, now I have added it to our domain and in a static IP, however after a few moments it returns to DHCP but with only some of the IPv4 setting staying the same, It loses DNS for example. I'm not sure what is causing the problem but all I know is this started to happen after I added it to the domain, Would it be a domain policy? or the NIC drivers Spec; Dell M605 Blade server Windows 2003 STD SP1 Intel Xeon Quad core NIC: Dual embedded Broadcom NetXtreme IITM 5708 Gigabit Ethernet NIC w/ TOE

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  • Bewildering SegFault involving STL sort algorithm.

    - by just_wes
    Hello everybody, I am completely perplexed at a seg fault that I seem to be creating. I have: vector<unsigned int> words; and global variable string input; I define my custom compare function: bool wordncompare(unsigned int f, unsigned int s) { int n = k; while (((f < input.size()) && (s < input.size())) && (input[f] == input[s])) { if ((input[f] == ' ') && (--n == 0)) { return false; } f++; s++; } return true; } When I run the code: sort(words.begin(), words.end()); The program exits smoothly. However, when I run the code: sort(words.begin(), words.end(), wordncompare); I generate a SegFault deep within the STL. The GDB back-trace code looks like this: #0 0x00007ffff7b79893 in std::string::size() const () from /usr/lib/gcc/x86_64-pc-linux-gnu/4.3.4/libstdc++.so.6 #1 0x0000000000400f3f in wordncompare (f=90, s=0) at text_gen2.cpp:40 #2 0x000000000040188d in std::__unguarded_linear_insert<__gnu_cxx::__normal_iterator<unsigned int*, std::vector<unsigned int, std::allocator<unsigned int> > >, unsigned int, bool (*)(unsigned int, unsigned int)> (__last=..., __val=90, __comp=0x400edc <wordncompare(unsigned int, unsigned int)>) at /usr/lib/gcc/x86_64-pc-linux-gnu/4.3.4/include/g++-v4/bits/stl_algo.h:1735 #3 0x00000000004018df in std::__unguarded_insertion_sort<__gnu_cxx::__normal_iterator<unsigned int*, std::vector<unsigned int, std::allocator<unsigned int> > >, bool (*)(unsigned int, unsigned int)> (__first=..., __last=..., __comp=0x400edc <wordncompare(unsigned int, unsigned int)>) at /usr/lib/gcc/x86_64-pc-linux-gnu/4.3.4/include/g++-v4/bits/stl_algo.h:1812 #4 0x0000000000402562 in std::__final_insertion_sort<__gnu_cxx::__normal_iterator<unsigned int*, std::vector<unsigned int, std::allocator<unsigned int> > >, bool (*)(unsigned int, unsigned int)> (__first=..., __last=..., __comp=0x400edc <wordncompare(unsigned int, unsigned int)>) at /usr/lib/gcc/x86_64-pc-linux-gnu/4.3.4/include/g++-v4/bits/stl_algo.h:1845 #5 0x0000000000402c20 in std::sort<__gnu_cxx::__normal_iterator<unsigned int*, std::vector<unsigned int, std::allocator<unsigned int> > >, bool (*)(unsigned int, unsigned int)> (__first=..., __last=..., __comp=0x400edc <wordncompare(unsigned int, unsigned int)>) at /usr/lib/gcc/x86_64-pc-linux-gnu/4.3.4/include/g++-v4/bits/stl_algo.h:4822 #6 0x00000000004012d2 in main (argc=1, args=0x7fffffffe0b8) at text_gen2.cpp:70 I have similar code in another program, but in that program I am using a vector instead of vector. For the life of me I can't figure out what I'm doing wrong. Thanks!

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  • (static initialization order?!) problems with factory pattern

    - by smerlin
    Why does following code raise an exception (in createObjects call to map::at) alternativly the code (and its output) can be viewed here intererestingly the code works as expected if the commented lines are uncommented with both microsoft and gcc compiler (see here), this even works with initMap as ordinary static variable instead of static getter. The only reason for this i can think of is that the order of initialization of the static registerHelper_ object (factory_helper_)and the std::map object (initMap) are wrong, however i cant see how that could happen, because the map object is constructed on first usage and thats in factory_helper_ constructor, so everything should be alright shouldnt it ? I am even more suprised that those doNothing() lines fix the issue, because that call to doNothing() would happen after the critical section (which currently fails) is passed anyway. EDIT: debugging showed, that without the call to factory_helper_.doNothing(), the constructor of factory_helper_ is never called. #include <iostream> #include <string> #include <map> #define FACTORY_CLASS(classtype) \ extern const char classtype##_name_[] = #classtype; \ class classtype : FactoryBase<classtype,classtype##_name_> namespace detail_ { class registerHelperBase { public: registerHelperBase(){} protected: static std::map<std::string, void * (*)(void)>& getInitMap() { static std::map<std::string, void * (*)(void)>* initMap = 0; if(!initMap) initMap= new std::map<std::string, void * (*)(void)>(); return *initMap; } }; template<class TParent, const char* ClassName> class registerHelper_ : registerHelperBase { static registerHelper_ help_; public: //void doNothing(){} registerHelper_(){ getInitMap()[std::string(ClassName)]=&TParent::factory_init_; } }; template<class TParent, const char* ClassName> registerHelper_<TParent,ClassName> registerHelper_<TParent,ClassName>::help_; } class Factory : detail_::registerHelperBase { private: Factory(); public: static void* createObject(const std::string& objclassname) { return getInitMap().at(objclassname)(); } }; template <class TClass, const char* ClassName> class FactoryBase { private: static detail_::registerHelper_<FactoryBase<TClass,ClassName>,ClassName> factory_helper_; static void* factory_init_(){ return new TClass();} public: friend class detail_::registerHelper_<FactoryBase<TClass,ClassName>,ClassName>; FactoryBase(){ //factory_helper_.doNothing(); } virtual ~FactoryBase(){}; }; template <class TClass, const char* ClassName> detail_::registerHelper_<FactoryBase<TClass,ClassName>,ClassName> FactoryBase<TClass,ClassName>::factory_helper_; FACTORY_CLASS(Test) { public: Test(){} }; int main(int argc, char** argv) { try { Test* test = (Test*) Factory::createObject("Test"); } catch(const std::exception& ex) { std::cerr << "caught std::exception: "<< ex.what() << std::endl; } #ifdef _MSC_VER system("pause"); #endif return 0; }

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  • Improving the efficiency of frustum culling

    - by DeadMG
    I've got some code which performs frustum culling. However, this defines the "frustum" way too broadly- when I have ~10 objects on screen, the code returns 42 objects to be rendered. I've tried taking "slices" through the frustum to attempt to increase the accuracy of the technique, but it doesn't seem to have made much impact. I also significantly reduced the far plane, so that the objects are barely at the edge. Here's my code (where size is the size in screen space- the resolution of the client area of the window I'm rendering into). Any suggestions? auto&& size = GetDimensions(); D3DVIEWPORT9 vp = { 0, 0, size.x, size.y, 0, 1 }; D3DCALL(device->SetViewport(&vp)); static const int slices = 10; std::vector<Object*> result; for(int i = 0; i < slices; i++) { D3DXVECTOR3 WorldSpaceFrustrumPoints[8] = { D3DXVECTOR3(0, size.y, static_cast<float>(i) / slices), D3DXVECTOR3(size.x, 0, static_cast<float>(i) / slices), D3DXVECTOR3(size.x, size.y, static_cast<float>(i) / slices), D3DXVECTOR3(0, 0, static_cast<float>(i) / slices), D3DXVECTOR3(0, 0, static_cast<float>(i + 1) / slices), D3DXVECTOR3(size.x, 0, static_cast<float>(i + 1) / slices), D3DXVECTOR3(size.x, size.y, static_cast<float>(i + 1) / slices), D3DXVECTOR3(0, size.y, static_cast<float>(i + 1) / slices) }; D3DXMATRIXA16 Identity; D3DXMatrixIdentity(&Identity); D3DXVec3UnprojectArray( WorldSpaceFrustrumPoints, sizeof(D3DXVECTOR3), WorldSpaceFrustrumPoints, sizeof(D3DXVECTOR3), &vp, &Projection, &View, &Identity, 8 ); Math::AABB Frustrum; auto world_begin = std::begin(WorldSpaceFrustrumPoints); auto world_end = std::end(WorldSpaceFrustrumPoints); auto world_initial = WorldSpaceFrustrumPoints[0]; Frustrum.BottomLeftClosest.x = std::accumulate(world_begin, world_end, world_initial, [](D3DXVECTOR3 lhs, D3DXVECTOR3 rhs) { return lhs.x < rhs.x ? lhs : rhs; }).x; Frustrum.BottomLeftClosest.y = std::accumulate(world_begin, world_end, world_initial, [](D3DXVECTOR3 lhs, D3DXVECTOR3 rhs) { return lhs.y < rhs.y ? lhs : rhs; }).y; Frustrum.BottomLeftClosest.z = std::accumulate(world_begin, world_end, world_initial, [](D3DXVECTOR3 lhs, D3DXVECTOR3 rhs) { return lhs.z < rhs.z ? lhs : rhs; }).z; Frustrum.TopRightFurthest.x = std::accumulate(world_begin, world_end, world_initial, [](D3DXVECTOR3 lhs, D3DXVECTOR3 rhs) { return lhs.x > rhs.x ? lhs : rhs; }).x; Frustrum.TopRightFurthest.y = std::accumulate(world_begin, world_end, world_initial, [](D3DXVECTOR3 lhs, D3DXVECTOR3 rhs) { return lhs.y > rhs.y ? lhs : rhs; }).y; Frustrum.TopRightFurthest.z = std::accumulate(world_begin, world_end, world_initial, [](D3DXVECTOR3 lhs, D3DXVECTOR3 rhs) { return lhs.z > rhs.z ? lhs : rhs; }).z; auto slices_result = ObjectTree.collision(Frustrum); result.insert(result.end(), slices_result.begin(), slices_result.end()); } return result;

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  • Using array as map value: Cant see the error

    - by Tom
    Hi all, Im trying to create a map, where the key is an int, and the value is an array int red[3] = {1,0,0}; int green[3] = {0,1,0}; int blue[3] = {0,0,1}; std::map<int, int[3]> colours; colours.insert(std::pair<int,int[3]>(GLUT_LEFT_BUTTON,red)); //THIS IS LINE 24 ! colours.insert(std::pair<int,int[3]>(GLUT_MIDDLE_BUTTON,blue)); colours.insert(std::pair<int,int[3]>(GLUT_RIGHT_BUTTON,green)); However, when I try to compile this code, I get the following error. g++ (Ubuntu 4.4.1-4ubuntu8) 4.4.1 In file included from /usr/include/c++/4.4/bits/stl_algobase.h:66, from /usr/include/c++/4.4/bits/stl_tree.h:62, from /usr/include/c++/4.4/map:60, from ../src/utils.cpp:9: /usr/include/c++/4.4/bits/stl_pair.h: In constructor ‘std::pair<_T1, _T2>::pair(const _T1&, const _T2&) [with _T1 = int, _T2 = int [3]]’: ../src/utils.cpp:24: instantiated from here /usr/include/c++/4.4/bits/stl_pair.h:84: error: array used as initializer /usr/include/c++/4.4/bits/stl_pair.h: In constructor ‘std::pair<_T1, _T2>::pair(const std::pair<_U1, _U2>&) [with _U1 = int, _U2 = int [3], _T1 = const int, _T2 = int [3]]’: ../src/utils.cpp:24: instantiated from here /usr/include/c++/4.4/bits/stl_pair.h:101: error: array used as initializer In file included from /usr/include/c++/4.4/map:61, from ../src/utils.cpp:9: /usr/include/c++/4.4/bits/stl_map.h: In member function ‘_Tp& std::map<_Key, _Tp, _Compare, _Alloc>::operator[](const _Key&) [with _Key = int, _Tp = int [3], _Compare = std::less<int>, _Alloc = std::allocator<std::pair<const int, int [3]> >]’: ../src/utils.cpp:30: instantiated from here /usr/include/c++/4.4/bits/stl_map.h:450: error: conversion from ‘int’ to non-scalar type ‘int [3]’ requested make: *** [src/utils.o] Error 1 I really cant see where the error is. Or even if there's an error. Any help (please include an explanation to help me avoid this mistake) will be appreciated. Thanks in advance.

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  • Problem with combination boost::exception and boost::variant

    - by Rick
    Hello all, I have strange problem with two-level variant struct when boost::exception is included. I have following code snippet: #include <boost/variant.hpp> #include <boost/exception/all.hpp> typedef boost::variant< int > StoredValue; typedef boost::variant< StoredValue > ExpressionItem; inline std::ostream& operator << ( std::ostream & os, const StoredValue& stvalue ) { return os;} inline std::ostream& operator << ( std::ostream & os, const ExpressionItem& stvalue ) { return os; } When I try to compile it, I have following error: boost/exception/detail/is_output_streamable.hpp(45): error C2593: 'operator <<' is ambiguous test.cpp(11): could be 'std::ostream &operator <<(std::ostream &,const ExpressionItem &)' [found using argument-dependent lookup] test.cpp(8): or 'std::ostream &operator <<(std::ostream &,const StoredValue &)' [found using argument-dependent lookup] 1> while trying to match the argument list '(std::basic_ostream<_Elem,_Traits>, const boost::error_info<Tag,T>)' 1> with 1> [ 1> _Elem=char, 1> _Traits=std::char_traits<char> 1> ] 1> and 1> [ 1> Tag=boost::tag_original_exception_type, 1> T=const type_info * 1> ] Code snippet is simplified as much as possible, in the real code are structures much more complicated and each variant has five sub-types. When i remove #include and try following test snippet, program is compiled correctly: void TestVariant() { ExpressionItem test; std::stringstream str; str << test; } Could someone please advise me how to define operators << in order to function even when using boost::Exception ? Thanks and regards Rick

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  • G++, compiler warnings, c++ templates

    - by Ian
    During the compilatiion of the C++ program those warnings appeared: c:/MinGW/bin/../lib/gcc/mingw32/3.4.5/../../../../include/c++/3.4.5/bc:/MinGW/bin/../lib/gcc/mingw32/3.4.5/../../../../include/c++/3.4.5/bits/stl_algo.h:2317: instantiated from `void std::partial_sort(_RandomAccessIterator, _RandomAccessIterator, _RandomAccessIterator, _Compare) [with _RandomAccessIterator = __gnu_cxx::__normal_iterator<Object<double>**, std::vector<Object<double>*, std::allocator<Object<double>*> > >, _Compare = sortObjects<double>]' c:/MinGW/bin/../lib/gcc/mingw32/3.4.5/../../../../include/c++/3.4.5/bits/stl_algo.h:2506: instantiated from `void std::__introsort_loop(_RandomAccessIterator, _RandomAccessIterator, _Size, _Compare) [with _RandomAccessIterator = __gnu_cxx::__normal_iterator<Object<double>**, std::vector<Object<double>*, std::allocator<Object<double>*> > >, _Size = int, _Compare = sortObjects<double>]' c:/MinGW/bin/../lib/gcc/mingw32/3.4.5/../../../../include/c++/3.4.5/bits/stl_algo.h:2589: instantiated from `void std::sort(_RandomAccessIterator, _RandomAccessIterator, _Compare) [with _RandomAccessIterator = __gnu_cxx::__normal_iterator<Object<double>**, std::vector<Object<double>*, std::allocator<Object<double>*> > >, _Compare = sortObjects<double>]' io/../structures/objects/../../algorithm/analysis/../../structures/list/ObjectsList.hpp:141: instantiated from `void ObjectsList <T>::sortObjects(unsigned int, T, T, T, T, unsigned int) [with T = double]' I do not why, because all objects have only template parameter T, their local variables are also T. The only place, where I am using double is main. There are objects of type double creating and adding into the ObjectsList... Object <double> o1; ObjectsList <double> olist; olist.push_back(o1); .... T xmin = ..., ymin = ..., xmax = ..., ymax = ...; unsigned int n = ...; olist.sortAllObjects(xmin, ymin, xmax, ymax, n); and comparator template <class T> class sortObjects { private: unsigned int n; T xmin, ymin, xmax, ymax; public: sortObjects ( const T xmin_, const T ymin_, const T xmax_, const T ymax_, const int n_ ) : xmin ( xmin_ ), ymin ( ymin_ ), xmax ( xmax_ ), ymax ( ymax_ ), n ( n_ ) {} bool operator() ( const Object <T> *o1, const Object <T> *o2 ) const { T dmax = (std::max) ( xmax - xmin, ymax - ymin ); T x_max = ( xmax - xmin ) / dmax; T y_max = ( ymax - ymin ) / dmax; ... return ....; } representing ObjectsList method: template <class T> void ObjectsList <T> ::sortAllObjects ( const T xmin, const T ymin, const T xmax, const T ymax, const unsigned int n ) { std::sort ( objects.begin(), objects.end(), sortObjects <T> ( xmin, ymin, xmax, ymax, n ) ); }

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  • Turning temporary stringstream to c_str() in single statement

    - by AshleysBrain
    Consider the following function: void f(const char* str); Suppose I want to generate a string using stringstream and pass it to this function. If I want to do it in one statement, I might try: f((std::ostringstream() << "Value: " << 5).str().c_str()); // error This gives an error: 'str()' is not a member of 'basic_ostream'. OK, so operator<< is returning ostream instead of ostringstream - how about casting it back to an ostringstream? 1) Is this cast safe? f(static_cast<std::ostringstream&>(std::ostringstream() << "Value: " << 5).str().c_str()); // incorrect output Now with this, it turns out for the operator<<("Value: ") call, it's actually calling ostream's operator<<(void*) and printing a hex address. This is wrong, I want the text. 2) Why does operator<< on the temporary std::ostringstream() call the ostream operator? Surely the temporary has a type of 'ostringstream' not 'ostream'? I can cast the temporary to force the correct operator call too! f(static_cast<std::ostringstream&>(static_cast<std::ostringstream&>(std::ostringstream()) << "Value: " << 5).str().c_str()); This appears to work and passes "Value: 5" to f(). 3) Am I relying on undefined behavior now? The casts look unusual. I'm aware the best alternative is something like this: std::ostringstream ss; ss << "Value: " << 5; f(ss.str().c_str()); ...but I'm interested in the behavior of doing it in one line. Suppose someone wanted to make a (dubious) macro: #define make_temporary_cstr(x) (static_cast<std::ostringstream&>(static_cast<std::ostringstream&>(std::ostringstream()) << x).str().c_str()) // ... f(make_temporary_cstr("Value: " << 5)); Would this function as expected?

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  • No Matching Function Error for inserting into a list in c++

    - by Josh Curren
    I am getting an error when I try to insert an item into a list (in C++). The error is that there is no matching function for call to the insert(). I also tried push_front() but got the same error. Here is the error message: main.cpp:38: error: no matching function for call to ‘std::list<Salesperson, std::allocator<Salesperson> >::insert(Salesperson&)’ /usr/lib/gcc/i686-pc-cygwin/4.3.4/include/c++/bits/list.tcc:99: note: candidates are: std::_List_iterator<_Tp> std::list<_Tp, _Alloc>::insert(std::_List_iterator<_Tp>, const _Tp&) [with _Tp = Salesperson, _Alloc = std::allocator<Salesperson>] /usr/lib/gcc/i686-pc-cygwin/4.3.4/include/c++/bits/stl_list.h:961: note: void std::list<_Tp, _Alloc>::insert(std::_List_iterator<_Tp>, size_t, const _Tp&) [with _Tp = Salesperson, _Alloc = std::allocator<Salesperson>] Here is the code: #include <stdlib.h> #include <iostream> #include <fstream> #include <string> #include <list> #include "Salesperson.h" #include "Salesperson.cpp" #include "OrderedList.h" #include "OrderedList.cpp" using namespace std; int main(int argc, char** argv) { cout << "\n------------ Asn 8 - Sales Report ------------" << endl; list<Salesperson> s; int id; string fName, lName; int numOfSales; string year; std::ifstream input("Sales.txt"); while( !std::getline(input, year, ',').eof() ) { input >> id; input >> lName; input >> fName; input >> numOfSales; Salesperson sp = Salesperson( id, fName, lName ); s.insert( sp ); //THIS IS LINE 38 ************************** for( int i = 0; i < numOfSales; i++ ) { double sale; input >> sale; sp.sales.insert( sale ); } } cout << endl; return (EXIT_SUCCESS); }

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  • template; Point<2, double>; Point<3, double>

    - by Oops
    Hi, I want to create my own Point struct it is only for purposes of learning C++. I have the following code: template <int dims, typename T> struct Point { T X[dims]; Point(){} Point( T X0, T X1 ) { X[0] = X0; X[1] = X1; } Point( T X0, T X1, T X2 ) { X[0] = X0; X[1] = X1; X[2] = X2; } Point<dims, int> toint() { //how to distinguish between 2D and 3D ??? Point<dims, int> ret = Point<dims, int>( (int)X[0], (int)X[1]); return ret; } std::string str(){ //how to distinguish between 2D and 3D ??? std::stringstream s; s << "{ X0: " << X[0] << " | X1: " << X[1] << " }"; return s.str(); } }; int main(void) { Point<2, double> p2d = Point<2, double>( 12.3, 45.6 ); Point<3, double> p3d = Point<3, double>( 12.3, 45.6, 78.9 ); Point<2, int> p2i = p2d.toint(); //OK Point<3, int> p3i = p3d.toint(); //m??? std::cout << p2d.str() << std::endl; //OK std::cout << p3d.str() << std::endl; //m??? std::cout << p2i.str() << std::endl; //m??? std::cout << p3i.str() << std::endl; //m??? char c; std::cin >> c; return 0; } of couse until now the output is not what I want. my questions is: how to take care of the dimensions of the Point (2D or 3D) in member functions of the Point? many thanks in advance Oops

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  • curl problems in c++ class

    - by Danilo
    I read a few articles on c++ / curl here on stackoverflow and assembled the following. The main goal is to handle the whole request in an instance of a class -- and maybe later in a secondary thread. My problem is: "content_" seems to stay empty though its the same addr and HttpFetch.h: class HttpFetch { private: CURL *curl; static size_t handle(char * data, size_t size, size_t nmemb, void * p); size_t handle_impl(char * data, size_t size, size_t nmemb); public: std::string content_; static std::string url_; HttpFetch(std::string url); void start(); std::string data(); }; HttpFetch.cpp: HttpFetch::HttpFetch(std::string url) { curl_global_init(CURL_GLOBAL_ALL); //pretty obvious curl = curl_easy_init(); content_.append("Test"); std::cout << &content_ << "\n"; curl_easy_setopt(curl, CURLOPT_URL, &url); curl_easy_setopt(curl, CURLOPT_WRITEDATA, &content_); curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, &HttpFetch::handle); //curl_easy_setopt(curl, CURLOPT_VERBOSE, 1L); //tell curl to output its progress curl_easy_setopt(curl, CURLOPT_FOLLOWLOCATION, 1L); //std::cout << &content_ << "\n"; } void HttpFetch::start() { curl_easy_perform(curl); curl_easy_cleanup(curl); } size_t HttpFetch::handle(char * data, size_t size, size_t nmemb, void * p) { std::string *stuff = reinterpret_cast<std::string*>(p); stuff->append(data, size * nmemb); std::cout << stuff << "\n"; // has content from data in it! return size * nmemb; } main.cpp: #include "HttpFetch.h" int main(int argc, const char * argv[]) { HttpFetch call = *new HttpFetch("http://www.example.com"); call.start(); ::std::cout << call.content_ << "\n" } Thanks in advance

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  • VS2008 -> VS2010 leads to cryptic STL errors

    - by Jakobud
    The following C++ library was successfully compiled in VS2008 http://sourceforge.net/projects/xmlrpcc4win/files/xmlrpcc4win/XmlRpcC4Win1.0.8.zip/download When I open it in VS2010, it goes through the conversion wizard process without any errors. Now, when I attempt to compile it in VS2010, I get some weird STL errors like these: 1>TimXmlRpc.cpp(1018): error C2039: 'back_insert_iterator' : is not a member of 'std' 1>TimXmlRpc.cpp(1018): error C2065: 'back_insert_iterator' : undeclared identifier 1>TimXmlRpc.cpp(1018): error C2275: 'XmlRpcValue::BinaryData' : illegal use of this type as an expression 1>TimXmlRpc.cpp(1018): error C2065: 'ins' : undeclared identifier 1>TimXmlRpc.cpp(1018): error C2039: 'back_inserter' : is not a member of 'std' 1>TimXmlRpc.cpp(1018): error C3861: 'back_inserter': identifier not found 1>TimXmlRpc.cpp(1019): error C2065: 'ins' : undeclared identifier 1>TimXmlRpc.cpp(1031): error C2039: 'back_insert_iterator' : is not a member of 'std' 1>TimXmlRpc.cpp(1031): error C2065: 'back_insert_iterator' : undeclared identifier 1>TimXmlRpc.cpp(1031): error C2275: 'std::vector<_Ty>' : illegal use of this type as an expression 1> with 1> [ 1> _Ty=char 1> ] 1>TimXmlRpc.cpp(1031): error C2065: 'ins' : undeclared identifier 1>TimXmlRpc.cpp(1031): error C2039: 'back_inserter' : is not a member of 'std' 1>TimXmlRpc.cpp(1031): error C3861: 'back_inserter': identifier not found 1>TimXmlRpc.cpp(1032): error C2065: 'ins' : undeclared identifier I'm not sure what to make of some of these. For instance, back_insert_iterator is in fact a member of std, but VS doesn't seem to think it is. How do I fix errors like these? They just don't seem to make much sense so I'm not sure where to begin. Perhaps its something in my project settings? For example, here is line 1018, which gives the std error: std::back_insert_iterator<BinaryData> ins = std::back_inserter(*(u.asBinary)); If anyone could give me some direction I'd appreciate it. I'm new enough to C++ that I'm having a tough time figuring out this one.

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  • Need help modifying C++ application to accept continuous piped input in Linux

    - by GreeenGuru
    The goal is to mine packet headers for URLs visited using tcpdump. So far, I can save a packet header to a file using: tcpdump "dst port 80 and tcp[13] & 0x08 = 8" -A -s 300 | tee -a ./Desktop/packets.txt And I've written a program to parse through the header and extract the URL when given the following command: cat ~/Desktop/packets.txt | ./packet-parser.exe But what I want to be able to do is pipe tcpdump directly into my program, which will then log the data: tcpdump "dst port 80 and tcp[13] & 0x08 = 8" -A -s 300 | ./packet-parser.exe Here is the script as it is. The question is: how do I need to change it to support continuous input from tcpdump? #include <boost/regex.hpp> #include <fstream> #include <cstdio> // Needed to define ios::app #include <string> #include <iostream> int main() { // Make sure to open the file in append mode std::ofstream file_out("/var/local/GreeenLogger/url.log", std::ios::app); if (not file_out) std::perror("/var/local/GreeenLogger/url.log"); else { std::string text; // Get multiple lines of input -- raw std::getline(std::cin, text, '\0'); const boost::regex pattern("GET (\\S+) HTTP.*?[\\r\\n]+Host: (\\S+)"); boost::smatch match_object; bool match = boost::regex_search(text, match_object, pattern); if(match) { std::string output; output = match_object[2] + match_object[1]; file_out << output << '\n'; std::cout << output << std::endl; } file_out.close(); } } Thank you ahead of time for the help!

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  • Academic question: typename

    - by Arman
    Hi, recently I accounted with a "simple problem" of porting code from VC++ to gcc/intel. The code is compiles w/o error on VC++: #include <vector> using std::vector; template <class T> void test_vec( std::vector<T> &vec) { typedef std::vector<T> M; /*==> add here typename*/ M::iterator ib=vec.begin(),ie=vec.end(); }; int main() { vector<double> x(100, 10); test_vec<double>(x); return 0; } then with g++ we have some unclear errors: g++ t.cpp t.cpp: In function 'void test_vec(std::vector<T, std::allocator<_CharT> >&)': t.cpp:13: error: expected `;' before 'ie' t.cpp: In function 'void test_vec(std::vector<T, std::allocator<_CharT> >&) [with T = double]': t.cpp:18: instantiated from here t.cpp:12: error: dependent-name 'std::M::iterator' is parsed as a non-type, but instantiation yields a type t.cpp:12: note: say 'typename std::M::iterator' if a type is meant If we add typename before iterator the code will compile w/o pb. If it is possible to make a compiler which can understand the code written in the more "natural way", then for me is unclear why we should add typename? Which rules of "C++ standards"(if there are some) will be broken if we allow all compilers to use without "typename"? kind regards Arman.

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  • Accelerated C++, problem 5-6 (copying values from inside a vector to the front)

    - by Darel
    Hello, I'm working through the exercises in Accelerated C++ and I'm stuck on question 5-6. Here's the problem description: (somewhat abbreviated, I've removed extraneous info.) 5-6. Write the extract_fails function so that it copies the records for the passing students to the beginning of students, and then uses the resize function to remove the extra elements from the end of students. (students is a vector of student structures. student structures contain an individual student's name and grades.) More specifically, I'm having trouble getting the vector.insert function to properly copy the passing student structures to the start of the vector students. Here's the extract_fails function as I have it so far (note it doesn't resize the vector yet, as directed by the problem description; that should be trivial once I get past my current issue.) // Extract the students who failed from the "students" vector. void extract_fails(vector<Student_info>& students) { typedef vector<Student_info>::size_type str_sz; typedef vector<Student_info>::iterator iter; iter it = students.begin(); str_sz i = 0, count = 0; while (it != students.end()) { // fgrade tests wether or not the student failed if (!fgrade(*it)) { // if student passed, copy to front of vector students.insert(students.begin(), it, it); // tracks of the number of passing students(so we can properly resize the array) count++; } cout << it->name << endl; // output to verify that each student is iterated to it++; } } The code compiles and runs, but the students vector isn't adding any student structures to its front. My program's output displays that the students vector is unchanged. Here's my complete source code, followed by a sample input file (I redirect input from the console by typing " < grades" after the compiled program name at the command prompt.) #include <iostream> #include <string> #include <algorithm> // to get the declaration of `sort' #include <stdexcept> // to get the declaration of `domain_error' #include <vector> // to get the declaration of `vector' //driver program for grade partitioning examples using std::cin; using std::cout; using std::endl; using std::string; using std::domain_error; using std::sort; using std::vector; using std::max; using std::istream; struct Student_info { std::string name; double midterm, final; std::vector<double> homework; }; bool compare(const Student_info&, const Student_info&); std::istream& read(std::istream&, Student_info&); std::istream& read_hw(std::istream&, std::vector<double>&); double median(std::vector<double>); double grade(double, double, double); double grade(double, double, const std::vector<double>&); double grade(const Student_info&); bool fgrade(const Student_info&); void extract_fails(vector<Student_info>& v); int main() { vector<Student_info> vs; Student_info s; string::size_type maxlen = 0; while (read(cin, s)) { maxlen = max(maxlen, s.name.size()); vs.push_back(s); } sort(vs.begin(), vs.end(), compare); extract_fails(vs); // display the new, modified vector - it should be larger than // the input vector, due to some student structures being // added to the front of the vector. cout << "count: " << vs.size() << endl << endl; vector<Student_info>::iterator it = vs.begin(); while (it != vs.end()) cout << it++->name << endl; return 0; } // Extract the students who failed from the "students" vector. void extract_fails(vector<Student_info>& students) { typedef vector<Student_info>::size_type str_sz; typedef vector<Student_info>::iterator iter; iter it = students.begin(); str_sz i = 0, count = 0; while (it != students.end()) { // fgrade tests wether or not the student failed if (!fgrade(*it)) { // if student passed, copy to front of vector students.insert(students.begin(), it, it); // tracks of the number of passing students(so we can properly resize the array) count++; } cout << it->name << endl; // output to verify that each student is iterated to it++; } } bool compare(const Student_info& x, const Student_info& y) { return x.name < y.name; } istream& read(istream& is, Student_info& s) { // read and store the student's name and midterm and final exam grades is >> s.name >> s.midterm >> s.final; read_hw(is, s.homework); // read and store all the student's homework grades return is; } // read homework grades from an input stream into a `vector<double>' istream& read_hw(istream& in, vector<double>& hw) { if (in) { // get rid of previous contents hw.clear(); // read homework grades double x; while (in >> x) hw.push_back(x); // clear the stream so that input will work for the next student in.clear(); } return in; } // compute the median of a `vector<double>' // note that calling this function copies the entire argument `vector' double median(vector<double> vec) { typedef vector<double>::size_type vec_sz; vec_sz size = vec.size(); if (size == 0) throw domain_error("median of an empty vector"); sort(vec.begin(), vec.end()); vec_sz mid = size/2; return size % 2 == 0 ? (vec[mid] + vec[mid-1]) / 2 : vec[mid]; } // compute a student's overall grade from midterm and final exam grades and homework grade double grade(double midterm, double final, double homework) { return 0.2 * midterm + 0.4 * final + 0.4 * homework; } // compute a student's overall grade from midterm and final exam grades // and vector of homework grades. // this function does not copy its argument, because `median' does so for us. double grade(double midterm, double final, const vector<double>& hw) { if (hw.size() == 0) throw domain_error("student has done no homework"); return grade(midterm, final, median(hw)); } double grade(const Student_info& s) { return grade(s.midterm, s.final, s.homework); } // predicate to determine whether a student failed bool fgrade(const Student_info& s) { return grade(s) < 60; } Sample input file: Moo 100 100 100 100 100 100 100 100 Fail1 45 55 65 80 90 70 65 60 Moore 75 85 77 59 0 85 75 89 Norman 57 78 73 66 78 70 88 89 Olson 89 86 70 90 55 73 80 84 Peerson 47 70 82 73 50 87 73 71 Baker 67 72 73 40 0 78 55 70 Davis 77 70 82 65 70 77 83 81 Edwards 77 72 73 80 90 93 75 90 Fail2 55 55 65 50 55 60 65 60 Thanks to anyone who takes the time to look at this!

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  • What is difference between my atoi() calls?

    - by Lucas
    I have a big number stored in a string and try to extract a single digit. But what are the differences between those calls? #include <iostream> #include <string> int main(){ std::string bigNumber = "93485720394857230"; char tmp = bigNumber.at(5); int digit = atoi(&tmp); int digit2 = atoi(&bigNumber.at(5)) int digit3 = atoi(&bigNumber.at(12)); std::cout << "digit: " << digit << std::endl; std::cout << "digit2: " << digit2 << std::endl; std::cout << "digit3: " << digit3 << std::endl; } This will produce the following output. digit: 7 digit2: 2147483647 digit3: 57230 The first one is the desired result. The second one seems to me to be a random number, which I cannot find in the string. The third one is the end of the string, but not just a single digit as I expected, but up from the 12th index to the end of the string. Can somebody explain the different outputs to me? EDIT: Would this be an acceptable solution? char tmp[2] = {bigNumber.at(5), '\0'}; int digit = atoi(tmp); std::cout << "digit: " << digit << std::endl;

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  • Using the Proxy pattern with C++ iterators

    - by Billy ONeal
    Hello everyone :) I've got a moderately complex iterator written which wraps the FindXFile apis on Win32. (See previous question) In order to avoid the overhead of constructing an object that essentially duplicates the work of the WIN32_FIND_DATAW structure, I have a proxy object which simply acts as a sort of const reference to the single WIN32_FIND_DATAW which is declared inside the noncopyable innards of the iterator. This is great because Clients do not pay for construction of irrelevant information they will probably not use (most of the time people are only interested in file names), and Clients can get at all the information provided by the FindXFile APIs if they need or want this information. This becomes an issue though because there is only ever a single copy of the object's actual data. Therefore, when the iterator is incrememnted, all of the proxies are invalidated (set to whatever the next file pointed to by the iterator is). I'm concerned if this is a major problem, because I can think of a case where the proxy object would not behave as somebody would expect: std::vector<MyIterator::value_type> files; std::copy(MyIterator("Hello"), MyIterator(), std::back_inserter(files)); because the vector contains nothing but a bunch of invalid proxies at that point. Instead, clients need to do something like: std::vector<std::wstring> filesToSearch; std::transform( DirectoryIterator<FilesOnly>(L"C:\\Windows\\*"), DirectoryIterator<FilesOnly>(), std::back_inserter(filesToSearch), std::mem_fun_ref(&DirectoryIterator<FilesOnly>::value_type::GetFullFileName) ); Seeing this, I can see why somebody might dislike what the standard library designers did with std::vector<bool>. I'm still wondering though: is this a reasonable trade off in order to achieve (1) and (2) above? If not, is there any way to still achieve (1) and (2) without the proxy?

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  • Boost binding a function taking a reference

    - by Jamie Cook
    Hi all, I am having problems compiling the following snippet int temp; vector<int> origins; vector<string> originTokens = OTUtils::tokenize(buffer, ","); // buffer is a char[] array // original loop BOOST_FOREACH(string s, originTokens) { from_string(temp, s); origins.push_back(temp); } // I'd like to use this to replace the above loop std::transform(originTokens.begin(), originTokens.end(), origins.begin(), boost::bind<int>(&FromString<int>, boost::ref(temp), _1)); where the function in question is // the third parameter should be one of std::hex, std::dec or std::oct template <class T> bool FromString(T& t, const std::string& s, std::ios_base& (*f)(std::ios_base&) = std::dec) { std::istringstream iss(s); return !(iss >> f >> t).fail(); } the error I get is 1>Compiling with Intel(R) C++ 11.0.074 [IA-32]... (Intel C++ Environment) 1>C:\projects\svn\bdk\Source\deps\boost_1_42_0\boost/bind/bind.hpp(303): internal error: assertion failed: copy_default_arg_expr: rout NULL, no error (shared/edgcpfe/il.c, line 13919) 1> 1> return unwrapper<F>::unwrap(f, 0)(a[base_type::a1_], a[base_type::a2_]); 1> ^ 1> 1>icl: error #10298: problem during post processing of parallel object compilation Google is being unusually unhelpful so I hope that some one here can provide some insights.

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  • How do I refactor code into a subroutine but allow for early exit?

    - by deworde
    There's a really obvious refactoring opportunity in this (working) code. bool Translations::compatibleNICodes(const Rule& rule, const std::vector<std::string>& nicodes) { bool included = false; // Loop through the ni codes. for(std::vector<std::string> iter = nicodes.begin(); iter != nicodes.end(); ++iter) { // Match against the ni codes of the rule if(rule.get_ni1() == *iter) { // If there's a match, check if the rule is include or exclude const std::string flag = rule.get_op1(); // If include, code is included unless a later rule excludes it if(flag == "INCLUDE"){ included = true; } // If exclude, code is specifically excluded else if(flag == "EXCLUDE"){ return false; } } if(rule.get_ni2() == *iter) { const std::string flag = rule.get_op2(); if(flag == "INCLUDE"){ included = true; } else if(flag == "EXCLUDE"){ return false; } } if(rule.get_ni3() == *iter) { const std::string flag = rule.get_op3(); if(flag == "INCLUDE"){ included = true; } else if(flag == "EXCLUDE"){ return false; } } if(rule.get_ni4() == *iter) { const std::string flag = rule.get_op4(); if(flag == "INCLUDE"){ included = true; } else if(flag == "EXCLUDE"){ return false; } } if(rule.get_ni5() == *iter) { const std::string flag = rule.get_op5(); if(flag == "INCLUDE"){ included = true; } else if(flag == "EXCLUDE"){ return false; } } } return included; } The problem is that I can't get around the problem that I want to exit early if it's an exclude statement. Note that I can't change the structure of the Rule class. Any advice?

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  • C++ Pointer member function with templates assignment with a member function of another class

    - by Agusti
    Hi, I have this class: class IShaderParam{ public: std::string name_value; }; template<class TParam> class TShaderParam:public IShaderParam{ public: void (TShaderParam::*send_to_shader)( const TParam&,const std::string&); TShaderParam():send_to_shader(NULL){} TParam value; void up_to_shader(); }; typedef TShaderParam<float> FloatShaderParam; typedef TShaderParam<D3DXVECTOR3> Vec3ShaderParam; In another class, I have a vector of IShaderParams* and functions that i want to send to "send_to_shader". I'm trying assign the reference of these functions like this: Vec3ShaderParam *_param = new Vec3ShaderParam; _param-send_to_shader = &TShader::setVector3; This is the function: void TShader::setVector3(const D3DXVECTOR3 &vec, const std::string &name){ //... } And this is the class with IshaderParams*: class TShader{ std::vector params; public: Shader effect; std::string technique_name; TShader(std::string& afilename):effect(NULL){}; ~TShader(); void setVector3(const D3DXVECTOR3 &vec, const std::string &name); When I compile the project with Visual Studio C++ Express 2008 I recieve this error: Error 2 error C2440: '=' :can't make the conversion 'void (__thiscall TShader::* )(const D3DXVECTOR3 &,const std::string &)' a 'void (__thiscall TShaderParam::* )(const TParam &,const std::string &)' c:\users\isagoras\documents\mcv\afoc\shader.cpp 127 Can I do the assignment? No? I don't know how :-S Yes, I know that I can achieve the same objective with other techniques, but I want to know how can I do this..

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  • Increasing time resolution of BOOST::progress timer

    - by feelfree
    BOOST::progress_timer is a very useful class to measure the running time of a function. However, the default implementation of progress_timer is not accurate enough and a possible way of increasing time resolution is to reconstruct a new class as the following codes show: #include <boost/progress.hpp> #include <boost/static_assert.hpp> template<int N=2> class new_progress_timer:public boost::timer { public: new_progress_timer(std::ostream &os=std::cout):m_os(os) { BOOST_STATIC_ASSERT(N>=0 &&N<=10); } ~new_progress_timer(void) { try { std::istream::fmtflags old_flags = m_os.setf(std::istream::fixed,std::istream::floatfield); std::streamsize old_prec = m_os.precision(N); m_os<<elapsed()<<"s\n" <<std::endl; m_os.flags(old_flags); m_os.precison(old_prec); } catch(...) { } } private: std::ostream &m_os; }; However, when I compile the codes with VC10, the following error appear: 'precison' : is not a member of 'std::basic_ostream<_Elem,_Traits>' Any ideas? Thanks.

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