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  • Alias for a C++ template?

    - by porgarmingduod
    typedef boost::interprocess::managed_shared_memory::segment_manager segment_manager_t; // Works fine, segment_manager is a class typedef boost::interprocess::adaptive_pool allocator_t; // Can't do this, adaptive_pool is a template The idea is that if I want to switch between boost interprocess' several different options for shared memory and allocators, I just modify the typedefs. Unfortunately the allocators are templates, so I can't typedef the allocator I want to use. Is there a way to achieve an alias to a template in C++? (Except for the obvious #define ALLOCATOR_T boost::interprocess::adaptive_pool)

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  • c++ template function compiles in header but not implementation

    - by flies
    I'm trying to learn templates and I've run into this confounding error. I'm declaring some functions in a header file and I want to make a separate implementation file where the functions will be defined. Here's the code that calls the header (dum.cpp): #include <iostream> #include <vector> #include <string> #include "dumper2.h" int main() { std::vector<int> v; for (int i=0; i<10; i++) { v.push_back(i); } test(); std::string s = ", "; dumpVector(v,s); } now, here's a working header file (dumper2.h): #include <iostream> #include <string> #include <vector> void test(); template <class T> void dumpVector( std::vector<T> v,std::string sep); template <class T> void dumpVector(std::vector<T> v, std::string sep) { typename std::vector<T>::iterator vi; vi = v.begin(); std::cout << *vi; vi++; for (;vi<v.end();vi++) { std::cout << sep << *vi ; } std::cout << "\n"; return; } with implentation (dumper2.cpp): #include <iostream> #include "dumper2.h" void test() { std::cout << "!olleh dlrow\n"; } the weird thing is that if I move the code that defines dumpVector from the .h to the .cpp file, I get the following error: g++ -c dumper2.cpp -Wall -Wno-deprecated g++ dum.cpp -o dum dumper2.o -Wall -Wno-deprecated /tmp/ccKD2e3G.o: In function `main': dum.cpp:(.text+0xce): undefined reference to `void dumpVector<int>(std::vector<int, std::allocator<int> >, std::basic_string<char, std::char_traits<char>, std::allocator<char> >)' collect2: ld returned 1 exit status make: *** [dum] Error 1 So why does it work one way and not the other? Clearly the compiler can find test(), so why can't it find dumpVector?

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  • C++: Can't use std::wstringstream

    - by Rosarch
    For some reason, my project won't compile when I try to create a wstringstream: std::wstringstream stringstream; This causes error C2079: 'stringstream' uses undefined class 'std::basic_stringstream<_Elem, _Traits, _Alloc with [_Elem=wchar_t, _Traits=std::char_traits, _Alloc=std::allocator' What am I doing wrong?

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  • Access Voilation in std::pair

    - by sameer karjatkar
    I have an application which is trying to populate a pair . Out of no where the application crashes . The Windbg analysis on the crash dump suggest PRIMARY_PROBLEM_CLASS: INVALID_POINTER_READ DEFAULT_BUCKET_ID: INVALID_POINTER_READ STACK_TEXT: 0389f1dc EPFilter32!std::vector,std::allocator ::size+0xc INVALID_POINTER_READ_c0000005_Test.DLL!std::vector_std::pair_unsigned_int, unsigned_int_,std::allocator_std::pair_unsigned_int,unsigned_int___::size Following is the statement in the code where it fails const branch_info& b1 = en1.m_branches[i1]; where branch_info is std::pair and the en1.m_branches[i1] fetches me a pair value

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  • Any pitfalls using char* instead of void* when writing cross platform code?

    - by UberMongoose
    Is there any pitfalls when using char*'s to write cross platform code that does memory access? I'm working on a play memory allocator to better understand how to debug memmory issues. I have come to believe char*'s are preferable because of the ability to do pointer arithmetic and derefernce them over void*'s, is that true? Do the following assumptions always hold true on different common platforms? sizeof(char) == 1 sizeof(char*) == sizeof(void*) sizeof(char*) == sizeof(size_t)

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  • How to proceed when a bug in open source libraries is suspected?

    - by Suma
    We are using some open source libraries in our projects. Sometimes there are some issues found in some of them (most likely library bugs, but it may also be a wrong usage from our side, especially when sometimes documentation is not exactly 100 % complete). As the libraries are often quite complex, debugging them to pinpoint the source of the problem is sometimes quite hard. Can you help me to summarize what other options are there and how to exactly proceed with them? I have just recently hit some strange problems when using TCMalloc (Google scalable memory allocator) on Windows, so I would most welcome answers which would apply to this particular library, but more general answers are good as well. 1) Ask the maintainer/owner of the project for assistance. How can this be done? 2) Hire someone to identify and fix the issue. How to do this? How can I find someone with enough expertise in some particular library? ... any other options?

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  • Linker errors between multiple projects in Visual C++

    - by rlbond
    Hi, I have a solution with multiple projects. I have a "main" project, which acts as a menu and from there, the user can access any of the other projects. On this main project, I get linker errors for every function called. How do I avoid these linker errors? I set the project dependencies already in the "Project Dependencies..." dialog. Thanks EDIT -- I did as suggested and added the output folder to the linker's additional directories. Now, however, I get a million errors as follows: 3msvcprtd.lib(MSVCP90D.dll) : error LNK2005: "public: void __thiscall std::basic_ios ::setstate(int,bool)" (?setstate@?$basic_ios@DU?$char_traits@D@std@@@std@@QAEXH_N@Z) already defined in panels.lib(panel_main.obj) 3msvcprtd.lib(MSVCP90D.dll) : error LNK2005: "public: int __thiscall std::ios_base::width(int)" (?width@ios_base@std@@QAEHH@Z) already defined in panels.lib(panel_main.obj) 3msvcprtd.lib(MSVCP90D.dll) : error LNK2005: "public: int __thiscall std::basic_streambuf ::sputn(char const *,int)" (?sputn@?$basic_streambuf@DU?$char_traits@D@std@@@std@@QAEHPBDH@Z) already defined in panels.lib(panel_main.obj) 3msvcprtd.lib(MSVCP90D.dll) : error LNK2005: "public: static bool __cdecl std::char_traits::eq_int_type(int const &,int const &)" (?eq_int_type@?$char_traits@D@std@@SA_NABH0@Z) already defined in panels.lib(panel_main.obj) 3msvcprtd.lib(MSVCP90D.dll) : error LNK2005: "public: static int __cdecl std::char_traits::eof(void)" (?eof@?$char_traits@D@std@@SAHXZ) already defined in panels.lib(panel_main.obj) 3msvcprtd.lib(MSVCP90D.dll) : error LNK2005: "public: int __thiscall std::basic_streambuf ::sputc(char)" (?sputc@?$basic_streambuf@DU?$char_traits@D@std@@@std@@QAEHD@Z) already defined in panels.lib(panel_main.obj) 3msvcprtd.lib(MSVCP90D.dll) : error LNK2005: "public: class std::basic_streambuf * __thiscall std::basic_ios ::rdbuf(void)const " (?rdbuf@?$basic_ios@DU?$char_traits@D@std@@@std@@QBEPAV?$basic_streambuf@DU?$char_traits@D@std@@@2@XZ) already defined in panels.lib(panel_main.obj) 3msvcprtd.lib(MSVCP90D.dll) : error LNK2005: "public: char __thiscall std::basic_ios ::fill(void)const " (?fill@?$basic_ios@DU?$char_traits@D@std@@@std@@QBEDXZ) already defined in panels.lib(panel_main.obj) 3msvcprtd.lib(MSVCP90D.dll) : error LNK2005: "public: int __thiscall std::ios_base::flags(void)const " (?flags@ios_base@std@@QBEHXZ) already defined in panels.lib(panel_main.obj) 3msvcprtd.lib(MSVCP90D.dll) : error LNK2005: "public: int __thiscall std::ios_base::width(void)const " (?width@ios_base@std@@QBEHXZ) already defined in panels.lib(panel_main.obj) 3msvcprtd.lib(MSVCP90D.dll) : error LNK2005: "public: static unsigned int __cdecl std::char_traits::length(char const *)" (?length@?$char_traits@D@std@@SAIPBD@Z) already defined in panels.lib(panel_main.obj) 3msvcprtd.lib(MSVCP90D.dll) : error LNK2005: "public: class std::basic_ostream & __thiscall std::basic_ostream ::flush(void)" (?flush@?$basic_ostream@DU?$char_traits@D@std@@@std@@QAEAAV12@XZ) already defined in panels.lib(panel_main.obj) 3msvcprtd.lib(MSVCP90D.dll) : error LNK2005: "public: class std::basic_ostream * __thiscall std::basic_ios ::tie(void)const " (?tie@?$basic_ios@DU?$char_traits@D@std@@@std@@QBEPAV?$basic_ostream@DU?$char_traits@D@std@@@2@XZ) already defined in panels.lib(panel_main.obj) 3msvcprtd.lib(MSVCP90D.dll) : error LNK2005: "public: bool __thiscall std::ios_base::good(void)const " (?good@ios_base@std@@QBE_NXZ) already defined in panels.lib(panel_main.obj) 3msvcprtd.lib(MSVCP90D.dll) : error LNK2005: "public: void __thiscall std::basic_ostream ::_Osfx(void)" (?_Osfx@?$basic_ostream@DU?$char_traits@D@std@@@std@@QAEXXZ) already defined in panels.lib(panel_main.obj) 3msvcprtd.lib(MSVCP90D.dll) : error LNK2005: "public: void __thiscall std::basic_streambuf ::_Lock(void)" (?_Lock@?$basic_streambuf@DU?$char_traits@D@std@@@std@@QAEXXZ) already defined in panels.lib(panel_main.obj) 3msvcprtd.lib(MSVCP90D.dll) : error LNK2005: "public: void __thiscall std::basic_streambuf ::_Unlock(void)" (?_Unlock@?$basic_streambuf@DU?$char_traits@D@std@@@std@@QAEXXZ) already defined in panels.lib(panel_main.obj) 3msvcprtd.lib(MSVCP90D.dll) : error LNK2005: "public: class std::locale::facet * __thiscall std::locale::facet::_Decref(void)" (?_Decref@facet@locale@std@@QAEPAV123@XZ) already defined in panels.lib(panel_main.obj) 3libcpmtd.lib(ios.obj) : error LNK2005: "private: static void __cdecl std::ios_base::_Ios_base_dtor(class std::ios_base *)" (?_Ios_base_dtor@ios_base@std@@CAXPAV12@@Z) already defined in msvcprtd.lib(MSVCP90D.dll) 3libcpmtd.lib(ios.obj) : error LNK2005: "public: static void __cdecl std::ios_base::_Addstd(class std::ios_base *)" (?_Addstd@ios_base@std@@SAXPAV12@@Z) already defined in msvcprtd.lib(MSVCP90D.dll) 3libcpmtd.lib(locale0.obj) : error LNK2005: "void __cdecl _AtModuleExit(void (__cdecl*)(void))" (?_AtModuleExit@@YAXP6AXXZ@Z) already defined in msvcprtd.lib(locale0_implib.obj) 3libcpmtd.lib(locale0.obj) : error LNK2005: __Fac_tidy already defined in msvcprtd.lib(locale0_implib.obj) 3libcpmtd.lib(locale0.obj) : error LNK2005: "private: static void __cdecl std::locale::facet::facet_Register(class std::locale::facet *)" (?facet_Register@facet@locale@std@@CAXPAV123@@Z) already defined in msvcprtd.lib(locale0_implib.obj) 3libcpmtd.lib(locale0.obj) : error LNK2005: "private: static class std::locale::_Locimp * __cdecl std::locale::_Getgloballocale(void)" (?_Getgloballocale@locale@std@@CAPAV_Locimp@12@XZ) already defined in msvcprtd.lib(MSVCP90D.dll) 3libcpmtd.lib(locale0.obj) : error LNK2005: "private: static class std::locale::_Locimp * __cdecl std::locale::_Init(void)" (?_Init@locale@std@@CAPAV_Locimp@12@XZ) already defined in msvcprtd.lib(MSVCP90D.dll) 3libcpmtd.lib(locale0.obj) : error LNK2005: "public: static void __cdecl std::_Locinfo::_Locinfo_ctor(class std::_Locinfo *,class std::basic_string,class std::allocator const &)" (?_Locinfo_ctor@_Locinfo@std@@SAXPAV12@ABV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@2@@Z) already defined in msvcprtd.lib(MSVCP90D.dll) 3libcpmtd.lib(locale0.obj) : error LNK2005: "public: static void __cdecl std::_Locinfo::_Locinfo_dtor(class std::_Locinfo *)" (?_Locinfo_dtor@_Locinfo@std@@SAXPAV12@@Z) already defined in msvcprtd.lib(MSVCP90D.dll) 3libcpmtd.lib(xlock.obj) : error LNK2005: "public: __thiscall std::_Lockit::_Lockit(int)" (??0_Lockit@std@@QAE@H@Z) already defined in msvcprtd.lib(MSVCP90D.dll) 3libcpmtd.lib(xlock.obj) : error LNK2005: "public: __thiscall std::_Lockit::~_Lockit(void)" (??1_Lockit@std@@QAE@XZ) already defined in msvcprtd.lib(MSVCP90D.dll)

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  • STL operator= behavior change with Visual Studio 2010?

    - by augnob
    Hi, I am attempting to compile QtScriptGenerator (gitorious) with Visual Studio 2010 (C++) and have run into a compile error. In searching for a solution, I have seen occasional references to compile breakages introduced since VS2008 due to changes in VS2010's implementation of STL and/or c++0x conformance changes. Any ideas what is happening below, or how I could go about fixing it? If the offending code appeared to be QtScriptGenerator's, I think I would have an easier time fixing it.. but it appears to me that the offending code may be in VS2010's STL implementation and I may be required to create a workaround? PS. I am pretty unfamiliar with templates and STL. I have a background in embedded and console projects where such things have until recently often been avoided to reduce memory consumption and cross-compiler risks. C:\Program Files\Microsoft Visual Studio 10.0\VC\INCLUDE\xutility(275) : error C2679: binary '=' : no operator found which takes a right-hand operand of type 'rpp::pp_output_iterator<_Container>' (or there is no acceptable conversion) with [ _Container=std::string ] c:\qt\qtscriptgenerator\generator\parser\rpp\pp-iterator.h(75): could be 'rpp::pp_output_iterator<_Container> &rpp::pp_output_iterator<_Container>::operator =(const char &)' with [ _Container=std::string ] while trying to match the argument list '(rpp::pp_output_iterator<_Container>, rpp::pp_output_iterator<_Container>)' with [ _Container=std::string ] C:\Program Files\Microsoft Visual Studio 10.0\VC\INCLUDE\xutility(2176) : see reference to function template instantiation '_Iter &std::_Rechecked<_OutIt,_OutIt>(_Iter &,_UIter)' being compiled with [ _Iter=rpp::pp_output_iterator<std::string>, _OutIt=rpp::pp_output_iterator<std::string>, _UIter=rpp::pp_output_iterator<std::string> ] c:\qt\qtscriptgenerator\generator\parser\rpp\pp-internal.h(83) : see reference to function template instantiation '_OutIt std::copy<std::_String_iterator<_Elem,_Traits,_Alloc>,_OutputIterator>(_InIt,_InIt,_OutIt)' being compiled with [ _OutIt=rpp::pp_output_iterator<std::string>, _Elem=char, _Traits=std::char_traits<char>, _Alloc=std::allocator<char>, _OutputIterator=rpp::pp_output_iterator<std::string>, _InIt=std::_String_iterator<char,std::char_traits<char>,std::allocator<char>> ] c:\qt\qtscriptgenerator\generator\parser\rpp\pp-engine-bits.h(500) : see reference to function template instantiation 'void rpp::_PP_internal::output_line<_OutputIterator>(const std::string &,int,_OutputIterator)' being compiled with [ _OutputIterator=rpp::pp_output_iterator<std::string> ] C:\Program Files\Microsoft Visual Studio 10.0\VC\INCLUDE\xutility(275) : error C2582: 'operator =' function is unavailable in 'rpp::pp_output_iterator<_Container>' with [ _Container=std::string ] Here's some context.. pp-internal.h-- #ifndef PP_INTERNAL_H #define PP_INTERNAL_H #include <algorithm> #include <stdio.h> namespace rpp { namespace _PP_internal { .. 68 template <typename _OutputIterator> 69 void output_line(const std::string &__filename, int __line, _OutputIterator __result) 70 { 71 std::string __msg; 72 73 __msg += "# "; 74 75 char __line_descr[16]; 76 pp_snprintf (__line_descr, 16, "%d", __line); 77 __msg += __line_descr; 78 79 __msg += " \""; 80 81 if (__filename.empty ()) 82 __msg += "<internal>"; 83 else 84 __msg += __filename; 85 86 __msg += "\"\n"; 87 std::copy (__msg.begin (), __msg.end (), __result); 88 }

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  • C++ std::vector insert segfault

    - by ArunSaha
    I am writing a test program to understand vector's better. In one of the scenarios, I am trying to insert a value into the vector at a specified position. The code compiles clean. However, on execution, it is throwing a Segmentation Fault from the v8.insert(..) line (see code below). I am confused. Can somebody point me to what is wrong in my code? #define UNIT_TEST(x) assert(x) #define ENSURE(x) assert(x) #include <vector> typedef std::vector< int > intVector; typedef std::vector< int >::iterator intVectorIterator; typedef std::vector< int >::const_iterator intVectorConstIterator; intVectorIterator find( intVector v, int key ); void test_insert(); intVectorIterator find( intVector v, int key ) { for( intVectorIterator it = v.begin(); it != v.end(); ++it ) { if( *it == key ) { return it; } } return v.end(); } void test_insert() { const int values[] = {10, 20, 30, 40, 50}; const size_t valuesLength = sizeof( values ) / sizeof( values[ 0 ] ); size_t index = 0; const int insertValue = 5; intVector v8; for( index = 0; index < valuesLength; ++index ) { v8.push_back( values[ index ] ); } ENSURE( v8.size() == valuesLength ); for( index = 0; index < valuesLength; ++index ) { printf( "index = %u\n", index ); intVectorIterator it = find( v8, values[ index ] ); ENSURE( it != v8.end() ); ENSURE( *it == values[ index ] ); // intVectorIterator itToInsertedItem = v8.insert( it, insertValue ); // line 51 // UNIT_TEST( *itToInsertedItem == insertValue ); } } int main() { test_insert(); return 0; } $ ./a.out index = 0 Segmentation Fault (core dumped) (gdb) bt #0 0xff3a03ec in memmove () from /platform/SUNW,T5140/lib/libc_psr.so.1 #1 0x00012064 in std::__copy_move_backward<false, true, std::random_access_iterator_tag>::__copy_move_b<int> (__first=0x23e48, __last=0x23450, __result=0x23454) at /local/gcc/4.4.1/lib/gcc/sparc-sun-solaris2.10/4.4.1/../../../../include/c++/4.4.1/bits/stl_algobase.h:575 #2 0x00011f08 in std::__copy_move_backward_a<false, int*, int*> (__first=0x23e48, __last=0x23450, __result=0x23454) at /local/gcc/4.4.1/lib/gcc/sparc-sun-solaris2.10/4.4.1/../../../../include/c++/4.4.1/bits/stl_algobase.h:595 #3 0x00011d00 in std::__copy_move_backward_a2<false, int*, int*> (__first=0x23e48, __last=0x23450, __result=0x23454) at /local/gcc/4.4.1/lib/gcc/sparc-sun-solaris2.10/4.4.1/../../../../include/c++/4.4.1/bits/stl_algobase.h:605 #4 0x000119b8 in std::copy_backward<int*, int*> (__first=0x23e48, __last=0x23450, __result=0x23454) at /local/gcc/4.4.1/lib/gcc/sparc-sun-solaris2.10/4.4.1/../../../../include/c++/4.4.1/bits/stl_algobase.h:640 #5 0x000113ac in std::vector<int, std::allocator<int> >::_M_insert_aux (this=0xffbfeba0, __position=..., __x=@0xffbfebac) at /local/gcc/4.4.1/lib/gcc/sparc-sun-solaris2.10/4.4.1/../../../../include/c++/4.4.1/bits/vector.tcc:308 #6 0x00011120 in std::vector<int, std::allocator<int> >::insert (this=0xffbfeba0, __position=..., __x=@0xffbfebac) at /local/gcc/4.4.1/lib/gcc/sparc-sun-solaris2.10/4.4.1/../../../../include/c++/4.4.1/bits/vector.tcc:126 #7 0x00010bc0 in test_insert () at vector_insert_test.cpp:51 #8 0x00010c48 in main () at vector_insert_test.cpp:58 (gdb) q

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  • Counting number of times an item occurs in a linked list

    - by HanaCHaN92
    Here is the assignment: Here's the assignment: Implement a method countValue() that counts the number of times an item occurs in a linked list. Remember to use the STL list. int countValue(list front, const int item); Generate 20 random numbers in the range of 0 to 4, and insert each number in the linked list. Output the list by using a method which you would call writeLinkedList which you would add to the ListP.cpp. In a loop, call the method countValue() , and display the number of occurrences of each value from 0 to 4 in the list. Remember that all the above is to be included in the file ListP.ccp Run: 2 3 4 0 1 0 2 4 2 3 3 4 3 3 3 0 0 2 0 2 0 : 5, 1 : 1, 2 : 5, 3 : 6, 4 : 3 and here is what I have so far: #include<iostream> #include<list> #include<tchar.h> int countValue(list<int> front, const int item); using namespace std; int _tmain(int argc, _TCHAR* argv[]){ list<int> front; int listCount; cout << "Enter the size of the list: "; cin >> listCount; for (int i = 1; i <= listCount; i++) front.insert(rand()%5); cout << "Original List of Values: " << endl; //writeLinkedList(front, " "); cout << endl; for(int j=0;j<5;++j) cout << countValue (front,j) << endl; cout << endl; return 0; } int countValue(list<int> front, const int item) { int count0; int count1; int count2; int count3; int count4; list<int> *List; for(list<int>::iterator i = front.begin(); i != front.end(); i++) { if(List->item == 0) { count0++; } if(List->item == 1) { count1++; } if(List->item == 2) { count2++; } if(List->item == 3) { count2++; }if(List->item == 4) { count4++; } } } And here are the errors: error C2065: 'list' : undeclared identifier line 5 error C2062: type 'int' unexpected line 5 error C2661: 'std::list<_Ty>::insert' : no overloaded function takes 1 arguments line 16 error C3861: 'countValue': identifier not found line 21 IntelliSense: no instance of overloaded function "std::list<_Ty, _Ax>::insert [with _Ty=int, _Ax=std::allocator<int>]" matches the argument list line 16 IntelliSense: too few arguments in function call line 16 error C2039: 'item': is not a member of 'std::list<_Ty>' lines 34, 38, 42, 46, 49 IntelliSense: declaration is incompatible with "int countValue" (declared at line 5) line 25 IntelliSense: class "std::list<int, std:: allocator<int>>" has no member "item" lines 34, 38, 42, 46, 49 I just want to know what I've done wrong and how to fix it and also if someone could help me figure out if I'm doing the countValue function wrong or not based on the instructions I would really appreciate it. I've read the chapter in our textbook several times, looked up tutorials on youtube and on Dream in Code, and still I can not figure this out. All helpful information is appreciated!

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  • map with string is broken?[solved]

    - by teritriano
    Yes. I can't see what im doing wrong the map is string, int Here the method bange::function::Add(lua_State *vm){ //userdata, function if (!lua_isfunction(vm, 2)){ cout << "bange: AddFunction: First argument isn't a function." << endl; return false;} void *pfunction = const_cast<void *>(lua_topointer(vm, 2)); char key[32] = {0}; snprintf(key, 32, "%p", pfunction); cout << "Key: " << key << endl; string strkey = key; if (this->functions.find(strkey) != this->functions.end()){ luaL_unref(vm, LUA_REGISTRYINDEX, this->functions[strkey]);} this->functions[strkey] = luaL_ref(vm, LUA_REGISTRYINDEX); return true; Ok, when the code is executed... Program received signal SIGSEGV, Segmentation fault. 0x00007ffff6e6caa9 in std::basic_string<char, std::char_traits<char>, std::allocator<char> > ::compare(std::basic_string<char, std::char_traits<char>, std::allocator<char> > const&) const () from /usr/lib/libstdc++.so.6 Seriously, what's wrong with my code. Thanks for help. Edit 1: Ok, I've done the solution and still fails. I've tried directly insert a string but gives the same error. Let's see, the object is a bange::scene inherited from bange::function. I create the object with lua_newuserdata: bange::scene *scene = static_cast<bange::scene *>(lua_newuserdata(vm, sizeof(bange::scene))); (...) scene = new (scene) bange::scene(width, height, nlayers, vm); I need this for LUA garbage collection. Now the access to bange::function::Add from Lua: static int bangefunction_Add(lua_State *vm){ //userdata, function bange::function *function = reinterpret_cast<bange::function *>(lua_touserdata(vm, 1)); cout &lt&lt "object with bange::function: " &lt&lt function << endl; bool added = function->bange::function::Add(vm); lua_pushboolean(vm, static_cast<int>(added)); return 1; } Userdata is bange::scene stored in Lua. Knowing that userdata is scene, in fact, the object's direction is the same when I've created the scene before. I need the reinterpret_cast, and then call the method. The pointer "this" is still the same direction inside the method. solved I did a small test in the bange::function constructor which works without problems. bange::function::function(){ string test("test"); this->functions["test"] = 2; } I finally noticed that the problem is bange::function *function = reinterpret_cast<bange::function *>(lua_touserdata(vm, 1)); because the object is bange::scene and no bange::function (i admit it, a pointer corruption) and this seems more a code design issue. So this, in a way, is solved. Thanks everybody.

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  • Why is thread local storage so slow?

    - by dsimcha
    I'm working on a custom mark-release style memory allocator for the D programming language that works by allocating from thread-local regions. It seems that the thread local storage bottleneck is causing a huge (~50%) slowdown in allocating memory from these regions compared to an otherwise identical single threaded version of the code, even after designing my code to have only one TLS lookup per allocation/deallocation. This is based on allocating/freeing memory a large number of times in a loop, and I'm trying to figure out if it's an artifact of my benchmarking method. My understanding is that thread local storage should basically just involve accessing something through an extra layer of indirection, similar to accessing a variable via a pointer. Is this incorrect? How much overhead does thread-local storage typically have? Note: Although I mention D, I'm also interested in general answers that aren't specific to D, since D's implementation of thread-local storage will likely improve if it is slower than the best implementations.

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  • Boost interprocess cached pools

    - by porgarmingduod
    I'm trying to figure out if my reading of the docs for boost interprocess allocators is correct. When using cached_adaptive_pool to allocate memory: typedef cached_adaptive_pool<int, managed_shared_memory::segment_manager> pool_allocator_t; pool_allocator_t pool_allocator(segment.get_segment_manager()); // Allocate an integer in the shared memory segment pool_allocator_t::pointer pool_allocator.allocate_one(); My understanding is that with multiple processes one can allocate and deallocate freely: That is, if I have a cached pool allocator for integers in one process, then it can deallocate integers allocated by similar pools in other processes (provided, of course, that they are working on the same shared memory segment). It may be a stupid question, but working with multiple processes and shared memory is hard enough, so I'd like to know 100% whether I got the basics right.

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  • MemSet & MemCopy

    - by pws5068
    I'm writing a memory allocator, and I need a way to store an integer inside of a chunk of memory. This integer will represent the size of the block so I can navigate to the end given the pointer to the beginning. Here's my test example: head_ptr = (char*) malloc(4*1024*1024); // Allocate 4MB memset(head_ptr,12345,sizeof(int)); // Set Address head_ptr = 12345 memcpy(testInt,head_ptr,sizeof(int)); // Set testInt = head_ptr printf("testInt = %i",testInt); This throws a segmentation fault on the second to last line. Does what I'm trying to do make sense? If so, what is the correct approach?

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  • Is it safe to catch an access violation in this scenario?

    - by Eloff
    I've read a lot, including here on SO that suggests this is a very bad idea in general and that the only thing you can do safely is exit the program. I'm not sure that this is true. This is for a pooling memory allocator that hands off large allocations to malloc. During pool_free() a pointer needs to be checked it it belongs to a pool or was allocated with malloc. By rounding the address down to the nearest 1MB boundary, I get a pointer to the beginning of a block of memory in the pool, or undefined if malloc was used. In the first case I can easily verify that the block of memory belongs to the pool, but, if it does not I will either fail this verification, or I will get an access violation (note that this is a read-only process). Could I not catch this with SEH (Windows) or handle the signal (POSIX) and simply treat it as a failed verification? (i.e. this is only possible if malloc was used, so pass the ptr to free())

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  • "Temporary object" warning - is it me or the compiler?

    - by Roddy
    The following snippet gives the warning: [C++ Warning] foo.cpp(70): W8030 Temporary used for parameter '_Val' in call to 'std::vector<Base *,std::allocator<Base *> >::push_back(Base * const &)' .. on the indicated line. class Base { }; class Derived: public Base { public: Derived() // << warning disappears if constructor is removed! { }; }; std::vector<Base*> list1; list1.push_back(new Base); list1.push_back(new Derived); // << Warning on this line! Compiler is Codegear C++Builder 2007. Oddly, if the constructor for Derived is deleted, the warning goes away... Is it me or the compiler?

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  • VMR9Allocator (DirectShow .NET + SlimDX)

    - by faulty
    I was trying to convert and run the VMR9Allocator sample for DirectShow .NET with SlimDX instead of MDX. I got an exception when it reach this line return vmrSurfaceAllocatorNotify.SetD3DDevice(unmanagedDevice, hMonitor) In the AdviseNotify method in Allocator.cs. The exception is "No such interface supported", and the hr return was "0x80004002". The sample runs fine with MDX, and my SlimDx is also working, as I've written another 3d apps using it, working fine. I can't seems to find out what went wrong, no help from googling as well. Apparently not much ppl uses this combination, and non that i can find actually stumble into this problem. Any idea guys? NOTE: I've asked the same question over at gamedev.net 2 weeks back, no answer thus far.

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  • Python json memory bloat

    - by Anoop
    import json import time from itertools import count def keygen(size): for i in count(1): s = str(i) yield '0' * (size - len(s)) + str(s) def jsontest(num): keys = keygen(20) kvjson = json.dumps(dict((keys.next(), '0' * 200) for i in range(num))) kvpairs = json.loads(kvjson) del kvpairs # Not required. Just to check if it makes any difference print 'load completed' jsontest(500000) while 1: time.sleep(1) Linux top indicates that the python process holds ~450Mb of RAM after completion of 'jsontest' function. If the call to 'json.loads' is omitted then this issue is not observed. A gc.collect after this function execution does releases the memory. Looks like the memory is not held in any caches or python's internal memory allocator as explicit call to gc.collect is releasing memory. Is this happening because the threshold for garbage collection (700, 10, 10) was never reached ? I did put some code after jsontest to simulate threshold. But it didn't help.

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  • how to get an instance of an XMLEventAllocator?

    - by kostja
    I am trying to follow the recommended way of parsing XML with StAX using sun's Cursor-to-Event Example for Java EE 5. You are supposed to traverse the XML via the Cursor API and allocate an XMLEventusing an XMLEventAllocator when necessary. Awkwardly, sun's own example does not compile (at least not with JDK 1.6, even with 1.5 code compliance). The example tries to instantiate an allocator via new, but the according implementation classes in the JDK are not accessible externally. After reading the JavaDocs and searching the web I have found literally nothing. One could implement the XMLEventAllocator interface from scratch, but it seems really wrong, when there are perfectly good implementations in the JDK, besides not being an expert in StAX makes it difficult to get it right.

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  • How to intercept deallocate callbacks of Core Foundation objects in Objective-C.

    - by Matteo
    I'm writing an Eiffel wrapper for AppKit and Foundation and I need to hijack all -dealloc methods. Thanks to the dynamic nature of Objective-C it is pretty easy to do that. But the problem is it only works with some of the Foundation or AppKit objects. There are certain objects (e.g. NSString, NSArray, NSDate, ...) that are actually CF objects so the dealloc method doesn't get called. Instead the deallocate callbacks of the allocator that allocated the CF object is called. Is there a way to intercept that?

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  • Resources for memory management in embedded application

    - by Elazar Leibovich
    How should I manage memory in my mission critical embedded application? I found some articles with google, but couldn't pinpoint a really useful practical guide. The DO-178b forbids dynamic memory allocations, but how will you manage the memory than? preallocate everything in advance and send a pointer to each function that needs allocation? Allocate it on the stack? Use a global static allocator (but then it's very similar to dynamic allocation)? Answers can be of the form of regular answer, reference to a resource, or reference to good opensource embedded system for example. clarification: The issue here is not whether or not memory management is availible for the embedded system. But what is a good design for an embedded system, to maximize reliability.

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  • c++ template: 'is not derived from type'

    - by Allan
    I do not understand why this code is not valid: #include <vector> template <typename T> class A{ public: A() { v.clear(); } std::vector<A<T> *>::const_iterator begin(){ return v.begin(); } private: std::vector<A<T> *> v; }; When compiling it with gcc, it get the following error: test.cpp:8: error: type 'std::vector<A<T>*, std::allocator<A<T>*> >' is not derived from type 'A<T>' test.cpp:8: error: expected ';' before 'begin' test.cpp:12: error: expected `;' before 'private' What is wrong, and how to fix it??

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  • C++ String pointers

    - by gnm
    In my previous app I had an object like this: class myType { public: int a; string b; } It had a lot of instances scattered everywhere and passed around to nearly every function. The app was slow. Profiling said that 95% of time is eaten by the string allocator function. I know how to work with the object above, but not how to work with string pointers. class myType { public: int a; string* b; } They told me to use pointers as above. How much faster is it with a string pointer? What is copied when I copy the object? How to the following using the class with the pointer: Access the string value Modify the string value without modifying the one in the object (copy?) General things that change if I use string pointers?

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  • Custom deleters for std::shared_ptrs

    - by Kristian D'Amato
    Is it possible to use a custom deleter after creating a std::shared_ptr without using new? My problem is that object creation is handled by a factory class and its constructors & destructors are protected, which gives a compile error, and I don't want to use new because of its drawbacks. To elaborate: I prefer to create shared pointers like this, which doesn't let you set a custom deleter (I think): auto sp1 = make_shared<Song>(L"The Beatles", L"Im Happy Just to Dance With You"); Or I can create them like this, which does let met set a deleter through an argument: auto sp2(new Song, MyDeleterFunc); But the second one uses new, which AFAIK isn't as efficient as the top sort of allocation. Maybe this is clearer: is it possible to get the benefits of make_shared<> as well as a custom deleter? Would that mean having to write an allocator?

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