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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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  • Why an auto_ptr can "seal" a container

    - by icephere
    auto_ptr on wikipedia said that "an auto_ptr containing an STL container may be used to prevent further modification of the container.". It used the following example: auto_ptr<vector<ContainedType> > open_vec(new vector<ContainedType>); open_vec->push_back(5); open_vec->push_back(3); // Transfers control, but now the vector cannot be changed: auto_ptr<const vector<ContainedType> > closed_vec(open_vec); // closed_vec->push_back(8); // Can no longer modify If I uncomment the last line, g++ will report an error as t05.cpp:24: error: passing ‘const std::vector<int, std::allocator<int> >’ as ‘this’ argument of ‘void std::vector<_Tp, _Alloc>::push_back(const _Tp&) [with _Tp = int, _Alloc = std::allocator<int>]’ discards qualifiers I am curious why after transferring the ownership of this vector, it can no longer be modified? Thanks a lot!

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  • strange redefined symbols

    - by Chris H
    I included this header into one of my own: http://codepad.org/lgJ6KM6b When I compiled I started getting errors like this: CMakeFiles/bin.dir/SoundProjection.cc.o: In function `Gnuplot::reset_plot()': /usr/lib/gcc/x86_64-pc-linux-gnu/4.3.4/include/g++-v4/new:105: multiple definition of `Gnuplot::reset_plot()' CMakeFiles/bin.dir/main.cc.o:project/gnuplot-cpp/gnuplot_i.hpp:962: first defined here CMakeFiles/bin.dir/SoundProjection.cc.o: In function `Gnuplot::set_smooth(std::basic_string, std::allocator const&)': project/gnuplot-cpp/gnuplot_i.hpp:1041: multiple definition of `Gnuplot::set_smooth(std::basic_string, std::allocator const&)' CMakeFiles/bin.dir/main.cc.o:project/gnuplot-cpp/gnuplot_i.hpp:1041: first defined here CMakeFiles/bin.dir/SoundProjection.cc.o:/usr/include/eigen2/Eigen/src/Core/arch/SSE/PacketMath.h:41: multiple definition of `Gnuplot::m_sGNUPlotFileName' I know it's hard to see in this mess, but look at where the redefinitions are taking place. They take place in files like /usr/lib/gcc/x86_64-pc-linux-gnu/4.3.4/include/g++-v4/new:105. How is the new operator getting information about a gnuplot header? I can't even edit that file. How could that ever even be possible? I'm not even sure how to start debugging this. I hope I've provided enough information. I wasn't able to reproduce this in a small project. I mostly just looking for tips on how to find out why this is happening, and how to track it down. Thanks.

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  • CMBufferQueueCreate fail, required parameters?

    - by Agustin
    Reading the documentation about iOS SDK CMBufferQueueCreate, it says that getDuration and version are required, all the others callbacks can be NULL. but running the following code: CFAllocatorRef allocator; CMBufferCallbacks *callbacks; callbacks = malloc(sizeof(CMBufferCallbacks)); callbacks->version = 0; callbacks->getDuration = timeCallback; callbacks->refcon = NULL; callbacks->getDecodeTimeStamp = NULL; callbacks->getPresentationTimeStamp = NULL; callbacks->isDataReady = NULL; callbacks->compare = NULL; callbacks->dataBecameReadyNotification = NULL; CMItemCount capacity = 4; OSStatus s = CMBufferQueueCreate(allocator, capacity, callbacks, queue); NSLog(@"QUEUE: %x", queue); NSLog(@"STATUS: %i", s); with timeCallback: CMTime timeCallback(CMBufferRef buf, void *refcon){ return CMTimeMake(1, 1); } and queue is: CMBufferQueueRef* queue; queue creations fails (queue = 0) and returns a status of: kCMBufferQueueError_RequiredParameterMissing = -12761, The callbacks variable is correctly initialized, at least the debugger says so. Somebody have played arround with CMBufferQueue? google doesn't know about that! Thanks

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  • can't increment Glib::ustring::iterator (getting "invalid lvalue in increment" compiler error)

    - by davka
    in the following code: int utf8len(char* s, int len) { Glib::ustring::iterator p( string::iterator(s) ); Glib::ustring::iterator e ( string::iterator(s+len) ); int i=0; for (; p != e; p++) // ERROR HERE! i++; return i; } I get the compiler error on the for line, which is sometimes "invalid lvalue in increment", and sometimes "ISO C++ forbids incrementing a pointer of type etc... ". Yet, the follwing code: int utf8len(char* s) { Glib::ustring us(s); int i=0; for (Glib::ustring::iterator p = us.begin(); p != us.end(); p++) i++; return i; } compiles and works fine. according the Glib::ustring documentation and the include file, ustring iterator can be constructed from std::string iterator, and has operator++() defined. Weird? BONUS QUESTION :) Is there a difference in C++ between the 2 ways of defining a variable: classname ob1( initval ); classname ob1 = initval; I believed that they are synonymous; yet, if I change Glib::ustring::iterator p( string::iterator(s) ); to Glib::ustring::iterator p = string::iterator(s); I get a compiler error (gcc 4.1.2) conversion from ‘__gnu_cxx::__normal_iterator, std::allocator ’ to non-scalar type ‘Glib::ustring_Iterator<__gnu_cxx::__normal_iterator, std::allocator ’ requesed thanks a lot!

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  • Botan linking error on Windows MSVC

    - by Jake Petroules
    I am trying to compile a library linking to the version of Botan from the Qt Creator sources with MSVC 2008 but am receiving the following error. MinGW compiles and links it fine. What is the issue? databasecrypto.obj:-1: error: LNK2019: unresolved external symbol "public: static unsigned int const Botan::Pipe::DEFAULT_MESSAGE" (?DEFAULT_MESSAGE@Pipe@Botan@@2IB) referenced in function "private: static class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > __cdecl DatabaseCrypto::b64_encode(class Botan::SecureVector<unsigned char> const &)" (?b64_encode@DatabaseCrypto@@CA?AV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@ABV?$SecureVector@E@Botan@@@Z) /*! Encodes the Botan byte array \a in as a base 64 string. \param in The Botan byte array to encode. */ std::string DatabaseCrypto::b64_encode(const SecureVector<Botan::byte> &in) { Pipe pipe(new Base64_Encoder); pipe.process_msg(in); return pipe.read_all_as_string(); // <-- default parameter here is Botan::Pipe::DEFAULT_MESSAGE }

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  • Problem in Building mplsh-run in lshkit

    - by Yijinsei
    Hi guy, been trying out this for quite some time but I'm still unable to built mplsh-run from lshkit Not sure if this would help to explain my situation during the building process /tmp/cc17kth4.o: In function `lshkit::MultiProbeLshRecallTable::reset(lshkit::MultiProbeLshModel, unsigned int, double, double)': mplsh-run.cpp:(.text._ZN6lshkit24MultiProbeLshRecallTable5resetENS_18MultiProbeLshModelEjdd[lshkit::MultiProbeLshRecallTable::reset(lshkit::MultiProbeLshModel, unsigned int, double, double)]+0x230): undefined reference to `lshkit::MultiProbeLshModel::recall(double) const' /tmp/cc17kth4.o: In function `void lshkit::MultiProbeLshIndex<unsigned int>::query_recall<lshkit::TopkScanner<lshkit::Matrix<float>::Accessor, lshkit::metric::l2sqr<float> > >(float const*, float, lshkit::TopkScanner<lshkit::Matrix<float>::Accessor, lshkit::metric::l2sqr<float> >&) const': mplsh-run.cpp:(.text._ZNK6lshkit18MultiProbeLshIndexIjE12query_recallINS_11TopkScannerINS_6MatrixIfE8AccessorENS_6metric5l2sqrIfEEEEEEvPKffRT_[void lshkit::MultiProbeLshIndex<unsigned int>::query_recall<lshkit::TopkScanner<lshkit::Matrix<float>::Accessor, lshkit::metric::l2sqr<float> > >(float const*, float, lshkit::TopkScanner<lshkit::Matrix<float>::Accessor, lshkit::metric::l2sqr<float> >&) const]+0x2c4): undefined reference to `lshkit::MultiProbeLsh::genProbeSequence(float const*, std::vector<unsigned int, std::allocator<unsigned int> >&, unsigned int) const' /tmp/cc17kth4.o: In function `void lshkit::MultiProbeLshIndex<unsigned int>::query<lshkit::TopkScanner<lshkit::Matrix<float>::Accessor, lshkit::metric::l2sqr<float> > >(float const*, unsigned int, lshkit::TopkScanner<lshkit::Matrix<float>::Accessor, lshkit::metric::l2sqr<float> >&)': mplsh-run.cpp:(.text._ZN6lshkit18MultiProbeLshIndexIjE5queryINS_11TopkScannerINS_6MatrixIfE8AccessorENS_6metric5l2sqrIfEEEEEEvPKfjRT_[void lshkit::MultiProbeLshIndex<unsigned int>::query<lshkit::TopkScanner<lshkit::Matrix<float>::Accessor, lshkit::metric::l2sqr<float> > >(float const*, unsigned int, lshkit::TopkScanner<lshkit::Matrix<float>::Accessor, lshkit::metric::l2sqr<float> >&)]+0x4a): undefined reference to `lshkit::MultiProbeLsh::genProbeSequence(float const*, std::vector<unsigned int, std::allocator<unsigned int> >&, unsigned int) const' collect2: ld returned 1 exit status the command that i used to built mplsh-run is g++ -I./lshkit/include -L/usr/lib -lm -lgsl -lgslcblas -lboost_program_options-mt mplsh-run.cpp Do you guys have any clue on how I could solve this?

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  • Compilation errors calling find_if using a functor

    - by Jim Wong
    We are having a bit of trouble using find_if to search a vector of pairs for an entry in which the first element of the pair matches a particular value. To make this work, we have defined a trivial functor whose operator() takes a pair as input and compares the first entry against a string. Unfortunately, when we actually add a call to find_if using an instance of our functor constructed using a temporary string value, the compiler produces a raft of error messages. Oddly (to me, anyway), if we replace the temporary with a string that we've created on the stack, things seem to work. Here's what the code (including both versions) looks like: typedef std::pair<std::string, std::string> MyPair; typedef std::vector<MyPair> MyVector; struct MyFunctor: std::unary_function <const MyPair&, bool> { explicit MyFunctor(const std::string& val) : m_val(val) {} bool operator() (const MyPair& p) { return p.first == m_val; } const std::string m_val; }; bool f(const char* s) { MyFunctor f(std::string(s)); // ERROR // std::string str(s); // MyFunctor f(str); // OK MyVector vec; MyVector::const_iterator i = std::find_if(vec.begin(), vec.end(), f); return i != vec.end(); } And here's what the most interesting error message looks like: /usr/include/c++/4.2.1/bits/stl_algo.h:260: error: conversion from ‘std::pair, std::allocator , std::basic_string, std::allocator ’ to non-scalar type ‘std::string’ requested Because we have a workaround, we're mostly curious as to why the first form causes problems. I'm sure we're missing something, but we haven't been able to figure out what it is.

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  • Intel MKL memory management and exceptions

    - by Andrew
    Hello everyone, I am trying out Intel MKL and it appears that they have their own memory management (C-style). They suggest using their MKL_malloc/MKL_free pairs for vectors and matrices and I do not know what is a good way to handle it. One of the reasons for that is that memory-alignment is recommended to be at least 16-byte and with these routines it is specified explicitly. I used to rely on auto_ptr and boost::smart_ptr a lot to forget about memory clean-ups. How can I write an exception-safe program with MKL memory management or should I just use regular auto_ptr's and not bother? Thanks in advance. EDIT http://software.intel.com/sites/products/documentation/hpc/mkl/win/index.htm this link may explain why I brought up the question UPDATE I used an idea from the answer below for allocator. This is what I have now: template <typename T, size_t TALIGN=16, size_t TBLOCK=4> class aligned_allocator : public std::allocator<T> { public: pointer allocate(size_type n, const void *hint) { pointer p = NULL; size_t count = sizeof(T) * n; size_t count_left = count % TBLOCK; if( count_left != 0 ) count += TBLOCK - count_left; if ( !hint ) p = reinterpret_cast<pointer>(MKL_malloc (count,TALIGN)); else p = reinterpret_cast<pointer>(MKL_realloc((void*)hint,count,TALIGN)); return p; } void deallocate(pointer p, size_type n){ MKL_free(p); } }; If anybody has any suggestions, feel free to make it better.

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  • Duplicate Symbol Linker Error (C++ help)

    - by Vash265
    Hi. I'm learning some CSP (constraint satisfaction) theory stuff right now, and am using this library to parse XML files. I'm using Xcode as an IDE. My program compiles fine, but when it goes to link the files, I get a duplicate symbol error with the XMLParser_libxml2.hh file. My files are separated as such: A class header file that includes the XMLParser file above A class implementation file that include the class header file A main file that includes the class header file The duplicate symbol is occurring in main.o and classfile.o, but as far as I can tell, I'm not actually adding that .hh file twice. Full error: ld: duplicate symbol bool CSPXMLParser::UTF8String::to<std::basic_string<char, std::char_traits<char>, std::allocator<char> > >(std::basic_string<char, std::char_traits<char>, std::allocator<char> >&) constin /Users/vash265/CSP/Untitled/build/Untitled.build/Debug/Untitled.build/Objects-normal/x86_64/dStructFill.o and /Users/vash265/CSP/Untitled/build/Untitled.build/Debug/Untitled.build/Objects-normal/x86_64/main.o Copying the implementation of the class into the main file and taking the class implementation file out of the compilation target alleviates the error, but it's a disorganized mess this way, and I'll be adding more classes very soon (and it would be nice to have them in separate files). As I've come to understand it, this is caused by the file (XMLParser_libxml2.hh) having both the class and function definition and implementation in one file (and it seems as though this might have been necessary due to the use of templates in that 'header' file). Any ideas on how to get around sticking all my class files in my main.cpp? (I've tried ifdefs, they don't work).

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  • Linking a template class using another template class (error LNK2001)

    - by Luís Guilherme
    I implemented the "Strategy" design pattern using an Abstract template class, and two subclasses. Goes like this: template <class T> class Neighbourhood { public: virtual void alter(std::vector<T>& array, int i1, int i2) = 0; }; and template <class T> class Swap : public Neighbourhood<T> { public: virtual void alter(std::vector<T>& array, int i1, int i2); }; There's another subclass, just like this one, and alter is implemented in the cpp file. Ok, fine! Now I declare another method, in another class (including neighbourhood header file, of course), like this: void lSearch(/*parameters*/, Neighbourhood<LotSolutionInformation> nhood); It compiles fine and cleanly. When starting to link, I get the following error: 1>SolverFV.obj : error LNK2001: unresolved external symbol "public: virtual void __thiscall lsc::Neighbourhood<class LotSolutionInformation>::alter(class std::vector<class LotSolutionInformation,class std::allocator<class LotSolutionInformation> > &,int,int)" (?alter@?$Neighbourhood@VLotSolutionInformation@@@lsc@@UAEXAAV?$vector@VLotSolutionInformation@@V?$allocator@VLotSolutionInformation@@@std@@@std@@HH@Z)

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  • "Forced constness" in std::map<std::vector<int>,double> > ?

    - by Peter Jansson
    Consider this program: #include <map> #include <vector> typedef std::vector<int> IntVector; typedef std::map<IntVector,double> Map; void foo(Map& m,const IntVector& v) { Map::iterator i = m.find(v); i->first.push_back(10); }; int main() { Map m; IntVector v(10,10); foo(m,v); return 0; } Using g++ 4.4.0, I get his compilation error: test.cpp: In function 'void foo(Map&, const IntVector&)': test.cpp:8: error: passing 'const std::vector<int, std::allocator<int> >' as 'this' argument of 'void std::vector<_Tp, _Alloc>::push_back(const _Tp&) [with _Tp = int, _Alloc = std::allocator<int>]' discards qualifiers I would expect this error if I was using Map::const_iterator inside foo but not using a non-const iterator. What am I missing, why do I get this error?

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  • Information about PTE's (Page Table Entries) in Windows

    - by Patrick
    In order to find more easily buffer overflows I am changing our custom memory allocator so that it allocates a full 4KB page instead of only the wanted number of bytes. Then I change the page protection and size so that if the caller writes before or after its allocated piece of memory, the application immediately crashes. Problem is that although I have enough memory, the application never starts up completely because it runs out of memory. This has two causes: since every allocation needs 4 KB, we probably reach the 2 GB limit very soon. This problem could be solved if I would make a 64-bit executable (didn't try it yet). even when I only need a few hundreds of megabytes, the allocations fail at a certain moment. The second problem is the biggest one, and I think it's related to the maximum number of PTE's (page table entries, which store information on how Virtual Memory is mapped to physical memory, and whether pages should be read-only or not) you can have in a process. My questions (or a cry-for-tips): Where can I find information about the maximum number of PTE's in a process? Is this different (higher) for 64-bit systems/applications or not? Can the number of PTE's be configured in the application or in Windows? Thanks, Patrick PS. note for those who will try to argument that you shouldn't write your own memory manager: My application is rather specific so I really want full control over memory management (can't give any more details) Last week we had a memory overwrite which we couldn't find using the standard C++ allocator and the debugging functionality of the C/C++ run time (it only said "block corrupt" minutes after the actual corruption") We also tried standard Windows utilities (like GFLAGS, ...) but they slowed down the application by a factor of 100, and couldn't find the exact position of the overwrite either We also tried the "Full Page Heap" functionality of Application Verifier, but then the application doesn't start up either (probably also running out of PTE's)

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  • c++ overloading delete, retrieve size

    - by user300713
    Hi, I am currently writing a small custom memory Allocator in c++, and want to use it together with operator overloading of new/delete. Anyways, my memory Allocator basicall checks if the requested memory is over a certain threshold, and if so uses malloc to allocate the requested memory chunk. Otherwise the memory will be provided by some fixedPool allocators. that generally works, but for my deallocation function looks like this: void MemoryManager::deallocate(void * _ptr, size_t _size){ if(_size heapThreshold) deallocHeap(_ptr); else deallocFixedPool(_ptr, _size); } so I need to provide the size of the chunk pointed to, to deallocate from the right place. No the problem is that the delete keyword does not provide any hint on the size of the deleted chunk, so I would need something like this: void operator delete(void * _ptr, size_t _size){ MemoryManager::deallocate(_ptr, _size); } But as far as I can see, there is no way to determine the size inside the delete operator.- If I want to keep things the way it is right now, would I have to save the size of the memory chunks myself? Any ideas on how to solve this are welcome! Thanks!

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  • Why doesn't String's hashCode() cache 0?

    - by polygenelubricants
    I noticed in the Java 6 source code for String that hashCode only caches values other than 0. The difference in performance is exhibited by the following snippet: public class Main{ static void test(String s) { long start = System.currentTimeMillis(); for (int i = 0; i < 10000000; i++) { s.hashCode(); } System.out.format("Took %d ms.%n", System.currentTimeMillis() - start); } public static void main(String[] args) { String z = "Allocator redistricts; strict allocator redistricts strictly."; test(z); test(z.toUpperCase()); } } Running this in ideone.com gives the following output: Took 1470 ms. Took 58 ms. So my questions are: Why doesn't String's hashCode() cache 0? What is the probability that a Java string hashes to 0? What's the best way to avoid the performance penalty of recomputing the hash value every time for strings that hash to 0? Is this the best-practice way of caching values? (i.e. cache all except one?) For your amusement, each line here is a string that hash to 0: pollinating sandboxes amusement & hemophilias schoolworks = perversive electrolysissweeteners.net constitutionalunstableness.net grinnerslaphappier.org BLEACHINGFEMININELY.NET WWW.BUMRACEGOERS.ORG WWW.RACCOONPRUDENTIALS.NET Microcomputers: the unredeemed lollipop... Incentively, my dear, I don't tessellate a derangement. A person who never yodelled an apology, never preened vocalizing transsexuals.

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  • C++ STL question related to insert iterators and overloaded operators

    - by rshepherd
    #include <list> #include <set> #include <iterator> #include <algorithm> using namespace std; class MyContainer { public: string value; MyContainer& operator=(const string& s) { this->value = s; return *this; } }; int main() { list<string> strings; strings.push_back("0"); strings.push_back("1"); strings.push_back("2"); set<MyContainer> containers; copy(strings.begin(), strings.end(), inserter(containers, containers.end())); } The preceeding code does not compile. In standard C++ fashion the error output is verbose and difficult to understand. The key part seems to be this... /usr/include/c++/4.4/bits/stl_algobase.h:313: error: no match for ‘operator=’ in ‘__result.std::insert_iterator::operator* [with _Container = std::set, std::allocator ]() = __first.std::_List_iterator::operator* [with _Tp = std::basic_string, std::allocator ]()’ ...which I interpet to mean that the assignment operator needed is not defined. I took a look at the source code for insert_iterator and noted that it has overloaded the assignment operator. The copy algorithm must uses the insert iterators overloaded assignment operator to do its work(?). I guess that because my input iterator is on a container of strings and my output iterator is on a container of MyContainers that the overloaded insert_iterator assignment operator can no longer work. This is my best guess, but I am probably wrong. So, why exactly does this not work and how can I accomplish what I am trying to do?

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  • C++ new memory allocation fragmentation

    - by tamulj
    I was trying to look at the behavior of the new allocator and why it doesn't place data contiguously. My code: struct ci { char c; int i; } template <typename T> void memTest() { T * pLast = new T(); for(int i = 0; i < 20; ++i) { T * pNew = new T(); cout << (pNew - pLast) << " "; pLast = pNew; } } So I ran this with char, int, ci. Most allocations were a fixed length from the last, sometimes there were odd jumps from one available block to another. sizeof(char) : 1 Average Jump: 64 bytes sizeof(int): 4 Average Jump: 16 sizeof(ci): 8 (int has to be placed on a 4 byte align) Average Jump: 9 Can anyone explain why the allocator is fragmenting memory like this? Also why is the jump for char so much larger then ints and a structure that contains both an int and char.

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  • C++ STL question related to insert iterators and sets

    - by rshepherd
    #include #include #include #include using namespace std; class MyContainer { public: string value; MyContainer& operator=(const string& s) { this->value = s; return *this; } }; int main() { list<string> strings; strings.push_back("0"); strings.push_back("1"); strings.push_back("2"); set<MyContainer> containers; copy(strings.begin(), strings.end(), inserter(containers, containers.end())); } The preceeding code does not compile. In typical STL style the error output is verbose and difficult to understand. The key part seems to be this... /usr/include/c++/4.4/bits/stl_algobase.h:313: error: no match for ‘operator=’ in ‘__result.std::insert_iterator::operator* [with _Container = std::set, std::allocator ]() = __first.std::_List_iterator::operator* [with _Tp = std::basic_string, std::allocator ]()’ ...which I interpet to mean that the assignment operator needed is not defined. I took a look at the source code for insert_iterator and noted that it has overloaded the assignment operator. The copy algorithm must uses the insert iterators overloaded assignment operator to do its work(?). I guess that because my input iterator is on a container of strings and my output iterator is on a container of MyContainers that the overloaded insert_iterator assignment operator can no longer work. This is my best guess, but I am probably wrong. So, why exactly does this not work and how can I accomplish what I am trying to do?

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  • How Microsoft Lost the API War - by Joel Spolsky

    - by TechTwaddle
    Came across another gem of an article by Joel Spolsky. It's a pretty old article written in June of 2004, has lot of tidbits and I really enjoyed reading it, so much in fact that I read it twice! So hit the link below and give it a read if you haven't already, How Microsoft Lost the API War - Joel Spolsky excerpt, "I first heard about this from one of the developers of the hit game SimCity, who told me that there was a critical bug in his application: it used memory right after freeing it, a major no-no that happened to work OK on DOS but would not work under Windows where memory that is freed is likely to be snatched up by another running application right away. The testers on the Windows team were going through various popular applications, testing them to make sure they worked OK, but SimCity kept crashing. They reported this to the Windows developers, who disassembled SimCity, stepped through it in a debugger, found the bug, and added special code that checked if SimCity was running, and if it did, ran the memory allocator in a special mode in which you could still use memory after freeing it."

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  • Profiling and containing memory per system

    - by chadb
    I have been interesting in profiling and keeping a managed memory pool for each subsystem, so I could get statistic on how much memory was being used in something such as sounds or graphics. However, what is the best design for doing this? I was thinking of using multiple allocators and just using one per subsystem, however, that would result in global variables for my allocators (or so it would seem to me). Another approach I have seen/been suggested is to just overload new and pass in an allocator for a parameter. I had a similar question over on stackoverflow here with a bounty, however, it seems as if perhaps I was too vague or just there is not enough people with knowledge in the subject.

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  • Error compiling / linking e text editor on Linux

    - by jckdnk111
    The code compiles without too much complaint, but the last step fails with the error below. There is some discussion about it on the e forum, but still no answer. [LD] e ../external/out.release/lib/libpcre.a(pcre_tables.o):(.rodata+0x0): multiple definition of `_pcre_OP_lengths' .objs.release/cx_pcre_tables.o:(.rodata+0x0): first defined here ../external/out.release/lib/libpcre.a(pcre_tables.o):(.rodata+0x70): multiple definition of `_pcre_utf8_table1' .objs.release/cx_pcre_tables.o:(.rodata+0x70): first defined here ../external/out.release/lib/libpcre.a(pcre_tables.o):(.rodata+0x88): multiple definition of `_pcre_utf8_table1_size' .objs.release/cx_pcre_tables.o:(.rodata+0x88): first defined here ../external/out.release/lib/libpcre.a(pcre_tables.o):(.rodata+0x8c): multiple definition of `_pcre_utf8_table2' .objs.release/cx_pcre_tables.o:(.rodata+0x8c): first defined here ../external/out.release/lib/libpcre.a(pcre_tables.o):(.rodata+0xa4): multiple definition of `_pcre_utf8_table3' .objs.release/cx_pcre_tables.o:(.rodata+0xa4): first defined here ../external/out.release/lib/libpcre.a(pcre_tables.o):(.rodata+0xc0): multiple definition of `_pcre_utf8_table4' .objs.release/cx_pcre_tables.o:(.rodata+0xc0): first defined here ../external/out.release/lib/libpcre.a(pcre_tables.o):(.rodata+0x180): multiple definition of `_pcre_utt_names' .objs.release/cx_pcre_tables.o:(.rodata+0x100): first defined here /usr/bin/ld: Warning: size of symbol `_pcre_utt_names' changed from 657 in .objs.release/cx_pcre_tables.o to 740 in ../external/out.release/lib/libpcre.a(pcre_tables.o) ../external/out.release/lib/libpcre.a(pcre_tables.o):(.rodata+0x480): multiple definition of `_pcre_utt' .objs.release/cx_pcre_tables.o:(.rodata+0x3a0): first defined here /usr/bin/ld: Warning: size of symbol `_pcre_utt' changed from 630 in .objs.release/cx_pcre_tables.o to 696 in ../external/out.release/lib/libpcre.a(pcre_tables.o) ../external/out.release/lib/libpcre.a(pcre_tables.o):(.rodata+0x738): multiple definition of `_pcre_utt_size' .objs.release/cx_pcre_tables.o:(.rodata+0x618): first defined here .objs.release/cx_pcre_exec.o: In function `match(doc_byte_iter, unsigned char const*, doc_byte_iter, int, match_data*, unsigned long, eptrblock*, int, unsigned int)': cx_pcre_exec.cpp:(.text+0x1c2a): undefined reference to `_pcre_ord2utf8(int, unsigned char*)' .objs.release/eauibook.o: In function `eAuiNotebook::LoadPerspective(wxString const&)': eauibook.cpp:(.text+0x9ad): undefined reference to `wxTabFrame::SetTabCtrlHeight(int)' .objs.release/PreviewDlg.o: In function `global constructors keyed to _ZN10PreviewDlg13sm_eventTableE': PreviewDlg.cpp:(.text+0x11b2): undefined reference to `wxEVT_WEB_TITLECHANGE' PreviewDlg.cpp:(.text+0x11ee): undefined reference to `wxEVT_WEB_DOMCONTENTLOADED' .objs.release/PreviewDlg.o: In function `PreviewDlg::RefreshBrowser(PreviewDlg::cxUpdateMode)': PreviewDlg.cpp:(.text+0x2a47): undefined reference to `wxWebControl::OpenURI(wxString const&, unsigned int, wxWebPostData*, bool)' .objs.release/PreviewDlg.o: In function `PreviewDlg::OnWebDocumentComplete(wxWebEvent&)': PreviewDlg.cpp:(.text+0x3259): undefined reference to `wxWebControl::GetCurrentURI() const' .objs.release/PreviewDlg.o: In function `PreviewDlg::PreviewDlg(EditorFrame&)': PreviewDlg.cpp:(.text+0x4984): undefined reference to `wxWebControl::IsInitialized()' PreviewDlg.cpp:(.text+0x49c5): undefined reference to `wxWebControl::wxWebControl(wxWindow*, int, wxPoint const&, wxSize const&)' PreviewDlg.cpp:(.text+0x562f): undefined reference to `wxWebControl::InitEngine(wxString const&)' .objs.release/PreviewDlg.o: In function `PreviewDlg::PreviewDlg(EditorFrame&)': PreviewDlg.cpp:(.text+0x68e4): undefined reference to `wxWebControl::IsInitialized()' PreviewDlg.cpp:(.text+0x6925): undefined reference to `wxWebControl::wxWebControl(wxWindow*, int, wxPoint const&, wxSize const&)' PreviewDlg.cpp:(.text+0x758f): undefined reference to `wxWebControl::InitEngine(wxString const&)' .objs.release/PreviewDlg.o: In function `PreviewDlg::OnButtonForward(wxCommandEvent&)': PreviewDlg.cpp:(.text+0x132): undefined reference to `wxWebControl::GoForward()' .objs.release/PreviewDlg.o: In function `PreviewDlg::OnButtonBack(wxCommandEvent&)': PreviewDlg.cpp:(.text+0x182): undefined reference to `wxWebControl::GoBack()' ../ecore/libecore.so(cxInternal.o): In function `cxInternal::MoveOldSettings(eSettings&)': cxInternal.cpp:(.text+0x4d29): undefined reference to `eSettings::SetPageSettings(unsigned int, wxString const&, doc_id, int, int, wxString const&, std::vector<unsigned int, std::allocator<unsigned int> > const&, std::vector<cxBookmark, std::allocator<cxBookmark> > const&, eSettings::SubPage)' collect2: ld returned 1 exit status make: *** [e] Error 1 EDIT: Forgot the link http://github.com/etexteditor/e

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  • Template inheritence c++

    - by Chris Condy
    I have made a template singleton class, I have also made a data structure that is templated. My question is; how do I make my templated data structure inherit from a singleton so you can only have one float type of this structure? I have tested both seperate and have found no problems. Code provided under... (That is the problem) template <class Type> class AbstractRManagers : public Singleton<AbstractRManagers<Type> > The problem is the code above doesn't work I get alot of errors. I cant get it to no matter what I do template a templated singleton class... I was asking for maybe advice or maybe if the code above is incorrect guidence? #ifndef SINGLETON_H #define SINGLETON_H template <class Type> class Singleton { public: virtual ~Singleton(); Singleton(); static Type* m_instance; }; template <class Type> Type* Singleton<Type>::m_instance = 0; #include "Singleton.cpp" #endif #ifndef SINGLETON_CPP #define SINGLETON_CPP #include "Singleton.h" template <class Type> Singleton<Type>::Singleton() { } template <class Type> Singleton<Type>::~Singleton() { } template <class Type> Type* Singleton<Type>::getInstance() { if(m_instance==nullptr) { m_instance = new Type; } return m_instance; } #endif #ifndef ABSTRACTRMANAGERS_H #define ABSTRACTRMANAGERS_H #include <vector> #include <map> #include <stack> #include "Singleton.h" template <class Type> class AbstractRManagers : public Singleton<AbstractRManagers<Type> > { public: virtual ~AbstractRManagers(); int insert(Type* type, std::string name); Type* remove(int i); Type* remove(std::string name); Type* get(int i); Type* getS(std::string name); int get(std::string name); int get(Type* i); bool check(std::string name); int resourceSize(); protected: private: std::vector<Type*> m_resources; std::map<std::string,int> m_map; std::stack<int> m_freePos; }; #include "AbstractRManagers.cpp" #endif #ifndef ABSTRACTRMANAGERS_CPP #define ABSTRACTRMANAGERS_CPP #include "AbstractRManagers.h" template <class Type> int AbstractRManagers<Type>::insert(Type* type, std::string name) { int i=0; if(!check(name)) { if(m_freePos.empty()) { m_resources.push_back(type); i = m_resources.size()-1; m_map[name] = i; } else { i = m_freePos.top(); m_freePos.pop(); m_resources[i] = type; m_map[name] = i; } } else i = -1; return i; } template <class Type> int AbstractRManagers<Type>::resourceSize() { return m_resources.size(); } template <class Type> bool AbstractRManagers<Type>::check(std::string name) { std::map<std::string,int>::iterator it; it = m_map.find(name); if(it==m_map.end()) return false; return true; } template <class Type> Type* AbstractRManagers<Type>::remove(std::string name) { Type* temp = m_resources[m_map[name]]; if(temp!=NULL) { std::map<std::string,int>::iterator it; it = m_map[name]; m_resources[m_map[name]] = NULL; m_freePos.push(m_map[name]); delete (*it).second; delete (*it).first; return temp; } return NULL; } template <class Type> Type* AbstractRManagers<Type>::remove(int i) { if((i < m_resources.size())&&(i > 0)) { Type* temp = m_resources[i]; m_resources[i] = NULL; m_freePos.push(i); std::map<std::string,int>::iterator it; for(it=m_map.begin();it!=m_map.end();it++) { if((*it).second == i) { delete (*it).second; delete (*it).first; return temp; } } return temp; } return NULL; } template <class Type> int AbstractRManagers<Type>::get(Type* i) { for(int i2=0;i2<m_resources.size();i2++) { if(i == m_resources[i2]) { return i2; } } return -1; } template <class Type> Type* AbstractRManagers<Type>::get(int i) { if((i < m_resources.size())&&(i >= 0)) { return m_resources[i]; } return NULL; } template <class Type> Type* AbstractRManagers<Type>::getS(std::string name) { return m_resources[m_map[name]]; } template <class Type> int AbstractRManagers<Type>::get(std::string name) { return m_map[name]; } template <class Type> AbstractRManagers<Type>::~AbstractRManagers() { } #endif #include "AbstractRManagers.h" struct b { float x; }; int main() { b* a = new b(); AbstractRManagers<b>::getInstance()->insert(a,"a"); return 0; } This program produces next errors when compiled : 1> main.cpp 1>c:\program files\microsoft visual studio 10.0\vc\include\xfunctional(125): error C2784: 'bool std::operator <(const std::stack<_Ty,_Container> &,const std::stack<_Ty,_Container> &)' : could not deduce template argument for 'const std::stack<_Ty,_Container> &' from 'const std::string' 1> c:\program files\microsoft visual studio 10.0\vc\include\stack(166) : see declaration of 'std::operator <' 1> c:\program files\microsoft visual studio 10.0\vc\include\xfunctional(124) : while compiling class template member function 'bool std::less<_Ty>::operator ()(const _Ty &,const _Ty &) const' 1> with 1> [ 1> _Ty=std::string 1> ] 1> c:\program files\microsoft visual studio 10.0\vc\include\map(71) : see reference to class template instantiation 'std::less<_Ty>' being compiled 1> with 1> [ 1> _Ty=std::string 1> ] 1> c:\program files\microsoft visual studio 10.0\vc\include\xtree(451) : see reference to class template instantiation 'std::_Tmap_traits<_Kty,_Ty,_Pr,_Alloc,_Mfl>' being compiled 1> with 1> [ 1> _Kty=std::string, 1> _Ty=int, 1> _Pr=std::less<std::string>, 1> _Alloc=std::allocator<std::pair<const std::string,int>>, 1> _Mfl=false 1> ] 1> c:\program files\microsoft visual studio 10.0\vc\include\xtree(520) : see reference to class template instantiation 'std::_Tree_nod<_Traits>' being compiled 1> with 1> [ 1> _Traits=std::_Tmap_traits<std::string,int,std::less<std::string>,std::allocator<std::pair<const std::string,int>>,false> 1> ] 1> c:\program files\microsoft visual studio 10.0\vc\include\xtree(659) : see reference to class template instantiation 'std::_Tree_val<_Traits>' being compiled 1> with 1> [ 1> _Traits=std::_Tmap_traits<std::string,int,std::less<std::string>,std::allocator<std::pair<const std::string,int>>,false> 1> ] 1> c:\program files\microsoft visual studio 10.0\vc\include\map(81) : see reference to class template instantiation 'std::_Tree<_Traits>' being compiled 1> with 1> [ 1> _Traits=std::_Tmap_traits<std::string,int,std::less<std::string>,std::allocator<std::pair<const std::string,int>>,false> 1> ] 1> c:\users\chris\desktop\311\ideas\idea1\idea1\abstractrmanagers.h(28) : see reference to class template instantiation 'std::map<_Kty,_Ty>' being compiled 1> with 1> [ 1> _Kty=std::string, 1> _Ty=int 1> ] 1> c:\users\chris\desktop\311\ideas\idea1\idea1\abstractrmanagers.h(30) : see reference to class template instantiation 'AbstractRManagers<Type>' being compiled 1>c:\program files\microsoft visual studio 10.0\vc\include\xfunctional(125): error C2784: 'bool std::operator <(const std::stack<_Ty,_Container> &,const std::stack<_Ty,_Container> &)' : could not deduce template argument for 'const std::stack<_Ty,_Container> &' from 'const std::string' 1> c:\program files\microsoft visual studio 10.0\vc\include\stack(166) : see declaration of 'std::operator <' 1>c:\program files\microsoft visual studio 10.0\vc\include\xfunctional(125): error C2784: 'bool std::operator <(const std::stack<_Ty,_Container> &,const std::stack<_Ty,_Container> &)' : could not deduce template argument for 'const std::stack<_Ty,_Container> &' from 'const std::string' 1> c:\program files\microsoft visual studio 10.0\vc\include\stack(166) : see declaration of 'std::operator <' 1>c:\program files\microsoft visual studio 10.0\vc\include\xfunctional(125): error C2784: 'bool std::operator <(const std::deque<_Ty,_Alloc> &,const std::deque<_Ty,_Alloc> &)' : could not deduce template argument for 'const std::deque<_Ty,_Alloc> &' from 'const std::string' 1> c:\program files\microsoft visual studio 10.0\vc\include\deque(1725) : see declaration of 'std::operator <' 1>c:\program files\microsoft visual studio 10.0\vc\include\xfunctional(125): error C2784: 'bool std::operator <(const std::deque<_Ty,_Alloc> &,const std::deque<_Ty,_Alloc> &)' : could not deduce template argument for 'const std::deque<_Ty,_Alloc> &' from 'const std::string' 1> c:\program files\microsoft visual studio 10.0\vc\include\deque(1725) : see declaration of 'std::operator <' 1>c:\program files\microsoft visual studio 10.0\vc\include\xfunctional(125): error C2784: 'bool std::operator <(const std::deque<_Ty,_Alloc> &,const std::deque<_Ty,_Alloc> &)' : could not deduce template argument for 'const std::deque<_Ty,_Alloc> &' from 'const std::string' 1> c:\program files\microsoft visual studio 10.0\vc\include\deque(1725) : see declaration of 'std::operator <' 1>c:\program files\microsoft visual studio 10.0\vc\include\xfunctional(125): error C2784: 'bool std::operator <(const std::_Tree<_Traits> &,const std::_Tree<_Traits> &)' : could not deduce template argument for 'const std::_Tree<_Traits> &' from 'const std::string' 1> c:\program files\microsoft visual studio 10.0\vc\include\xtree(1885) : see declaration of 'std::operator <' 1>c:\program files\microsoft visual studio 10.0\vc\include\xfunctional(125): error C2784: 'bool std::operator <(const std::_Tree<_Traits> &,const std::_Tree<_Traits> &)' : could not deduce template argument for 'const std::_Tree<_Traits> &' from 'const std::string' 1> c:\program files\microsoft visual studio 10.0\vc\include\xtree(1885) : see declaration of 'std::operator <' 1>c:\program files\microsoft visual studio 10.0\vc\include\xfunctional(125): error C2784: 'bool std::operator <(const std::_Tree<_Traits> &,const std::_Tree<_Traits> &)' : could not deduce template argument for 'const std::_Tree<_Traits> &' from 'const std::string' 1> c:\program files\microsoft visual studio 10.0\vc\include\xtree(1885) : see declaration of 'std::operator <' 1>c:\program files\microsoft visual studio 10.0\vc\include\xfunctional(125): error C2784: 'bool std::operator <(const std::vector<_Ty,_Ax> &,const std::vector<_Ty,_Ax> &)' : could not deduce template argument for 'const std::vector<_Ty,_Ax> &' from 'const std::string' 1> c:\program files\microsoft visual studio 10.0\vc\include\vector(1502) : see declaration of 'std::operator <' 1>c:\program files\microsoft visual studio 10.0\vc\include\xfunctional(125): error C2784: 'bool std::operator <(const std::vector<_Ty,_Ax> &,const std::vector<_Ty,_Ax> &)' : could not deduce template argument for 'const std::vector<_Ty,_Ax> &' from 'const std::string' 1> c:\program files\microsoft visual studio 10.0\vc\include\vector(1502) : see declaration of 'std::operator <' 1>c:\program files\microsoft visual studio 10.0\vc\include\xfunctional(125): error C2784: 'bool std::operator <(const std::vector<_Ty,_Ax> &,const std::vector<_Ty,_Ax> &)' : could not deduce template argument for 'const std::vector<_Ty,_Ax> &' from 'const std::string' 1> c:\program files\microsoft visual studio 10.0\vc\include\vector(1502) : see declaration of 'std::operator <' 1>c:\program files\microsoft visual studio 10.0\vc\include\xfunctional(125): error C2784: 'bool std::operator <(const std::unique_ptr<_Ty,_Dx> &,const std::unique_ptr<_Ty2,_Dx2> &)' : could not deduce template argument for 'const std::unique_ptr<_Ty,_Dx> &' from 'const std::string' 1> c:\program files\microsoft visual studio 10.0\vc\include\memory(2582) : see declaration of 'std::operator <' 1>c:\program files\microsoft visual studio 10.0\vc\include\xfunctional(125): error C2784: 'bool std::operator <(const std::unique_ptr<_Ty,_Dx> &,const std::unique_ptr<_Ty2,_Dx2> &)' : could not deduce template argument for 'const std::unique_ptr<_Ty,_Dx> &' from 'const std::string' 1> c:\program files\microsoft visual studio 10.0\vc\include\memory(2582) : see declaration of 'std::operator <' 1>c:\program files\microsoft visual studio 10.0\vc\include\xfunctional(125): error C2784: 'bool std::operator <(const std::unique_ptr<_Ty,_Dx> &,const std::unique_ptr<_Ty2,_Dx2> &)' : could not deduce template argument for 'const std::unique_ptr<_Ty,_Dx> &' from 'const std::string' 1> c:\program files\microsoft visual studio 10.0\vc\include\memory(2582) : see declaration of 'std::operator <' 1>c:\program files\microsoft visual studio 10.0\vc\include\xfunctional(125): error C2784: 'bool std::operator <(const std::reverse_iterator<_RanIt> &,const std::reverse_iterator<_RanIt2> &)' : could not deduce template argument for 'const std::reverse_iterator<_RanIt> &' from 'const std::string' 1> c:\program files\microsoft visual studio 10.0\vc\include\xutility(1356) : see declaration of 'std::operator <' 1>c:\program files\microsoft visual studio 10.0\vc\include\xfunctional(125): error C2784: 'bool std::operator <(const std::reverse_iterator<_RanIt> &,const std::reverse_iterator<_RanIt2> &)' : could not deduce template argument for 'const std::reverse_iterator<_RanIt> &' from 'const std::string' 1> c:\program files\microsoft visual studio 10.0\vc\include\xutility(1356) : see declaration of 'std::operator <' 1>c:\program files\microsoft visual studio 10.0\vc\include\xfunctional(125): error C2784: 'bool std::operator <(const std::reverse_iterator<_RanIt> &,const std::reverse_iterator<_RanIt2> &)' : could not deduce template argument for 'const std::reverse_iterator<_RanIt> &' from 'const std::string' 1> c:\program files\microsoft visual studio 10.0\vc\include\xutility(1356) : see declaration of 'std::operator <' 1>c:\program files\microsoft visual studio 10.0\vc\include\xfunctional(125): error C2784: 'bool std::operator <(const std::_Revranit<_RanIt,_Base> &,const std::_Revranit<_RanIt2,_Base2> &)' : could not deduce template argument for 'const std::_Revranit<_RanIt,_Base> &' from 'const std::string' 1> c:\program files\microsoft visual studio 10.0\vc\include\xutility(1179) : see declaration of 'std::operator <' 1>c:\program files\microsoft visual studio 10.0\vc\include\xfunctional(125): error C2784: 'bool std::operator <(const std::_Revranit<_RanIt,_Base> &,const std::_Revranit<_RanIt2,_Base2> &)' : could not deduce template argument for 'const std::_Revranit<_RanIt,_Base> &' from 'const std::string' 1> c:\program files\microsoft visual studio 10.0\vc\include\xutility(1179) : see declaration of 'std::operator <' 1>c:\program files\microsoft visual studio 10.0\vc\include\xfunctional(125): error C2784: 'bool std::operator <(const std::_Revranit<_RanIt,_Base> &,const std::_Revranit<_RanIt2,_Base2> &)' : could not deduce template argument for 'const std::_Revranit<_RanIt,_Base> &' from 'const std::string' 1> c:\program files\microsoft visual studio 10.0\vc\include\xutility(1179) : see declaration of 'std::operator <' 1>c:\program files\microsoft visual studio 10.0\vc\include\xfunctional(125): error C2784: 'bool std::operator <(const std::pair<_Ty1,_Ty2> &,const std::pair<_Ty1,_Ty2> &)' : could not deduce template argument for 'const std::pair<_Ty1,_Ty2> &' from 'const std::string' 1> c:\program files\microsoft visual studio 10.0\vc\include\utility(318) : see declaration of 'std::operator <' 1>c:\program files\microsoft visual studio 10.0\vc\include\xfunctional(125): error C2784: 'bool std::operator <(const std::pair<_Ty1,_Ty2> &,const std::pair<_Ty1,_Ty2> &)' : could not deduce template argument for 'const std::pair<_Ty1,_Ty2> &' from 'const std::string' 1> c:\program files\microsoft visual studio 10.0\vc\include\utility(318) : see declaration of 'std::operator <' 1>c:\program files\microsoft visual studio 10.0\vc\include\xfunctional(125): error C2784: 'bool std::operator <(const std::pair<_Ty1,_Ty2> &,const std::pair<_Ty1,_Ty2> &)' : could not deduce template argument for 'const std::pair<_Ty1,_Ty2> &' from 'const std::string' 1> c:\program files\microsoft visual studio 10.0\vc\include\utility(318) : see declaration of 'std::operator <' 1>c:\program files\microsoft visual studio 10.0\vc\include\xfunctional(125): error C2676: binary '<' : 'const std::string' does not define this operator or a conversion to a type acceptable to the predefined operator ========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========

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  • Problem with std::map and std::pair

    - by Tom
    Hi everyone. I have a small program I want to execute to test something #include <map> #include <iostream> using namespace std; struct _pos{ float xi; float xf; bool operator<(_pos& other){ return this->xi < other.xi; } }; struct _val{ float f; }; int main() { map<_pos,_val> m; struct _pos k1 = {0,10}; struct _pos k2 = {10,15}; struct _val v1 = {5.5}; struct _val v2 = {12.3}; m.insert(std::pair<_pos,_val>(k1,v1)); m.insert(std::pair<_pos,_val>(k2,v2)); return 0; } The problem is that when I try to compile it, I get the following error $ g++ m2.cpp -o mtest In file included from /usr/include/c++/4.4/bits/stl_tree.h:64, from /usr/include/c++/4.4/map:60, from m2.cpp:1: /usr/include/c++/4.4/bits/stl_function.h: In member function ‘bool std::less<_Tp>::operator()(const _Tp&, const _Tp&) const [with _Tp = _pos]’: /usr/include/c++/4.4/bits/stl_tree.h:1170: instantiated from ‘std::pair<typename std::_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::iterator, bool> std::_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::_M_insert_unique(const _Val&) [with _Key = _pos, _Val = std::pair<const _pos, _val>, _KeyOfValue = std::_Select1st<std::pair<const _pos, _val> >, _Compare = std::less<_pos>, _Alloc = std::allocator<std::pair<const _pos, _val> >]’ /usr/include/c++/4.4/bits/stl_map.h:500: instantiated from ‘std::pair<typename std::_Rb_tree<_Key, std::pair<const _Key, _Tp>, std::_Select1st<std::pair<const _Key, _Tp> >, _Compare, typename _Alloc::rebind<std::pair<const _Key, _Tp> >::other>::iterator, bool> std::map<_Key, _Tp, _Compare, _Alloc>::insert(const std::pair<const _Key, _Tp>&) [with _Key = _pos, _Tp = _val, _Compare = std::less<_pos>, _Alloc = std::allocator<std::pair<const _pos, _val> >]’ m2.cpp:30: instantiated from here /usr/include/c++/4.4/bits/stl_function.h:230: error: no match for ‘operator<’ in ‘__x < __y’ m2.cpp:9: note: candidates are: bool _pos::operator<(_pos&) $ I thought that declaring the operator< on the key would solve the problem, but its still there. What could be wrong? Thanks in advance.

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  • Exporting classes containing std:: objects (vector, map, etc) from a dll

    - by RnR
    I'm trying to export classes from a DLL that contain objects such as std::vectors and std::stings - the whole class is declared as dll export through: class DLL_EXPORT FontManager { The problem is that for members of the complex types I get this warning: warning C4251: 'FontManager::m__fonts' : class 'std::map<_Kty,_Ty' needs to have dll-interface to be used by clients of class 'FontManager' with [ _Kty=std::string, _Ty=tFontInfoRef ] I'm able to remove some of the warnings by putting the following forward class declaration before them even though I'm not changing the type of the member variables themselves: template class DLL_EXPORT std::allocator<tCharGlyphProviderRef>; template class DLL_EXPORT std::vector<tCharGlyphProviderRef,std::allocator<tCharGlyphProviderRef> >; std::vector<tCharGlyphProviderRef> m_glyphProviders; Looks like the forward declaration "injects" the DLL_EXPORT for when the member is compiled but is it safe? Does it realy change anything when the client compiles this header and uses the std container on his side? Will it make all future uses of such a container DLL_EXPORT (and possibly not inline?)? And does it really solve the problem that the warning tries to warn about? Is this warning anything I should be worried about or would it be best to disable it in the scope of these constructs? The clients and the dll will always be built using the same set of libraries and compilers and those are header only classes... I'm using Visual Studio 2003 with the standard STD library. ---- Update ---- I'd like to target you more though as I see the answers are general and here we're talking about std containers and types (such as std::string) - maybe the question really is: Can we disable the warning for standard containers and types available to both the client and the dll through the same library headers and treat them just as we'd treat an int or any other built-in type? (It does seem to work correctly on my side.) If so would should be the conditions under which we can do this? Or should maybe using such containers be prohibited or at least ultra care taken to make sure no assignment operators, copy constructors etc will get inlined into the dll client? In general I'd like to know if you feel designing a dll interface having such objects (and for example using them to return stuff to the client as return value types) is a good idea or not and why - I'd like to have a "high level" interface to this functionality... maybe the best solution is what Neil Butterworth suggested - creating a static library?

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  • Multi-threaded Pooled Allocators

    - by Darren Engwirda
    I'm having some issues using pooled memory allocators for std::list objects in a multi-threaded application. The part of the code I'm concerned with runs each thread function in isolation (i.e. there is no communication or synchronization between threads) and therefore I'd like to setup separate memory pools for each thread, where each pool is not thread-safe (and hence fast). I've tried using a shared thread-safe singleton memory pool and found the performance to be poor, as expected. This is a heavily simplified version of the type of thing I'm trying to do. A lot has been included in a pseudo-code kind of way, sorry if it's confusing. /* The thread functor - one instance of MAKE_QUADTREE created for each thread */ class make_quadtree { private: /* A non-thread-safe memory pool for int linked list items, let's say that it's * something along the lines of BOOST::OBJECT_POOL */ pooled_allocator<int> item_pool; /* The problem! - a local class that would be constructed within each std::list as the * allocator but really just delegates to ITEM_POOL */ class local_alloc { public : //!! I understand that I can't access ITEM_POOL from within a nested class like //!! this, that's really my question - can I get something along these lines to //!! work?? pointer allocate (size_t n) { return ( item_pool.allocate(n) ); } }; public : make_quadtree (): item_pool() // only construct 1 instance of ITEM_POOL per // MAKE_QUADTREE object { /* The kind of data structures - vectors of linked lists * The idea is that all of the linked lists should share a local pooled allocator */ std::vector<std::list<int, local_alloc>> lists; /* The actual operations - too complicated to show, but in general: * * - The vector LISTS is grown as a quadtree is built, it's size is the number of * quadtree "boxes" * * - Each element of LISTS (each linked list) represents the ID's of items * contained within each quadtree box (say they're xy points), as the quadtree * is grown a lot of ID pop/push-ing between lists occurs, hence the memory pool * is important for performance */ } }; So really my problem is that I'd like to have one memory pool instance per thread functor instance, but within each thread functor share the pool between multiple std::list objects.

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