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  • Are the atomic builtins provided by gcc actually translated into the example code, or is that just f

    - by Jared P
    So I was reading http://gcc.gnu.org/onlinedocs/gcc-4.1.0/gcc/Atomic-Builtins.html, and came across this: type __sync_and_and_fetch (type *ptr, type value, ...) type __sync_xor_and_fetch (type *ptr, type value, ...) type __sync_nand_and_fetch (type *ptr, type value, ...) These builtins perform the operation suggested by the name, and return the new value. That is, { *ptr op= value; return *ptr; } { *ptr = ~*ptr & value; return *ptr; } // nand Is this code literal? or is it just to explain what gcc is doing atomically using c-like syntax? And if this is the direct translation, can someone explain how it is atomic?

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  • Difficulty understanding behavior of free()

    - by Rasmi Ranjan Nayak
    int main() { int *ptr, **ptr1; ptr = (int*)malloc(sizeof(int)); ptr1 = (int**)malloc(sizeof(int)); free(ptr); *ptr = 12345; ptr1 = &ptr; //free(ptr); //**ptr1 = 23456; printf("%d \n", **ptr1); system("pause"); return 0; } How does *ptr store the value 12345, when the memory has already been freed? So, now ptr should be pointing to garbage. Why is this happening?

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  • Estimating the size of a tree

    - by Full Decent
    I'd like to estimate the number of leaves in a large tree structure for which I can't visit every node exhaustively. Is this algorithm appropriate? Does it have a name? Also, please pedant if I am using any terms improperly. sum_trials = 0 num_trials = 0 WHILE time_is_not_up bits = 0 ptr = tree.root WHILE count(ptr.children) > 0 bits += log2(count(ptr.children)) ptr = ptr.children[rand()%count(ptr.children)] sum_trials += bits num_trials++ estimated_tree_size = 2^(sum_trials/num_trials)

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  • Internal typedef and circular dependency

    - by bcr
    I have two classes whose functions take typedefed pointers to eachother as return values and parameters. I.e.: class Segment; class Location : public Fwk::NamedInterface { public: // ===== Class Typedefs ===== typedef Fwk::Ptr<Location const> PtrConst; typedef Fwk::Ptr<Location> Ptr; // ===== Class Typedefs End ===== void segmentIs(Segment::Ptr seg); /* ... */ } and class Location; class Segment : public Fwk::NamedInterface { public: // ===== Class Typedefs ===== typedef Fwk::Ptr<Segment const> PtrConst; typedef Fwk::Ptr<Segment> Ptr; // ===== Class Typedefs End ===== void locationIs(Location::Ptr seg); /* ... */ } This understandably generated linker errors...which the forward declarations of the respective classes don't fix. How can I forward declare the Ptr and PtrConst typedefs while keeping these typedefs internal to the class (i.e. I would like to write Location::Ptr to refer to the location pointer type)? Thanks folks!

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  • Searching strings C

    - by Skittles
    First time posting here so I'm sorry if I mess up. I need to search a string and return any strings containing the search data with the search data highlighted. If my string is Hi my name is and I searched name it would produce Hi my NAME is This is a quick code I wrote that works but it only works once. If I try and search again it seg faults. I was hoping someone could hint me at a better way to write this because this code is disgusting! void search(char * srcStr, int n){ int cnt = 0, pnt,i = 0; char tmpText[500]; char tmpName[500]; char *ptr, *ptr2, *ptrLast; int num; while(*(node->text+cnt) != '\0'){ //finds length of string cnt++; } for(pnt = 0; pnt < cnt; pnt++){ //copies node->text into a tmp string tmpText[pnt] = *(node->text+pnt); } tmpText[pnt+1] = '\0'; //prints up to first occurrence of srcStr ptr = strcasestr(tmpText, srcStr); for(num = 0; num < ptr-tmpText; num++){ printf("%c",tmpText[num]); } //prints first occurrence of srcStr in capitals for(num = 0; num < n; num++){ printf("%c",toupper(tmpText[ptr-tmpText+num])); } ptr2 = strcasestr((ptr+n),srcStr); for(num = (ptr-tmpText+n); num < (ptr2-tmpText); num++){ printf("%c",tmpText[num]); } while((ptr = strcasestr((ptr+n), srcStr)) != NULL){ ptr2 = strcasestr((ptr+n),srcStr); for(num = (ptr-tmpText+n); num < (ptr2-tmpText); num++){ printf("%c",tmpText[num]); } for(num = 0; num < n; num++){ printf("%c",toupper(tmpText[ptr-tmpText+num])); } ptrLast = ptr; } //prints remaining string after last occurrence for(num = (ptrLast-tmpText+n); num < cnt; num++){ printf("%c",tmpText[num]); } }

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  • Mixing C and C++, raw pointers and (boost) shared pointers

    - by oompahloompah
    I am working in C++ with some legacy C code. I have a data structure that (during initialisation), makes a copy of the structure pointed to a ptr passed to its initialisation pointer. Here is a simplification of what I am trying to do - hopefully, no important detail has been lost in the "simplification": /* C code */ typedef struct MyData { double * elems; unsigned int len; }; int NEW_mydata(MyData* data, unsigned int len) { // no error checking data->elems = (double *)calloc(len, sizeof(double)); return 0; } typedef struct Foo { MyData data data_; }; void InitFoo(Foo * foo, const MyData * the_data) { //alloc mem etc ... then assign the STRUCTURE foo.data_ = *thedata ; } C++ code ------------- typedef boost::shared_ptr<MyData> MyDataPtr; typedef std::map<std::string, MyDataPtr> Datamap; class FooWrapper { public: FooWrapper(const std::string& key) { MyDataPtr mdp = dmap[key]; InitFoo(&m_foo, const_cast<MyData*>((*mdp.get()))); } ~FooWrapper(); double get_element(unsigned int index ) const { return m_foo.elems[index]; } private: // non copyable, non-assignable FooWrapper(const FooWrapper&); FooWrapper& operator= (const FooWrapper&); Foo m_foo; }; int main(int argc, char *argv[]) { MyData data1, data2; Datamap dmap; NEW_mydata(&data1, 10); data1->elems[0] = static_cast<double>(22/7); NEW_mydata(&data2, 42); data2->elems[0] = static_cast<double>(13/21); boost::shared_ptr d1(&data1), d2(&data2); dmap["data1"] = d1; dmap["data2"] = d2; FooWrapper fw("data1"); //expect 22/7, get something else (random number?) double ret fw.get_element(0); } Essentially, what I want to know is this: Is there any reason why the data retrieved from the map is different from the one stored in the map?

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  • C Programming: malloc() for a 2D array (using pointer-to-pointer)

    - by vikramtheone
    Hi Guys, yesterday I had posted a question: How should I pass a pointer to a function and allocate memory for the passed pointer from inside the called function? From the answers I got, I was able to understand what mistake I was doing. I'm facing a new problem now, can anyone help out with this? I want to dynamically allocate a 2D array, so I'm passing a Pointer-to-Pointer from my main() to another function called alloc_2D_pixels(...), where I use malloc(...) and for(...) loop to allocate memory for the 2D array. Well, after returning from the alloc_2D_pixels(...) function, the pointer-to-pointer still remains NULL, so naturally, when I try accessing or try to free(...) the Pointer-to-Pointer, the program hangs. Can anyone suggest me what mistakes I'm doing here? Help!!! Vikram SOURCE: main() { unsigned char **ptr; unsigned int rows, cols; if(alloc_2D_pixels(&ptr, rows, cols)==ERROR) // Satisfies this condition printf("Memory for the 2D array not allocated"); // NO ERROR is returned if(ptr == NULL) // ptr is NULL so no memory was allocated printf("Yes its NULL!"); // Because ptr is NULL, with any of these 3 statements below the program HANGS ptr[0][0] = 10; printf("Element: %d",ptr[0][0]); free_2D_alloc(&ptr); } signed char alloc_2D_pixels(unsigned char ***memory, unsigned int rows, unsigned int cols) { signed char status = NO_ERROR; memory = malloc(rows * sizeof(unsigned char** )); if(memory == NULL) { status = ERROR; printf("ERROR: Memory allocation failed!"); } else { int i; for(i = 0; i< cols; i++) { memory[i] = malloc(cols * sizeof(unsigned char)); if(memory[i]==NULL) { status = ERROR; printf("ERROR: Memory allocation failed!"); } } } // Inserted the statements below for debug purpose only memory[0][0] = (unsigned char)10; // I'm able to access the array from printf("\nElement %d",memory[0][0]); // here with no problems return status; } void free_2D_pixels(unsigned char ***ptr, unsigned int rows) { int i; for(i = 0; i < rows; i++) { free(ptr[i]); } free(ptr); }

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  • C++ vector of strings, pointers to functions, and the resulting frustration.

    - by Kyle
    So I am a first year computer science student, for on of my final projects, I need to write a program that takes a vector of strings, and applies various functions to these. Unfortunately, I am really confused on how to use pointer to pass the vector from function to function. Below is some sample code to give an idea of what I am talking about. I also get an error message when I try to deference any pointer. thanks. #include <iostream> #include <cstdlib> #include <vector> #include <string> using namespace std; vector<string>::pointer function_1(vector<string>::pointer ptr); void function_2(vector<string>::pointer ptr); int main() { vector<string>::pointer ptr; vector<string> svector; ptr = &svector[0]; function_1(ptr); function_2(ptr); } vector<string>::pointer function_1(vector<string>::pointer ptr) { string line; for(int i = 0; i < 10; i++) { cout << "enter some input ! \n"; // i need to be able to pass a reference of the vector getline(cin, line); // through various functions, and have the results *ptr.pushback(line); // reflectedin main(). But I cannot use member functions } // of vector with a deferenced pointer. return(ptr); } void function_2(vector<string>::pointer ptr) { for(int i = 0; i < 10; i++) { cout << *ptr[i] << endl; } }

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  • safe dereferencing and deletion

    - by serejko
    Hi, I'm relatively new to C++ and OOP in general and currently trying to make such a class that allows to dereference and delete a dead or invalid pointer without any care of having undefined behavior or program fault in result, and I want to ask you is it a good idea and is there something similar which is already implemented by someone else? or maybe I'm doing something completely wrong? I've just started making it and here is the code I currently have: template<class T> class SafeDeref { public: T& operator *() { hash_set<T*>::iterator it = theStore.find(reinterpret_cast<T*>(ptr)); if (it != theStore.end()) return *this; return theDefaultObject; } T* operator ->() { hash_set<T*>::iterator it = theStore.find(reinterpret_cast<T*>(ptr)); if (it != theStore.end()) return this; return &theDefaultObject; } void* operator new(size_t size) { void* ptr = malloc(size * sizeof(T)); if (ptr != 0) theStore.insert(reinterpret_cast<T*>(ptr)); return ptr; } void operator delete(void* ptr) { hash_set<T*>::iterator it = theStore.find(reinterpret_cast<T*>(ptr)); if (it != theStore.end()) { theStore.erase(it); free(ptr); } } protected: static bool isInStore(T* ptr) { return theStore.find(ptr) != theStore.end(); } private: static T theDefaultObject; static hash_set<T*> theStore; }; The idea is that each class with the safe dereference should be inherited from it like this: class Foo : public SafeDeref<Foo> { void doSomething(); }; So... Any advices? Thanks in advance. P.S. If you're wondering why I need this... well, I'm creating a set of native functions for some scripting environment, and all of them use pointers to internally allocated objects as handles to them and they're able to delete them as well (input data can be wrong), so this is kinda protection from damaging host application's memory And I really sorry for my bad English

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  • What are the right reverse PTR, domain keys, and SPF settings for two domains running the same appli

    - by James A. Rosen
    I just read Jeff Atwood's recent post on DNS configuration for email and decided to give it a go on my application. I have a web-app that runs on one server under two different IPs and domain names, on both HTTP and HTTPS for each: <VirtualHost *:80> ServerName foo.org ServerAlias www.foo.org ... </VirtualHost> <VirtualHost 1.2.3.4:443> ServerName foo.org ServerAlias www.foo.org </VirtualHost> <VirtualHost *:80> ServerName bar.org ServerAlias www.bar.org ... </VirtualHost> <VirtualHost 2.3.4.5:443> ServerName bar.org ServerAlias www.bar.org </VirtualHost> I'm using GMail as my SMTP server. Do I need the reverse PTR and SenderID records? If so, do I put the same ones on all of my records (foo.org, www.foo.org, bar.org, www.bar.org, ASPMX.L.GOOGLE.COM, ASPMX2.GOOGLEMAIL.COM, ..)? I'm pretty sure I want the domain-keys records, but I'm not sure which domains to attach them to. The Google mail servers? foo.org and bar.org? Everything?

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  • §non_lazy_ptr iphone sdk 3.0

    - by Hans Espen
    After I built my iphone 2.2.1 application in sdk 3.0, I get a lot of errors of type §non_lazy_ptr. I am getting it on the CFFTPStream constants, like kCFStreamPropertyFTPPassword and kCFStreamPropertyUserName. Anyone know what causes this?

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  • Using mem_fun_ref with boost::shared_ptr

    - by BlueRaja
    Following the advice of this page, I'm trying to get shared_ptr to call IUnknown::Release() instead of delete: IDirectDrawSurface* dds; ... //Allocate dds return shared_ptr<IDirectDrawSurface>(dds, mem_fun_ref(&IUnknown::Release)); error C2784: 'std::const_mem_fun1_ref_t<_Result,_Ty,_Arg std::mem_fun_ref(Result (_thiscall _Ty::* )(_Arg) const)' : could not deduce template argument for 'Result (_thiscall _Ty::* )(Arg) const' from 'ULONG (_cdecl IUnknown::* )(void)' error C2784: 'std::const_mem_fun_ref_t<_Result,_Ty std::mem_fun_ref(Result (_thiscall _Ty::* )(void) const)' : could not deduce template argument for 'Result (_thiscall _Ty::* )(void) const' from 'ULONG (__cdecl IUnknown::* )(void)' error C2784: 'std::mem_fun1_ref_t<_Result,_Ty,_Arg std::mem_fun_ref(Result (_thiscall _Ty::* )(_Arg))' : could not deduce template argument for 'Result (_thiscall _Ty::* )(Arg)' from 'ULONG (_cdecl IUnknown::* )(void)' error C2784: 'std::mem_fun_ref_t<_Result,_Ty std::mem_fun_ref(Result (_thiscall _Ty::* )(void))' : could not deduce template argument for 'Result (_thiscall _Ty::* )(void)' from 'ULONG (__cdecl IUnknown::* )(void)' error C2661: 'boost::shared_ptr::shared_ptr' : no overloaded function takes 2 arguments I have no idea what to make of this. My limited template/functor knowledge led me to try typedef ULONG (IUnknown::*releaseSignature)(void); shared_ptr<IDirectDrawSurface>(dds, mem_fun_ref(static_cast<releaseSignature>(&IUnknown::Release))); But to no avail. Any ideas?

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  • Intellisense fails for boost::shared_ptr with Boost 1.40.0 in Visual Studio 2008

    - by Edward Loper
    I'm having trouble getting intellisense to auto-complete shared pointers for boost 1.40.0. (It works fine for Boost 1.33.1.) Here's a simple sample project file where auto-complete does not work: #include <boost/shared_ptr.hpp> struct foo { bool func() { return true; }; }; void bar() { boost::shared_ptr<foo> pfoo; pfoo.get(); // <-- intellisense does not autocomplete after "pfoo." pfoo->func(); // <-- intellisense does not autocomplete after "pfoo->" } When I right-click on shared_ptr, and do "Go to Definition," it brings be to a forward-declaration of the shared_ptr class in . It does not bring me to the actual definition, which is in However, it compiles fine, and auto-completion works fine for "boost::." Also, auto-completion works fine for boost::scoped_ptr and for boost::shared_array. Any ideas?

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  • Can I use boost::make_shared with a private constructor?

    - by Billy ONeal
    Consider the following: class DirectoryIterator; namespace detail { class FileDataProxy; class DirectoryIteratorImpl { friend class DirectoryIterator; friend class FileDataProxy; WIN32_FIND_DATAW currentData; HANDLE hFind; std::wstring root; DirectoryIteratorImpl(); explicit DirectoryIteratorImpl(const std::wstring& pathSpec); void increment(); public: ~DirectoryIteratorImpl() {}; }; class FileDataProxy //Serves as a proxy to the WIN32_FIND_DATA struture inside the iterator. { friend class DirectoryIterator; boost::shared_ptr<DirectoryIteratorImpl> iteratorSource; FileDataProxy(boost::shared_ptr<DirectoryIteratorImpl> parent) : iteratorSource(parent) {}; public: std::wstring GetFolderPath() const { return iteratorSource->root; } }; } class DirectoryIterator : public boost::iterator_facade<DirectoryIterator, detail::FileDataProxy, std::input_iterator_tag> { friend class boost::iterator_core_access; boost::shared_ptr<detail::DirectoryIteratorImpl> impl; void increment() { impl->increment(); }; detail::FileDataProxy dereference() const { return detail::FileDataProxy(impl); }; public: DirectoryIterator() { impl = boost::make_shared<detail::DirectoryIteratorImpl>(); }; }; It seems like DirectoryIterator should be able to call boost::make_shared<DirectoryIteratorImpl>, because it is a friend of DirectoryIteratorImpl. However, this code fails to compile because the constructor for DirectoryIteratorImpl is private. Since this class is an internal implementation detail that clients of DirectoryIterator should never touch, it would be nice if I could keep the constructor private. Is this my fundamental misunderstanding around make_shared or do I need to mark some sort of boost piece as friend in order for the call to compile?

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  • Trouble move-capturing std::unique_ptr in a lambda using std::bind

    - by user2478832
    I'd like to capture a variable of type std::vector<std::unique_ptr<MyClass>> in a lambda expression (in other words, "capture by move"). I found a solution which uses std::bind to capture unique_ptr (http://stackoverflow.com/a/12744730/2478832) and decided to use it as a starting point. However, the most simplified version of the proposed code I could get doesn't compile (lots of template mistakes, it seems to try to call unique_ptr's copy constructor). #include <functional> #include <memory> std::function<void ()> a(std::unique_ptr<int>&& param) { return std::bind( [] (int* p) {}, std::move(param)); } int main() { a(std::unique_ptr<int>(new int())); } Can anybody point out what is wrong with this code? EDIT: tried changing the lambda to take a reference to unique_ptr, it still doesn't compile. #include <functional> #include <memory> std::function<void ()> a(std::unique_ptr<int>&& param) { return std::bind( [] (std::unique_ptr<int>& p) {}, // also as a const reference std::move(param)); } int main() { a(std::unique_ptr<int>(new int())); }

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  • The cost of passing by shared_ptr

    - by Artem
    I use std::tr1::shared_ptr extensively throughout my application. This includes passing objects in as function arguments. Consider the following: class Dataset {...} void f( shared_ptr< Dataset const > pds ) {...} void g( shared_ptr< Dataset const > pds ) {...} ... While passing a dataset object around via shared_ptr guarantees its existence inside f and g, the functions may be called millions of times, which causes a lot of shared_ptr objects being created and destroyed. Here's a snippet of the flat gprof profile from a recent run: Each sample counts as 0.01 seconds. % cumulative self self total time seconds seconds calls s/call s/call name 9.74 295.39 35.12 2451177304 0.00 0.00 std::tr1::__shared_count::__shared_count(std::tr1::__shared_count const&) 8.03 324.34 28.95 2451252116 0.00 0.00 std::tr1::__shared_count::~__shared_count() So, ~17% of the runtime was spent on reference counting with shared_ptr objects. Is this normal? A large portion of my application is single-threaded and I was thinking about re-writing some of the functions as void f( const Dataset& ds ) {...} and replacing the calls shared_ptr< Dataset > pds( new Dataset(...) ); f( pds ); with f( *pds ); in places where I know for sure the object will not get destroyed while the flow of the program is inside f(). But before I run off to change a bunch of function signatures / calls, I wanted to know what the typical performance hit of passing by shared_ptr was. Seems like shared_ptr should not be used for functions that get called very often. Any input would be appreciated. Thanks for reading. -Artem

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  • Why isn't the reference counter in boost::shared_ptr volatile?

    - by Johann Gerell
    In the boost::shared_ptr destructor, this is done: if(--*pn == 0) { boost::checked_delete(px); delete pn; } where pn is a pointer to the reference counter, which is typedefed as shared_ptr::count_type -> detail::atomic_count -> long I would have expected the long to be volatile long, given threaded usage and the non-atomic 0-check-and-deletion in the shared_ptr destructor above. Why isn't it volatile?

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  • Memory leak using shared_ptr

    - by nabulke
    Both code examples compile and run without problems. Using the second variant results in a memory leak. Any ideas why? Thanks in advance for any help. Variant 1: typedef boost::shared_ptr<ParameterTabelle> SpParameterTabelle; struct ParTabSpalteData { ParTabSpalteData(const SpParameterTabelle& tabelle, const string& id) :Tabelle(tabelle), Id(id) { } const SpParameterTabelle& Tabelle; string Id; }; Variant 2: struct ParTabSpalteData { ParTabSpalteData(const SpParameterTabelle& tabelle, const string& id) :Id(id) { // causes memory leak Tabelle2 = tabelle; } SpParameterTabelle Tabelle2; string Id; };

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  • Compilation problems with vector<auto_ptr<> >

    - by petersohn
    Consider the following code: #include <iostream> #include <memory> #include <vector> using namespace std; struct A { int a; A(int a_):a(a_) {} }; int main() { vector<auto_ptr<A> > as; for (int i = 0; i < 10; i++) { auto_ptr<A> a(new A(i)); as.push_back(a); } for (vector<auto_ptr<A> >::iterator it = as.begin(); it != as.end(); ++it) cout << (*it)->a << endl; } When trying to compile it, I get the following obscure compiler error from g++: g++ -O0 -g3 -Wall -c -fmessage-length=0 -MMD -MP -MF"src/proba.d" -MT"src/proba.d" -o"src/proba.o" "../src/proba.cpp" /usr/include/c++/4.1.2/ext/new_allocator.h: In member function ‘void __gnu_cxx::new_allocator<_Tp>::construct(_Tp*, const _Tp&) [with _Tp = std::auto_ptr<A>]’: /usr/include/c++/4.1.2/bits/stl_vector.h:606: instantiated from ‘void std::vector<_Tp, _Alloc>::push_back(const _Tp&) [with _Tp = std::auto_ptr<A>, _Alloc = std::allocator<std::auto_ptr<A> >]’ ../src/proba.cpp:19: instantiated from here /usr/include/c++/4.1.2/ext/new_allocator.h:104: error: passing ‘const std::auto_ptr<A>’ as ‘this’ argument of ‘std::auto_ptr<_Tp>::operator std::auto_ptr_ref<_Tp1>() [with _Tp1 = A, _Tp = A]’ discards qualifiers /usr/include/c++/4.1.2/bits/vector.tcc: In member function ‘void std::vector<_Tp, _Alloc>::_M_insert_aux(__gnu_cxx::__normal_iterator<typename std::_Vector_base<_Tp, _Alloc>::_Tp_alloc_type::pointer, std::vector<_Tp, _Alloc> >, const _Tp&) [with _Tp = std::auto_ptr<A>, _Alloc = std::allocator<std::auto_ptr<A> >]’: /usr/include/c++/4.1.2/bits/stl_vector.h:610: instantiated from ‘void std::vector<_Tp, _Alloc>::push_back(const _Tp&) [with _Tp = std::auto_ptr<A>, _Alloc = std::allocator<std::auto_ptr<A> >]’ ../src/proba.cpp:19: instantiated from here /usr/include/c++/4.1.2/bits/vector.tcc:256: error: passing ‘const std::auto_ptr<A>’ as ‘this’ argument of ‘std::auto_ptr<_Tp>::operator std::auto_ptr_ref<_Tp1>() [with _Tp1 = A, _Tp = A]’ discards qualifiers /usr/include/c++/4.1.2/bits/stl_construct.h: In function ‘void std::_Construct(_T1*, const _T2&) [with _T1 = std::auto_ptr<A>, _T2 = std::auto_ptr<A>]’: /usr/include/c++/4.1.2/bits/stl_uninitialized.h:86: instantiated from ‘_ForwardIterator std::__uninitialized_copy_aux(_InputIterator, _InputIterator, _ForwardIterator, __false_type) [with _InputIterator = __gnu_cxx::__normal_iterator<std::auto_ptr<A>*, std::vector<std::auto_ptr<A>, std::allocator<std::auto_ptr<A> > > >, _ForwardIterator = __gnu_cxx::__normal_iterator<std::auto_ptr<A>*, std::vector<std::auto_ptr<A>, std::allocator<std::auto_ptr<A> > > >]’ /usr/include/c++/4.1.2/bits/stl_uninitialized.h:113: instantiated from ‘_ForwardIterator std::uninitialized_copy(_InputIterator, _InputIterator, _ForwardIterator) [with _InputIterator = __gnu_cxx::__normal_iterator<std::auto_ptr<A>*, std::vector<std::auto_ptr<A>, std::allocator<std::auto_ptr<A> > > >, _ForwardIterator = __gnu_cxx::__normal_iterator<std::auto_ptr<A>*, std::vector<std::auto_ptr<A>, std::allocator<std::auto_ptr<A> > > >]’ /usr/include/c++/4.1.2/bits/stl_uninitialized.h:254: instantiated from ‘_ForwardIterator std::__uninitialized_copy_a(_InputIterator, _InputIterator, _ForwardIterator, std::allocator<_Tp>) [with _InputIterator = __gnu_cxx::__normal_iterator<std::auto_ptr<A>*, std::vector<std::auto_ptr<A>, std::allocator<std::auto_ptr<A> > > >, _ForwardIterator = __gnu_cxx::__normal_iterator<std::auto_ptr<A>*, std::vector<std::auto_ptr<A>, std::allocator<std::auto_ptr<A> > > >, _Tp = std::auto_ptr<A>]’ /usr/include/c++/4.1.2/bits/vector.tcc:279: instantiated from ‘void std::vector<_Tp, _Alloc>::_M_insert_aux(__gnu_cxx::__normal_iterator<typename std::_Vector_base<_Tp, _Alloc>::_Tp_alloc_type::pointer, std::vector<_Tp, _Alloc> >, const _Tp&) [with _Tp = std::auto_ptr<A>, _Alloc = std::allocator<std::auto_ptr<A> >]’ /usr/include/c++/4.1.2/bits/stl_vector.h:610: instantiated from ‘void std::vector<_Tp, _Alloc>::push_back(const _Tp&) [with _Tp = std::auto_ptr<A>, _Alloc = std::allocator<std::auto_ptr<A> >]’ ../src/proba.cpp:19: instantiated from here /usr/include/c++/4.1.2/bits/stl_construct.h:81: error: passing ‘const std::auto_ptr<A>’ as ‘this’ argument of ‘std::auto_ptr<_Tp>::operator std::auto_ptr_ref<_Tp1>() [with _Tp1 = A, _Tp = A]’ discards qualifiers make: *** [src/proba.o] Error 1 It seems to me that there is some kind of problem with consts here. Does this mean that auto_ptr can't be used in vectors?

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  • pushing back an boost::ptr_vector<...>::iterator in another boost::ptr_vector?

    - by Ethan Nash
    Hi all, I have the following code (just typed it in here, might have typos or stuff): typedef boost::ptr_vector<SomeClass> tvec; tvec v; // ... fill v ... tvec vsnap; for(tvec::iterator it = v.begin(); it != v.end(); ++it) { if((*v).anyCondition) vsnap.push_back( it ); // (*it) or &(*it) doesn't work } My problem is now that i cant push_back an iterator in any way, I just don't get the pointer out of the iterator. Is there an easy way i didnt see, or are boosts ptr_vector the false choice for this case? Thanks in advance.

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  • Compilng problems with vector<auto_ptr<> >

    - by petersohn
    Consider the following code: #include <iostream> #include <memory> #include <vector> using namespace std; struct A { int a; A(int a_):a(a_) {} }; int main() { vector<auto_ptr<A> > as; for (int i = 0; i < 10; i++) { auto_ptr<A> a(new A(i)); as.push_back(a); } for (vector<auto_ptr<A> >::iterator it = as.begin(); it != as.end(); ++it) cout << (*it)->a << endl; } When trying to compile it, I get the following obscure compiler error from g++: g++ -O0 -g3 -Wall -c -fmessage-length=0 -MMD -MP -MF"src/proba.d" -MT"src/proba.d" -o"src/proba.o" "../src/proba.cpp" /usr/include/c++/4.1.2/ext/new_allocator.h: In member function ‘void __gnu_cxx::new_allocator<_Tp>::construct(_Tp*, const _Tp&) [with _Tp = std::auto_ptr<A>]’: /usr/include/c++/4.1.2/bits/stl_vector.h:606: instantiated from ‘void std::vector<_Tp, _Alloc>::push_back(const _Tp&) [with _Tp = std::auto_ptr<A>, _Alloc = std::allocator<std::auto_ptr<A> >]’ ../src/proba.cpp:19: instantiated from here /usr/include/c++/4.1.2/ext/new_allocator.h:104: error: passing ‘const std::auto_ptr<A>’ as ‘this’ argument of ‘std::auto_ptr<_Tp>::operator std::auto_ptr_ref<_Tp1>() [with _Tp1 = A, _Tp = A]’ discards qualifiers /usr/include/c++/4.1.2/bits/vector.tcc: In member function ‘void std::vector<_Tp, _Alloc>::_M_insert_aux(__gnu_cxx::__normal_iterator<typename std::_Vector_base<_Tp, _Alloc>::_Tp_alloc_type::pointer, std::vector<_Tp, _Alloc> >, const _Tp&) [with _Tp = std::auto_ptr<A>, _Alloc = std::allocator<std::auto_ptr<A> >]’: /usr/include/c++/4.1.2/bits/stl_vector.h:610: instantiated from ‘void std::vector<_Tp, _Alloc>::push_back(const _Tp&) [with _Tp = std::auto_ptr<A>, _Alloc = std::allocator<std::auto_ptr<A> >]’ ../src/proba.cpp:19: instantiated from here /usr/include/c++/4.1.2/bits/vector.tcc:256: error: passing ‘const std::auto_ptr<A>’ as ‘this’ argument of ‘std::auto_ptr<_Tp>::operator std::auto_ptr_ref<_Tp1>() [with _Tp1 = A, _Tp = A]’ discards qualifiers /usr/include/c++/4.1.2/bits/stl_construct.h: In function ‘void std::_Construct(_T1*, const _T2&) [with _T1 = std::auto_ptr<A>, _T2 = std::auto_ptr<A>]’: /usr/include/c++/4.1.2/bits/stl_uninitialized.h:86: instantiated from ‘_ForwardIterator std::__uninitialized_copy_aux(_InputIterator, _InputIterator, _ForwardIterator, __false_type) [with _InputIterator = __gnu_cxx::__normal_iterator<std::auto_ptr<A>*, std::vector<std::auto_ptr<A>, std::allocator<std::auto_ptr<A> > > >, _ForwardIterator = __gnu_cxx::__normal_iterator<std::auto_ptr<A>*, std::vector<std::auto_ptr<A>, std::allocator<std::auto_ptr<A> > > >]’ /usr/include/c++/4.1.2/bits/stl_uninitialized.h:113: instantiated from ‘_ForwardIterator std::uninitialized_copy(_InputIterator, _InputIterator, _ForwardIterator) [with _InputIterator = __gnu_cxx::__normal_iterator<std::auto_ptr<A>*, std::vector<std::auto_ptr<A>, std::allocator<std::auto_ptr<A> > > >, _ForwardIterator = __gnu_cxx::__normal_iterator<std::auto_ptr<A>*, std::vector<std::auto_ptr<A>, std::allocator<std::auto_ptr<A> > > >]’ /usr/include/c++/4.1.2/bits/stl_uninitialized.h:254: instantiated from ‘_ForwardIterator std::__uninitialized_copy_a(_InputIterator, _InputIterator, _ForwardIterator, std::allocator<_Tp>) [with _InputIterator = __gnu_cxx::__normal_iterator<std::auto_ptr<A>*, std::vector<std::auto_ptr<A>, std::allocator<std::auto_ptr<A> > > >, _ForwardIterator = __gnu_cxx::__normal_iterator<std::auto_ptr<A>*, std::vector<std::auto_ptr<A>, std::allocator<std::auto_ptr<A> > > >, _Tp = std::auto_ptr<A>]’ /usr/include/c++/4.1.2/bits/vector.tcc:279: instantiated from ‘void std::vector<_Tp, _Alloc>::_M_insert_aux(__gnu_cxx::__normal_iterator<typename std::_Vector_base<_Tp, _Alloc>::_Tp_alloc_type::pointer, std::vector<_Tp, _Alloc> >, const _Tp&) [with _Tp = std::auto_ptr<A>, _Alloc = std::allocator<std::auto_ptr<A> >]’ /usr/include/c++/4.1.2/bits/stl_vector.h:610: instantiated from ‘void std::vector<_Tp, _Alloc>::push_back(const _Tp&) [with _Tp = std::auto_ptr<A>, _Alloc = std::allocator<std::auto_ptr<A> >]’ ../src/proba.cpp:19: instantiated from here /usr/include/c++/4.1.2/bits/stl_construct.h:81: error: passing ‘const std::auto_ptr<A>’ as ‘this’ argument of ‘std::auto_ptr<_Tp>::operator std::auto_ptr_ref<_Tp1>() [with _Tp1 = A, _Tp = A]’ discards qualifiers make: *** [src/proba.o] Error 1 It seems to me that there is some kind of problem with consts here. Does this mean that auto_ptr can't be used in vectors?

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  • How can I get this code involving unique_ptr to compile?!

    - by Neil G
    #include <vector> #include <memory> using namespace std; class A { public: A(): i(new int) {} A(A const& a) = delete; A(A &&a): i(move(a.i)) {} unique_ptr<int> i; }; class AGroup { public: void AddA(A &&a) { a_.emplace_back(move(a)); } vector<A> a_; }; int main() { AGroup ag; ag.AddA(A()); return 0; } does not compile... (says that unique_ptr's copy constructor is deleted) I tried replacing move with forward. Not sure if I did it right, but it didn't work for me.

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  • should std::auto_ptr<>::operator = reset / deallocate its existing pointee ?

    - by afriza
    I read here about std::auto_ptr<::operator= Notice however that the left-hand side object is not automatically deallocated when it already points to some object. You can explicitly do this by calling member function reset before assigning it a new value. However, when I read the source code for header file C:\Program Files\Microsoft Visual Studio 8\VC\ce\include\memory template<class _Other> auto_ptr<_Ty>& operator=(auto_ptr<_Other>& _Right) _THROW0() { // assign compatible _Right (assume pointer) reset(_Right.release()); return (*this); } auto_ptr<_Ty>& operator=(auto_ptr<_Ty>& _Right) _THROW0() { // assign compatible _Right (assume pointer) reset(_Right.release()); return (*this); } auto_ptr<_Ty>& operator=(auto_ptr_ref<_Ty> _Right) _THROW0() { // assign compatible _Right._Ref (assume pointer) _Ty **_Pptr = (_Ty **)_Right._Ref; _Ty *_Ptr = *_Pptr; *_Pptr = 0; // release old reset(_Ptr); // set new return (*this); } What is the correct/standard behavior? How do other STL implementations behave?

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