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Search found 341 results on 14 pages for 'destructor'.

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  • Another C++ question, delete not working?

    - by kyeana
    New to c++, and am having a problem with delete and destructor (I am sure i am making a stupid mistake here, but haven't been able to figure it out as of yet). When i step through into the destructor, and attepmt to call delete on a pointer, the message shows up "Cannot access memory at address some address." The relevant code is: /* * Removes the front item of the linked list and returns the value stored * in that node. * * TODO - Throws an exception if the list is empty */ std::string LinkedList::RemoveFront() { LinkedListNode *n = pHead->GetNext(); // the node we are removing std::string rtnData = n->GetData(); // the data to return // un-hook the node from the linked list pHead->SetNext(n->GetNext()); n->GetNext()->SetPrev(pHead); // delete the node delete n; n=0; size--; return rtnData; } and /* * Destructor for a linked node. * * Deletes all the dynamically allocated memory, and sets those pointers to 0. */ LinkedListNode::~LinkedListNode() { delete pNext; // This is where the error pops up delete pPrev; pNext=0; pPrev=0; }

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  • Why should we call SuppressFinalize when we dont have a destructor

    - by somaraj
    I have few Question for which I am not able to get a proper answer . 1) Why should we call SuppressFinalize in the Dispose function when we dont have a destructor . 2) Dispose and finalize are used for freeing resources before the object is garbage collected. Whether it is managed or unmanaged resource we need to free it , then why we need a condition inside the dispose funtion , saying pass 'true' when we call this overriden function from IDisposable:Dispose and pass false when called from a finalize. See the below code i copied from net. class Test : IDisposable { private bool isDisposed = false; ~Test() { Dispose(false); } protected void Dispose(bool disposing) { if (disposing) { // Code to dispose the managed resources of the class } // Code to dispose the un-managed resources of the class isDisposed = true; } public void Dispose() { Dispose(true); GC.SuppressFinalize(this); } } what if I remove the boolean protected Dispose function and implement the as below. class Test : IDisposable { private bool isDisposed = false; ~Test() { Dispose(); } public void Dispose() { // Code to dispose the managed resources of the class // Code to dispose the un-managed resources of the class isDisposed = true; // Call this since we have a destructor . what if , if we dont have one GC.SuppressFinalize(this); } }

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  • vector <T *> destructor

    - by Daniel.Z
    I have a class defined like: Class A { public: int num; A *parent; vector<A *> children; ... // constructor without parameters A(void) { this->num = 3; this->parent = 0; for (int i=0;i<num;++i) children.push_back(new A(this,num-1)); } // constructor with parameters A(A *a,int n) { this->num = n; this->children->parent = a; for (int i=0;i<num;++i) this->children.push_back(new A(this,this->num-1)); } }; now, the constructor works fine. there are some problem with destructor. currently, the destructor is defined as: A::~A(void) { if (this->parent!=0) this->parent = 0; for (int i=0;i<(int)children.size();++i) this->children[i]->~A(); vector <A *> ().swap(this->children); } but every time when I debug it, it will break at: void deallocate(pointer _Ptr, size_type) { // deallocate object at _Ptr, ignore size ::operator delete(_Ptr); } it looks like I cannot delete the pointer in the vector of this-children, is there any way that I can de-construct the class successfully?

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  • std::thread and class constructor and destructor

    - by toeplitz
    When testing threads in C++11 I have created the following example: #include <iostream> #include <thread> class Foo { public: Foo(void) { std::cout << "Constructor called: " << this << std::endl; } ~Foo(void) { std::cout << "Destructor called: " << this << std::endl; } void operator()() const { std::cout << "Operatior called: " << this << std::endl; } }; void test_normal(void) { std::cout << "====> Standard example:" << std::endl; Foo f; } void test_thread(void) { std::cout << "====> Thread example:" << std::endl; Foo f; std::thread t(f); t.detach(); } int main(int argc, char **argv) { test_normal(); test_thread(); for(;;); } Which prints the following: Why is the destructor called 6 times for the thread? And why does the thread report different memory locations?

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  • Error using traits class.: "expected constructor destructor or type conversion before '&' token"

    - by Mark
    I have a traits class that's used for printing out different character types: template <typename T> class traits { public: static std::basic_ostream<T>& tout; }; template<> std::ostream& traits<char>::tout = std::cout; template<> std::wostream& traits<unsigned short>::tout = std::wcout; gcc (g++) version 3.4.5 (yes somewhat old) is throwing an error: "expected constructor destructor or type conversion before '&' token" And I'm wondering if there's a good way to resolve this. (it's also angry about _O_WTEXT so if anyone's got some insight into that, I'd also appreciate it)

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  • fcgio.cpp: In destructor 'virtual fcgi_streambuf::~fcgi_streambuf()':

    - by skyeagle
    I am attempting to build fastcgi on a Linux Ubuntu 10.x machine. I run the following commands: ./configure make and I get the following error: fcgio.cpp: In destructor 'virtual fcgi_streambuf::~fcgi_streambuf()': fcgio.cpp:50: error: 'EOF' was not declared in this scope fcgio.cpp: In member function 'virtual int fcgi_streambuf::overflow(int)': fcgio.cpp:70: error: 'EOF' was not declared in this scope fcgio.cpp:75: error: 'EOF' was not declared in this scope fcgio.cpp: In member function 'virtual int fcgi_streambuf::sync()': fcgio.cpp:86: error: 'EOF' was not declared in this scope fcgio.cpp:87: error: 'EOF' was not declared in this scope fcgio.cpp: In member function 'virtual int fcgi_streambuf::underflow()': fcgio.cpp:107: error: 'EOF' was not declared in this scope make[2]: *** [fcgio.lo] Error 1 make[2]: Leaving directory `/somepath/fcgi-2.4.0/libfcgi' make[1]: *** [all-recursive] Error 1 make[1]: Leaving directory `/somepath/fcgi-2.4.0' make: *** [all] Error 2 I notice that others have had the same problem and have asked this question in various fora etc - however, I have not as yet, seen an answer to this question/problem. Has anyone ever managed to build fastcgi on Linux? How do I fix this problem?

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  • Problems with delete in destructor

    - by Vera
    Hello, I wrote this code. The constructor works normally, but in the destructor I get "Windows has triggered a breakpoint." How should I correct this? template class CyclicalArray { private: T* mem_ptr; public: CyclicalArray(size_t capacity, const T& default_value) { this->default_value = default_value; this->capacity = capacity; head_index = 0; mem_ptr = ::new T[capacity]; //memory allocating for(T* p = mem_ptr; p < mem_ptr + capacity * sizeof(T); p += sizeof(T)) { ::new (p) T (default_value); //initialization } } ~CyclicalArray() { for(T* p = mem_ptr + sizeof(T); p < mem_ptr + capacity * sizeof(T); p += sizeof(T)) { p->~T(); } delete[] mem_ptr; }

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  • Is the C++ compiler optimizer allowed to break my destructor ability to be called multiple times?

    - by sharptooth
    We once had an interview with a very experienced C++ developer who couldn't answer the following question: is it necessary to call the base class destructor from the derived class destructor in C++? Obviously the answer is no, C++ will call the base class destructor automagically anyway. But what if we attempt to do the call? As I see it the result will depend on whether the base class destructor can be called twice without invoking erroneous behavior. For example in this case: class BaseSafe { public: ~BaseSafe() { } private: int data; }; class DerivedSafe { public: ~DerivedSafe() { BaseSafe::~BaseSafe(); } }; everything will be fine - the BaseSafe destructor can be called twice safely and the program will run allright. But in this case: class BaseUnsafe { public: BaseUnsafe() { buffer = new char[100]; } ~BaseUnsafe () { delete[] buffer; } private: char* buffer; }; class DerivedUnsafe { public: ~DerivedUnsafe () { BaseUnsafe::~BaseUnsafe(); } }; the explicic call will run fine, but then the implicit (automagic) call to the destructor will trigger double-delete and undefined behavior. Looks like it is easy to avoid the UB in the second case. Just set buffer to null pointer after delete[]. But will this help? I mean the destructor is expected to only be run once on a fully constructed object, so the optimizer could decide that setting buffer to null pointer makes no sense and eliminate that code exposing the program to double-delete. Is the compiler allowed to do that?

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  • cannot use obsolete binding at ‘input’ because it has a destructor

    - by ihm
    here's the word-count I wrote. I got this error: cannot use obsolete binding at ‘input’ because it has a destructor and error: name lookup of ‘input’ changed for ISO ‘for’ scoping what are they suppose to mean? thanks in advance. //rewrite the word-count program using insert instead of subscripting #include <iostream> #include <utility> #include <map> #include <string> using namespace std; int main () { cout<<"please enter some words"<<endl; map<string,int> word_count; for(string input; cin>>input; ) if(!word_count.insert(make_pair(input,1)).second); ++word_count[input]; for(map<string,int>::iterator iter=word_count.begin(); iter!=word_count.end(); ++iter) cout<<iter->first<<": "<<iter->second<<endl; return 0; }

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  • error: expected constructor, destructor, or type conversion before '(' token

    - by jonathanasdf
    include/TestBullet.h:12: error: expected constructor, destructor, or type conver sion before '(' token I hate C++ error messages... lol ^^ Basically, I'm following what was written in this post to try to create a factory class for bullets so they can be instantiated from a string, which will be parsed from an xml file, because I don't want to have a function with a switch for all of the classes because that looks ugly. Here is my TestBullet.h: #pragma once #include "Bullet.h" #include "BulletFactory.h" class TestBullet : public Bullet { public: void init(BulletData& bulletData); void update(); }; REGISTER_BULLET(TestBullet); <-- line 12 And my BulletFactory.h: #pragma once #include <string> #include <map> #include "Bullet.h" #define REGISTER_BULLET(NAME) BulletFactory::reg<NAME>(#NAME) #define REGISTER_BULLET_ALT(NAME, CLASS) BulletFactory::reg<CLASS>(NAME) template<typename T> Bullet * create() { return new T; } struct BulletFactory { typedef std::map<std::string, Bullet*(*)()> bulletMapType; static bulletMapType map; static Bullet * createInstance(char* s) { std::string str(s); bulletMapType::iterator it = map.find(str); if(it == map.end()) return 0; return it->second(); } template<typename T> static void reg(std::string& s) { map.insert(std::make_pair(s, &create<T>)); } }; Thanks in advance.

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  • What's the proper term for a function inverse to a constructor? Deconstructor, destructor, or something else?

    - by Petr Pudlák
    Edit: I'm rephrasing the question a bit. Apparently I caused some confusion because I didn't realize that the term destructor is used in OOP for something quite different - it's a function invoked when an object is being destroyed. In functional programming we (try to) avoid mutable state so there is no such equivalent to it. (I added the proper tag to the question.) Instead, I've seen that the record field for unwrapping a value (especially for single-valued data types such as newtypes) is sometimes called destructor or perhaps deconstructor. For example, let's have (in Haskell): newtype Wrap = Wrap { unwrap :: Int } Here Wrap is the constructor and unwrap is what? I've seen both, for example: ... Most often, one supplies smart constructors and destructors for these to ease working with them. ... at Haskell wiki, or ... The general theme here is to fuse constructor - deconstructor pairs like ... at Haskell wikibook (here it's probably meant in a bit more general sense). The questions are: How do we call unwrap in functional programming? Deconstructor? Destructor? Or by some other term? And to clarify, is this terminology applicable to other functional languages, or is it used just in the Has

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  • right usage of std::uncaught_exception in a destructor

    - by Vokuhila-Oliba
    There are some articles concluding "never throw an exception from a destructor", and "std::uncaught_exception() is not useful", for example: http://www.gotw.ca/gotw/047.htm (written by Herb Sutter) But it seems that I am not getting the point. So I wrote a small testing example (see below). Since everything is fine with the testing example I would very appreciate some comments regarding what might be wrong with it. testing results: ./main Foo::~Foo(): caught exception - but have pending exception - ignoring int main(int, char**): caught exception: from int Foo::bar(int) ./main 1 Foo::~Foo(): caught exception - but *no* exception is pending - rethrowing int main(int, char**): caught exception: from Foo::~Foo() // file main.cpp // build with e.g. "make main" // tested successfully on Ubuntu-Karmic with g++ v4.4.1 #include <iostream> class Foo { public: int bar(int i) { if (0 == i) throw(std::string("from ") + __PRETTY_FUNCTION__); else return i+1; } ~Foo() { bool exc_pending=std::uncaught_exception(); try { bar(0); } catch (const std::string &e) { // ensure that no new exception has been created in the meantime if (std::uncaught_exception()) exc_pending = true; if (exc_pending) { std::cerr << __PRETTY_FUNCTION__ << ": caught exception - but have pending exception - ignoring" << std::endl; } else { std::cerr << __PRETTY_FUNCTION__ << ": caught exception - but *no* exception is pending - rethrowing" << std::endl; throw(std::string("from ") + __PRETTY_FUNCTION__); } } } }; int main(int argc, char** argv) { try { Foo f; // will throw an exception in Foo::bar() if no arguments given. Otherwise // an exception from Foo::~Foo() is thrown. f.bar(argc-1); } catch (const std::string &e) { std::cerr << __PRETTY_FUNCTION__ << ": caught exception: " << e << std::endl; } return 0; }

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  • Destructors in C++

    - by user265260
    does the Destructor deallocate memory assigned to the object which it belongs to or is it just called so that it can perform some last minute housekeeping before the object os deallocated by the compiler?

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  • C++: Life span of temporary arguments?

    - by shoosh
    When creating a new instance of a MyClass as an argument to a function like so: class MyClass { MyClass(int a); }; myFunction(MyClass(42)); does the standard make any grantees on the timing of the destructor? Specifically, can I assume that the it is going to be called before the next statement after the call to myFunction() ?

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  • Alternatives to persisting objects than using __destruct() in PHP

    - by Michael
    I usually use a classes destructor method __destruct() to persist objects to session or what have you. It is just very convinient, but I'm curious to if there are any other methods that are equally appealing. Do you know of such? The curiousity arose as I was to merge/utilize two frameworks that both made use of __destruct() for persistance resulting in a race-problem.

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  • Can someone here explain constructors and destructors in python - simple explanation required - new

    - by rgolwalkar
    i will try to see if it makes sense :- class Person: '''Represnts a person ''' population = 0 def __init__(self,name): //some statements and population += 1 def __del__(self): //some statements and population -= 1 def sayHi(self): '''grettings from person''' print 'Hi My name is %s' % self.name def howMany(self): '''Prints the current population''' if Person.population == 1: print 'i am the only one here' else: print 'There are still %d guyz left ' % Person.population rohan = Person('Rohan') rohan.sayHi() rohan.howMany() sanju = Person('Sanjivi') sanju.howMany() del rohan # am i doing this correctly --- ? i need to get an explanation for this del - destructor O/P:- Initializing person data ****************************************** Initializing Rohan ****************************************** Population now is: 1 Hi My name is Rohan i am the only one here Initializing person data ****************************************** Initializing Sanjivi ****************************************** Population now is: 2 In case Person dies: ****************************************** Sanjivi Bye Bye world there are still 1 people left i am the only one here In case Person dies: ****************************************** Rohan Bye Bye world i am the last person on earth Population now is: 0 If required i can paste the whole lesson as well --- learning from :- http://www.ibiblio.org/swaroopch/byteofpython/read/

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  • Mixed-mode C++/CLI crashing: heap corruption in atexit (static destructor registration)

    - by thaimin
    I am working on deploying a program and the codebase is a mixture of C++/CLI and C#. The C++/CLI comes in all flavors: native, mixed (/clr), and safe (/clr:safe). In my development environment I create a DLL of all the C++/CLI code and reference that from the C# code (EXE). This method works flawlessly. For my releases that I want to release a single executable (simply stating that "why not just have a DLL and EXE separate?" is not acceptable). So far I have succeeded in compiling the EXE with all the different sources. However, when I run it I get the "XXXX has stopped working" dialog with options to Check online, Close and Debug. The problem details are as follows: Problem Event Name: APPCRASH Fault Module Name: StackHash_8d25 Fault Module Version: 6.1.7600.16559 Fault Module Timestamp: 4ba9b29c Exception Code: c0000374 Exception Offset: 000cdc9b OS Version: 6.1.7600.2.0.0.256.48 Locale ID: 1033 Additional Information 1: 8d25 Additional Information 2: 8d25552d834e8c143c43cf1d7f83abb8 Additional Information 3: 7450 Additional Information 4: 74509ce510cd821216ce477edd86119c If I debug and send it to Visual Studio, it reports: Unhandled exception at 0x77d2dc9b in XXX.exe: A heap has been corrupted Choosing break results in it stopping at ntdll.dll!77d2dc9b() with no additional information. If I tell Visual Studio to continue, the program starts up fine and seems to work without incident, probably since a debugger is now attached. What do you make of this? How do I avoid this heap corruption? The program seems to work fine except for this. My abridged compilation script is as follows (I have omitted my error checking for brevity): @set TARGET=x86 @set TARGETX=x86 @set OUT=%TARGETX% @call "%VS90COMNTOOLS%\..\..\VC\vcvarsall.bat" %TARGET% @set WIMGAPI=C:\Program Files\Windows AIK\SDKs\WIMGAPI\%TARGET% set CL=/Zi /nologo /W4 /O2 /GS /EHa /MD /MP /D NDEBUG /D _UNICODE /D UNICODE /D INTEGRATED /Fd%OUT%\ /Fo%OUT%\ set INCLUDE=%WIMGAPI%;%INCLUDE% set LINK=/nologo /LTCG /CLRIMAGETYPE:IJW /MANIFEST:NO /MACHINE:%TARGETX% /SUBSYSTEM:WINDOWS,6.0 /OPT:REF /OPT:ICF /DEFAULTLIB:msvcmrt.lib set LIB=%WIMGAPI%;%LIB% set CSC=/nologo /w:4 /d:INTEGRATED /o+ /target:module :: Compiling resources omitted @set CL_NATIVE=/c /FI"stdafx-native.h" @set CL_MIXED=/c /clr /LN /FI"stdafx-mixed.h" @set CL_PURE=/c /clr:safe /LN /GL /FI"stdafx-pure.h" @set NATIVE=... @set MIXED=... @set PURE=... cl %CL_NATIVE% %NATIVE% cl %CL_MIXED% %MIXED% cl %CL_PURE% %PURE% link /LTCG /NOASSEMBLY /DLL /OUT:%OUT%\core.netmodule %OUT%\*.obj csc %CSC% /addmodule:%OUT%\core.netmodule /out:%OUT%\GUI.netmodule /recurse:*.cs link /FIXED /ENTRY:GUI.Program.Main /OUT:%OUT%\XXX.exe ^ /ASSEMBLYRESOURCE:%OUT%\core.resources,XXX.resources,PRIVATE /ASSEMBLYRESOURCE:%OUT%\GUI.resources,GUI.resources,PRIVATE ^ /ASSEMBLYMODULE:%OUT%\core.netmodule %OUT%\gui.res %OUT%\*.obj %OUT%\GUI.netmodule Update 1 Upon compiling this with debug symbols and trying again, I do in fact get more information. The call stack is: msvcr90d.dll!_msize_dbg(void * pUserData, int nBlockUse) Line 1511 + 0x30 bytes msvcr90d.dll!_dllonexit_nolock(int (void)* func, void (void)* * * pbegin, void (void)* * * pend) Line 295 + 0xd bytes msvcr90d.dll!__dllonexit(int (void)* func, void (void)* * * pbegin, void (void)* * * pend) Line 273 + 0x11 bytes XXX.exe!_onexit(int (void)* func) Line 110 + 0x1b bytes XXX.exe!atexit(void (void)* func) Line 127 + 0x9 bytes XXX.exe!`dynamic initializer for 'Bytes::Null''() Line 7 + 0xa bytes mscorwks.dll!6cbd1b5c() [Frames below may be incorrect and/or missing, no symbols loaded for mscorwks.dll] ... The line of my code that 'causes' this (dynamic initializer for Bytes::Null) is: Bytes Bytes::Null; In the header that is declared as: class Bytes { public: static Bytes Null; } I also tried doing a global extern in the header like so: extern Bytes Null; // header Bytes Null; // cpp file Which failed in the same way. It seems that the CRT atexit function is responsible, being inadvertently required due to the static initializer. Fix As Ben Voigt pointed out the use of any CRT functions (including native static initializers) requires proper initialization of the CRT (which happens in mainCRTStartup, WinMainCRTStartup, or _DllMainCRTStartup). I have added a mixed C++/CLI file that has a C++ main or WinMain: using namespace System; [STAThread] // required if using an STA COM objects (such as drag-n-drop or file dialogs) int main() { // or "int __stdcall WinMain(void*, void*, wchar_t**, int)" for GUI applications array<String^> ^args_orig = Environment::GetCommandLineArgs(); int l = args_orig->Length - 1; // required to remove first argument (program name) array<String^> ^args = gcnew array<String^>(l); if (l > 0) Array::Copy(args_orig, 1, args, 0, l); return XXX::CUI::Program::Main(args); // return XXX::GUI::Program::Main(args); } After doing this, the program now gets a little further, but still has issues (which will be addressed elsewhere): When the program is solely in C# it works fine, along with whenever it is just calling C++/CLI methods, getting C++/CLI properties, and creating managed C++/CLI objects Events added by C# into the C++/CLI code never fire (even though they should) One other weird error is that an exception happens is a InvalidCastException saying can't cast from X to X (where X is the same as X...) However since the heap corruption is fixed (by getting the CRT initialized) the question is done.

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  • Should I call class destructor in this code?

    - by peterg
    I am using this sample to decode/encode some data I am retrieving/sending from/to a web server, and I want to use it like this: BOOL HandleMessage(UINT uMsg,WPARAM wParam,LPARAM lParam,LRESULT* r) { if(uMsg == WM_DESTROY) { PostQuitMessage(0); return TRUE; } else if(uMsg == WM_CREATE) { // Start timer StartTimer(); return TRUE; } else if(uMsg == WM_TIMER) { //get data from server char * test = "test data"; Base64 base64; char *temp = base64.decode(test); MessageBox(TEXT(temp), 0, 0); } } The timer is set every 5 minutes. Should I use delete base64 at the end? Does delete deallocates everything used by base64?

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  • Botan::SecureVector - Destructor called in Constructor???

    - by sheepsimulator
    When using the Botan::SecureVector in the following unit test: void UnitTest() { std::vector<byte> vbData; vbData.push_back(0x04); vbData.push_back(0x04); vbData.push_back(0x04); Botan::SecureVector<Botan::byte> svData(&vbData[0], vbData.size()); CPPUNIT_ASSERT(vbData == std::vector<byte>(svData.begin(), svData.end())); } a segmentation fault occurs when trying to allocate the SecureVector.

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