Re: Problems with using auto_ptr and _CRTDBG_MAP_ALLOC

From:

"Tom Widmer [VC++ MVP]" <tom_usenet@hotmail.com>

Newsgroups:

microsoft.public.vc.language

Date:

Tue, 11 Jul 2006 10:52:09 +0100

Message-ID:

<ufjUu#MpGHA.1592@TK2MSFTNGP04.phx.gbl>

peter.linlin@gmail.com wrote:

Hi All,

What I intend to do and ask for your help is how to use the facility
provided by VC itself to detect and prevent memory leaking.

I have been trying to use auto_ptr and __CRTDBG_MAP_ALLOC to prevent
memory leaks in my application development by doing the following:

1. Include the following in the stdafx.h
#ifdef _DEBUG
    // When debugging, turn on the CRT's debugging facilities
    // for checking for memory leaks
    // (we call _CrtSetDbgFlag in _tWinMain)
    #define _CRTDBG_MAP_ALLOC
    #include <stdlib.h>
    #include <crtdbg.h>
#endif

2. in the main procedure, include the _CrtSetDbgFlag like following:

int _tmain(int argc, _TCHAR* argv[])
{

    #ifdef _DEBUG
        ::_CrtSetDbgFlag( _CRTDBG_ALLOC_MEM_DF | _CRTDBG_LEAK_CHECK_DF );
    #endif

    std::auto_ptr<T> pT = new T;

That shouldn't compile, and only does due to a serious bug in VC8's
auto_ptr implementation. The bug is serious enough that you should
probably avoid using auto_ptr entirely until it is fixed, since it
allows erroneous code to compile, and then does weird things with that
code. The correct code is:

std::auto_ptr<T> pT(new T);

See
http://connect.microsoft.com/VisualStudio/feedback/ViewFeedback.aspx?FeedbackID=101842
and add your vote.

     //T* pT=new T;
    //*pShort = 100;

    return 0;
}

The program can complile,

And that's the problem.

Tom