BUG: Memory leaks when you use the CWnd class versions of the GetDC method and the ReleaseDC method (819635)


The information in this article applies to:

  • Microsoft eMbedded Visual C++, Version:4.0

SYMPTOMS

When you run code that calls the CWnd::GetDC function followed by the CWnd::ReleaseDC function, a memory leak of 4 bytes occurs.

CAUSE

The cause of this bug is currently unknown.

RESOLUTION

To avoid this problem, do not use the CWnd class versions of the GetDC method and the ReleaseDC method. Use the GetDC function and the ReleaseDC function.

STATUS

Microsoft has confirmed that this is a bug in the Microsoft products that are listed at the beginning of this article.

MORE INFORMATION

Steps to Reproduce the Behavior

In a method that is a part of a class that is derived from CWnd, insert the following code in your application:

CDC *pDC;
    RECT rect;

    GetClientRect (&rect);

    for (int i = 0; i < 1000; i++)
    {
        pDC = GetDC ();
        ReleaseDC (pDC);
  }
If you run this code and then check the system memory before and after you run the code, you notice that the system memory leaks four bytes per iteration. If you change the code to the following code, the memory leak does not occur:
HDC hDC;
       RECT rect;
    ::GetClientRect (m_hWnd, &rect);

    for (int i = 0; i < 1000; i++)
    {
        hDC = ::GetDC (m_hWnd);
        ::DrawText (hDC, L"Testing...", 10, &rect, DT_CENTER);
        ::ReleaseDC (m_hWnd, hDC);
    }
Modification Type:MinorLast Reviewed:3/25/2004
Keywords:kbpending kbbug KB819635 kbAudDeveloper kbAudITPRO kbAudOEM
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