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Q135630: DOC: Incorrect Prototype & Memory Allocation for PX_Blob

Article: Q135630
Product(s): Microsoft C Compiler
Version(s): winnt:
Operating System(s): 
Keyword(s): kbole kbdocfix kbCtrl
Last Modified: 02-AUG-2001

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The information in this article applies to:

- The Microsoft Foundation Classes (MFC), included with:
   - Microsoft OLE Control Developer's Kit (CDK), versions 1.0, 1.1, 1.2 
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SUMMARY
=======

The documentation for the prototype of PX_Blob in the CDK Books Online is shown
incorrectly as:

     BOOL PX_Blob( CPropExchange* pPX, LPCTSTR pszPropName,
   
        HGLOBAL*& hBlob, HGLOBAL hBlobDefault = NULL );

The actual prototype as shown in the CDK source code in Afxctl.h is:

     BOOL PX_Blob(CPropExchange* pPX, LPCTSTR pszPropName, HGLOBAL& hBlob,
   
        HGLOBAL hBlobDefault = NULL);

MORE INFORMATION
================

Note that the third parameter is incorrectly listed as HGLOBAL*& hBlob in
the documentation and should instead be HGLOBAL& hBlob as shown in the
actual prototype.

There is also another error in the PX_Blob remarks section of the documentation.
It states the following incorrect information:

  Note that PX_Blob will allocate memory, using the new operator, when loading
  BLOB-type properties. Therefore, the destructor of your control should call
  delete on any BLOB-type property pointers to free up any memory allocated to
  your control.

This correct documentation should be as follows:

  Note that PX_Blob will allocate memory, using the Windows GlobalAlloc API,
  when loading BLOB-type properties. You are responsible for freeing this
  memory. Therefore, the destructor of your control should call GlobalFree on
  any BLOB-type property handles to free up any memory allocated to your
  control.

The problems described in this article were fixed in Visual C++, 32-bit edition,
version 4.0 and later.

Additional query words: 1.50 1.51 1.52 2.00 2.10 2.20 4.00

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Keywords          : kbole kbdocfix kbCtrl 
Technology        : kbAudDeveloper kbMFC
Version           : winnt:

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