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Q41374: Assignment of Void Pointer Does Not Give Warning Message

Article: Q41374
Product(s): Microsoft C Compiler
Version(s): 1.0,1.5,1.51,2.0,2.1,6.0,6.0a,6.0ax
Operating System(s): 
Keyword(s): 
Last Modified: 25-JUL-2001

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The information in this article applies to:

- Microsoft C/C++ Compiler (CL.EXE), included with:
   - Microsoft C for MS-DOS, versions 6.0, 6.0a, 6.0ax 
   - Microsoft C for OS/2, versions 6.0, 6.0a 
   - Microsoft C/C++ for MS-DOS, version 7.0 
   - Microsoft Visual C++, versions 1.0, 1.5, 1.51 
   - *EDITOR Please do not choose this product*Microsoft Visual C++ 32-bit Edition* use 241, 265, 225, versions 1.0, 2.0, 2.1 
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SUMMARY
=======

The Sample Code below shows an inconsistency with the way that the Microsoft
compilers listed above deal with pointer checking. The ANSI standard is unclear
about whether an assignment to a void pointer should be checked to see if it is
being assigned a nonpointer variable. The code below shows that character
pointers are checked while void pointers are not; the code will generate the
following warnings:

16-bit compilers
----------------

The compiler generates the following warning for the void pointer in the sample
code as well as the character pointer:

     C4047: '=' different levels of indirection

32-bit compilers
----------------

The compiler generates the following warming with the sample code:

     C4047: "=": 'void *' differs in levels of indirection from 'int'

7.0 and later
-------------

Compiler versions 7.0 and later generate the following error in both cases if the
program is compiled as a C++ program (.cpp extension).

  error C2446: '=' : no conversion from 'int ' to 'void *'

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

Sample Code:
------------

  /* Compile options needed: none
  */ 

  int i;         /* i could be float, double, char, long, or unsigned */ 
  char *p;
  void *v;

  void main()
  {
     p = i;      /* This will give a warning message */ 
     v = i;
  }

Additional query words: kbinf 6.00 6.00a 6.00ax 7.00 8.00 8.00c 9.00 9.10 1.00 1.50 2.00 2.10

======================================================================
Keywords          :  
Technology        : kbVCsearch kbAudDeveloper kbCVCComp
Version           : :1.0,1.5,1.51,2.0,2.1,6.0,6.0a,6.0ax

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