Q51198: INFO: Formal Parameters Default to Type int

Article: Q51198
Product(s): Microsoft C Compiler
Version(s): MS- DOS:6.0,6.00a,6.00ax,7.0;OS/2:6.0,6.00a;WIN3X:1.0,1.5;WINNT:1.0,2.0,4.0,5.0 ;
Operating System(s): 
Keyword(s): kbCompiler kbVC100 kbVC150 kbVC200 kbVC400 kbVC500 kbVC600
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++ for Windows, 16-bit edition, versions 1.0, 1.5 
   - Microsoft Visual C++, 32-bit Editions, versions 1.0, 2.0, 4.0, 5.0 
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SUMMARY
=======

In Microsoft C, a function declaration such as the following does not generate a
compiler error even though the variable "voida" is not referenced:

     void main (voida)
     {
     }

NOTE: This is true only for the C compiler, not the C++ compiler.

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

The C and QuickC compilers do not generate an error because the variable "voida"
defaults to a variable of type int. The compilers understand the above function
definition because they recognize the "old style" of ANSI C declarations as well
as the new. In general, the equivalents of the above code are as follows:

  Old Style                           New Style
  ---------                           ---------

  void function (voida)               void function (int voida)
  int voida; <- default if missing    {
  {                                   }
  }


Please refer to "The C Programming Language" by Brian Kernighan and Dennis
Ritchie for a discussion on differences between old and new style with regards
to function definition.

Additional query words: 8.00 8.00c 9.00

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Keywords          : kbCompiler kbVC100 kbVC150 kbVC200 kbVC400 kbVC500 kbVC600 
Technology        : kbVCsearch kbAudDeveloper kbCVCComp
Version           : MS- DOS:6.0,6.00a,6.00ax,7.0;OS/2:6.0,6.00a;WIN3X:1.0,1.5;WINNT:1.0,2.0,4.0,5.0 ;

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