Q79845: INFO: Old Style (K&R) Declarations Are Not Supported in C++

Article: Q79845
Product(s): Microsoft C Compiler
Version(s): 1.0,1.5,2.0,2.1,4.0,5.0
Operating System(s): 
Keyword(s): kbLangCPP kbVC100 kbVC150 kbVC200 kbVC210 kbVC400 kbVC500
Last Modified: 24-JUN-2002

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The information in this article applies to:

- Microsoft Visual C++ for Windows, 16-bit edition, versions 1.0, 1.5 
- Microsoft Visual C++, 32-bit Editions, versions 1.0, 2.0, 2.1, 4.0, 5.0 
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SUMMARY
=======

The Microsoft C/C++ Compiler versions 7.0 and later do not support Old Style
function declarations in C++ files. Old Style declarations are still supported
in C files.

Old Style declarations, sometimes called K&R declarations, are declarations
in which there are no parameters listed inside the parentheses. For example:

  void KRfunc();  /* declaration */ 
  void KRfunc(a, b)   /* definition */ 
  int a;
  char b;
  { }

C++ requires ANSI-style function prototypes (or declarations), which list the
type of each parameter accepted by the function, as shown here:

     void ANSIfunc(int a, char b);

This type of declaration is required because in C++ each function has a
signature. The signature consists of the name of the function and the types of
the parameters it accepts. The compiler cannot construct the signature of a
function from the K&R declaration.

REFERENCES
==========

For more information about parameter lists in function declarations and how
these are handled by C and C++, please see the following article in the
Microsoft Knowledge Base:

  Q94579 Creating a Function Pointer to a C++ Member Function

Additional query words:

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Keywords          : kbLangCPP kbVC100 kbVC150 kbVC200 kbVC210 kbVC400 kbVC500 
Technology        : kbVCsearch kbVC400 kbAudDeveloper kbvc150 kbvc100 kbVC500 kbVC200 kbVC210 kbVC32bitSearch kbVC16bitSearch kbVC500Search
Version           : :1.0,1.5,2.0,2.1,4.0,5.0
Issue type        : kbinfo

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