__P macro

weixin_34355881

于 2012-02-28 15:18:00 发布

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原文链接：http://www.cnblogs.com/RichardLee/archive/2012/02/28/2371621.html

>     I have been reading the OpenBSD source code and have been running
> across some structures||Macros i'm not understanding. Where would i
> look for more explanition about the  __P Macros.

  This is historical code...
  
  Old pre-ANSI compilers didn't support prototypes for functions.
  
  __P(X) was defined as emptiness on these platforms, therefore, function
prototypes always looked like 'int function()' .

  On ANSI compilers, __P(X) is defined as X, so function prototypes were
properly defined as 'int function(int a, double b)' .

  The __P macro was traditionnaly used to provide portability on both type
of compilers.

  Best regards,
  
          -Frank.

转载于:https://www.cnblogs.com/RichardLee/archive/2012/02/28/2371621.html