Date: Thu, 5 Oct 2000 08:05:07 +0200 (IST)
From: Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>
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To: Michael Powe <michael+netscape AT trollope DOT org>
cc: djgpp AT delorie DOT com
Subject: Re: problem with math.h
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On Wed, 4 Oct 2000, Michael Powe wrote:

> gcc -Wall -ansi -pedantic ... -lm 
> 
> results in an error that `PI' is undeclared.

This is the expected behavior.

> Looking in math.h, I see that the section in which PI is #defined is
> preceded by #ifndef __STRICT_ANSI__ and #ifndef _POSIX_SOURCE.  
> 
> Does ANSI C exclude a value for PI?

Yes, the ANSI Standard does not define any macro to get the value of Pi.  
Since PI and M_PI pollute the namespace (they do not begin with an 
underscore), they are made invisible with -ansi.

Portable programs which comply to ANSI C should provide their own 
definitions of Pi.  You could simply copy the value from math.h.