From: Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>
Newsgroups: comp.os.msdos.djgpp
Subject: Re: make depend
Date: Wed, 19 Jan 2000 11:46:40 +0200
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On Tue, 18 Jan 2000, Damian Yerrick wrote:

> >the ANSI Standard
> 
> does not define the behavior of __DJGPP__.

No, but it does define general rules for interoperability between the
compiler and the library, including the header files.

> >says that a program which doesn't include any header files
> >should still have the same behavior as when it does.
> 
> How would certain programs work without math.h?

Exactly like they did before ANSI C invented the prototypes: you need
to put either the definition of a function or its protoype before you
use it.  The prototype doesn't *have* to come from a header file.

But while you can require this for standard functions like sin and
atan2, it's unreasonable to do that for library-private symbols like
__DJGPP__.

Incidentally, stdio.h doesn't include any functions that take floats
or doubles, so you can easily write a program that doesn't include
stdio.h and still works perfectly.  Most of the functions in stdio.h
(those which return an int or a void) don't need a prototype to work
correctly.