Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ncar!asuvax!noao!arizona!sunquest!ggg
From: ggg@sunquest.UUCP (Guy Greenwald)
Newsgroups: comp.lang.c
Subject: Re: problem with cc compiler
Summary: Hide the duplicate RTL declaration
Message-ID: <175@sunquest.UUCP>
Date: 27 Jul 89 19:23:43 GMT
References: <712@unsvax.NEVADA.EDU> <10589@smoke.BRL.MIL> <4935@alvin.mcnc.org>
Organization: Sunquest Information Systems, Tucson
Lines: 30

In article <4935@alvin.mcnc.org>, spl@mcnc.org (Steve Lamont) writes:
> Suppose that I wish to implement my own math library function, say sin() or
> cos(), for whatever reason, in a large pre-existing piece of code that I don't
> want to fiddle too much with.  How would I do this, then?

Declare the routine name before it is invoked, then define the routine to be
static. Here's an example:

main()
{
	/* Declare the function here */
	double sin();
	double x, something;

	/* ... code ... */

	x = sin(something);
}

static double sin(angle)
double angle;
{
	double value;

	/* Steve's slick sine calculation */
	return value;
}

It is the combination of the static definition and the declaration before use
that avoids the problem with the duplicate name in the run-time library.