Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!umich!samsung!uunet!virtech!cpcahil
From: cpcahil@virtech.uucp (Conor P. Cahill)
Newsgroups: comp.lang.c
Subject: Re: index and rindex question...
Message-ID: <1990Feb1.124228.15878@virtech.uucp>
Date: 1 Feb 90 12:42:28 GMT
References: <11716.25C6818B@urchin.fidonet.org>
Reply-To: cpcahil@virtech.UUCP (Conor P. Cahill)
Organization: Virtual Technologies Inc., Sterling VA
Lines: 35

In article <11716.25C6818B@urchin.fidonet.org> Bob.Stout@p6.f506.n106.z1.fidonet.org (Bob Stout) writes:
>In an article of <27 Jan 90 02:04:19 GMT>, (Conor P. Cahill) writes:
>
> >They are equivalent to the system V functions strchr() and strrchr(),
> >respectively.
>
>  Both the strchr() and strrchr() functions made it into the ANSI spec while  
>index() and rindex() didn't. I believe this was because the latter two  
>functions on some systems return an int offset of the character rather than a  
>pointer to it. Based on this usage, I use:

The original poster has asked about the "BSD" functions index() and rindex().
The documentation as far back as 4.1BSD shows that they are the equivalent
to strchr()/strrchr() (i.e. they return pointer to char).

>#define index(s,c)  ((strchr((s),(c))) ? (size_t)(strchr((s),(c))-(s)) : -1)
>#define rindex(s,c) ((strrchr((s),(c))) ? (size_t)(strrchr((s),(c))-(s)) : -1)

This would work to replace index() only when the original software came
from a system that did not use the BSD implementation.  I would guess that
it would be rather rare today. If I remember correctly, PWB Unix had an
index() that returned int.

For most of the code that you run into today (yes, I know that there are
still V6 and PWB systems around, in fact I work on one every once in a 
while) the following defines will suffice:

	#define index(s,c)	strchr(s,c)
	#define rindex(s,c)	strrchr(s,c)

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| Conor P. Cahill     uunet!virtech!cpcahil      	703-430-9247	!
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