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From: henry@utzoo.UUCP (Henry Spencer)
Newsgroups: net.lang.c
Subject: Re: how has C bitten you?
Message-ID: <5932@utzoo.UUCP>
Date: Fri, 6-Sep-85 12:32:41 EDT
Article-I.D.: utzoo.5932
Posted: Fri Sep  6 12:32:41 1985
Date-Received: Fri, 6-Sep-85 12:32:41 EDT
References: <228@investor.UUCP> <132@mcgill-vision.UUCP> <2702@sun.uucp>, <797@kuling.UUCP>
Organization: U of Toronto Zoology
Lines: 17

> Is it also possible to give a NULL-pointer to a procedure as a parameter,
> if for example the procedure would return several values, and we are not
> interested in all of them?
> 
> wait(0) works at least here (4.2BSD), but something like this does not:
> ...
> 	(void)read(fd, 0, n);

Passing NULL only works if the function is prepared for the possibility
and explicitly checks for it.  wait() does; read() does not.  See the
documentation.  By the way, that should be "wait( (int *)0 )", to make
sure the type is right; the Unix documentation is often sloppy about this
particular detail, since it originated on machines where the sloppiness
didn't cause any problems.
-- 
				Henry Spencer @ U of Toronto Zoology
				{allegra,ihnp4,linus,decvax}!utzoo!henry