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From: bph@buengc.BU.EDU (Blair P. Houghton)
Newsgroups: comp.lang.c
Subject: Re: free (NULL);
Message-ID: <5798@buengc.BU.EDU>
Date: 8 May 90 20:24:56 GMT
References: <1194@wet.UUCP>
Reply-To: bph@buengc.bu.edu (Blair P. Houghton)
Followup-To: comp.lang.c
Organization: Boston Univ. Col. of Eng.
Lines: 19

In article <1194@wet.UUCP> noah@wet.UUCP (Noah Spurrier) writes:
>
>Is there anything wrong with freeing a NULL? pointer? I have a function that

In ANSI C, doing `free(ptr)', "if ptr is a NULL pointer, no action
occurs" (quoted from X3.159-1989).

Most current free(3) manual pages seem to ignore this bit of
semantics, though you might get stuck on things like "the
argument to free is a pointer to a block of memory previously
allocated by malloc()."

ANSI instead says that if it doesn't match a *alloc'ed pointer
it has undefined consequences, except of course for the explicit
case where the pointer is NULL.

				--Blair
				  "Let's get Mikey to program it.
				   Yeah, he hates everything..."