Path: utzoo!attcan!uunet!pilchuck!dataio!fnx!nazgul!bright
From: bright@nazgul.UUCP (Walter Bright)
Newsgroups: comp.lang.c
Subject: Re: Just a minor new twist on free()
Message-ID: <117@nazgul.UUCP>
Date: 24 Oct 90 22:21:49 GMT
References: <7365@darkstar.ucsc.edu> <PDS.90Oct1095707@lemming.webo.dg.com> <1990Oct02.132313.6659@virtech.uucp>
Reply-To: bright@nazgul.UUCP (Walter Bright)
Organization: Zortech, Seattle
Lines: 21

In article <1990Oct02.132313.6659@virtech.uucp> cpcahil@virtech.UUCP (Conor P. Cahill) writes:
<In article <PDS.90Oct1095707@lemming.webo.dg.com> pds@lemming.webo.dg.com (Paul D. Smith) writes:
<<It should be pointed out that in ANSI C free(NULL) is defined, and is
<<legal (any conforming implementation of free() must ignore being
<<passed a NULL pointer).
<While this is a true statement, I would never recommend that one take advantage
<of this feature.  If you know the variable is NULL don't pass it to free.
<The performance cost of the following statement:
<		if( ptr != NULL )
<			free(ptr);
<as opposed to:
<		free(ptr);
<will be unmeasurable in most, if not all, circumstances.  In addition, by
<adding the if() you get code that is portable across all implementations.


I'd prefer to use, on non-conforming implementations of free():

    #if NONCONFORMINGFREE
    #define free(p)	((p) && free(p))
    #endif