Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!usc!srhqla!demott!kdq
From: kdq@demott.COM (Kevin D. Quitt)
Newsgroups: comp.lang.c
Subject: Re: Just a minor new twist on free()
Message-ID: <629@demott.COM>
Date: 2 Oct 90 15:39:43 GMT
References: <PDS.90Oct1095707@lemming.webo.dg.com>
Reply-To: kdq@demott.COM (Kevin D. Quitt)
Organization: DeMott Electronics Co., Van Nuys CA
Lines: 29

In article <PDS.90Oct1095707@lemming.webo.dg.com> pds@lemming.webo.dg.com (Paul D. Smith) writes:
>In article <7365@darkstar.ucsc.edu> funkstr@ucscb.ucsc.edu (Larry Hastings) writes:
>
>
>[] #define smart_free(x) { if (x != NULL) { free(x); x = NULL; } }
>
>
>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).
>
>So, you could save yourself some execution time (if you have an ANSI
>compiler) by writing:
>
>#define smart_free(x) { free(x); x = NULL; }
>

    Actually, execution time will be saved by the original definition,
since it avoids the call/return overhead in invoking free when the
pointer is null.  This was discussed a month or so ago, and timings were
published. 

-- 
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Kevin D. Quitt         demott!kdq   kdq@demott.com
DeMott Electronics Co. 14707 Keswick St.   Van Nuys, CA 91405-1266
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