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From: dave@cs.arizona.edu (Dave P. Schaumann)
Newsgroups: comp.lang.c
Subject: Re: realloc((char *)NULL,size) - how standard ?
Message-ID: <941@caslon.cs.arizona.edu>
Date: 24 Feb 91 19:33:18 GMT
References: <1991Feb16.010828.2152@pscnet.UUCP> <1991Feb24.071716.409@athena.mit.edu> <15112:Feb2419:11:4391@kramden.acf.nyu.edu>
Organization: U of Arizona CS Dept, Tucson
Lines: 26

In article <15112:Feb2419:11:4391@kramden.acf.nyu.edu> brnstnd@kramden.acf.nyu.edu (Dan Bernstein) writes:
>In article <1991Feb24.071716.409@athena.mit.edu> scs@adam.mit.edu writes:
>>      Passing an initially-null pointer to realloc can make it very easy
>>      to write a self-starting incremental allocation algorithm.
>
>I find this advice counterproductive. [...]
>it is simply not portable. It's just as easy---and much more
>portable---to start by allocating one element.

Actually, if you want to port code that passes NULL to realloc to a machine
that doesn't like that, all you have to do is this:

void *Realloc( void *ptr, size_t size ) {

  if( ptr == NULL ) return malloc ( size ) ;
  else		    return realloc( ptr, size ) ;

} /* Realloc */

Then, just #define realloc Realloc anywhere you need to.  I was going to post
this when this question first came up, but I thought it was so obvious, it
would be a waste of bandwidth...

-- 
Dave Schaumann      | Is this question undecidable?
dave@cs.arizona.edu |