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From: ark@alice.UucP (Andrew Koenig)
Newsgroups: net.unix,net.unix-wizards,net.arch,net.lang.c
Subject: Re: get size of malloc'd object
Message-ID: <5699@alice.uUCp>
Date: Mon, 23-Jun-86 22:23:14 EDT
Article-I.D.: alice.5699
Posted: Mon Jun 23 22:23:14 1986
Date-Received: Wed, 25-Jun-86 04:46:30 EDT
References: <2216@peora.UUCP>
Organization: Bell Labs, Murray Hill
Lines: 28
Xref: watmath net.unix:8363 net.unix-wizards:18582 net.arch:3558 net.lang.c:9566

There is a very simple way to do this portably:

	struct chunk {
		unsigned size;
		char *mem;
	};

	struct chunk
	challoc (n)
		unsigned n;
	{
		struct chunk ch;
		ch.size = n;
		ch.mem = malloc (n);
		return ch;
	}

	void
	chfree (ch)
		struct chunk ch;
	{
		if (ch.mem)
			free (ch.mem);
	}

Now rewrite your program to deal with memory through chunk structures
instead of through simple pointers.  It should be possible to make this
easier by using macros.