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From: guy@sun.uucp (Guy Harris)
Newsgroups: net.lang.c,net.unix-wizards
Subject: Re: Re: how has C bitten you?
Message-ID: <2737@sun.uucp>
Date: Sat, 31-Aug-85 00:36:43 EDT
Article-I.D.: sun.2737
Posted: Sat Aug 31 00:36:43 1985
Date-Received: Sun, 1-Sep-85 06:03:13 EDT
References: <302@brl-tgr.ARPA> <471@baylor.UUCP>, <148@chinet.UUCP> <607@bu-cs.UUCP>
Organization: Sun Microsystems, Inc.
Lines: 46
Xref: watmath net.lang.c:6225 net.unix-wizards:14659

> Not really a bite, but I remember when I was first learning C
> I was quite bewildered by the fact that you couldn't really
> declare your own 'argv', that is, you couldn't declare an
> array of pointers to fixed length buffers except perhaps by:
> 
> char *myargv[] = {
> 	"\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0",
> 	"\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0",
> 
> 	etc
> 
> I mean, argv seemed kinda holy to me, disturbing.

If you want an array of pointers to fixed-length buffers, you can declare it
as long as the number of such pointers can be determined at the time you
write the code.

	char bufs[3][20];

	char *bufps[3] = {
		bufs[0],
		bufs[1],
		bufs[2],
	};

If the number can't be fixed when you write the code, you can set up "bufps"
at run time.

Also note that "argv" isn't a pointer to an array of pointers to fixed-length
buffers, it's a pointer to an array of pointers to strings, which you *can*
declare.

> P.S. I know argv is var length, but that would be even harder to declare!

The secret is that "argv" (or, more correctly, what "argv" points to)
*isn't* declared.  Pointers need not point to things which have been
declared; "malloc" returns pointers to objects fabricated on the fly.  If
you have "n" arguments ("n" is a variable here), just do

	register char **argv;

	argv = (char **)malloc(n * sizeof(char *));

And you can fill them in.

	Guy Harris