Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!tut.cis.ohio-state.edu!gem.mps.ohio-state.edu!ginosko!uunet!telxon!gorpong
From: gorpong@telxon.uucp (Gordon C. Galligher)
Newsgroups: comp.lang.c
Subject: Re: Question: malloc on 2-d array
Summary: Try calloc() or malloc(dim * sizeof(...))
Keywords: malloc, 2-d array
Message-ID: <70@telxon.UUCP>
Date: 11 Jul 89 16:23:30 GMT
References: <15372@eecae.UUCP>
Sender: news@telxon.UUCP
Reply-To: gorpong@telxon.UUCP (Gordon C. Galligher)
Distribution: usa
Organization: Telxon Corporation, Akron Ohio (NNTP with a :-)
Lines: 33

In article <15372@eecae.UUCP> pantz@brain.mth.msu.edu writes:
>
>Does anyone know how I can allocate memory space for a multi-dimensional
>array?  Thanks in advance.

(In the following examples, you can substiture your favorite pointer in 
place of the char *'s):

On some systems the calloc() call is allowed.  You declare a variable:

	char **a, *calloc();
	
	if ( (a = (char **) calloc(25, sizeof(char *))) == NULL )
		error_message_here;

This will allocate at least enough memory to be used like an array of 25 
elements, each element being a pointer to a character.  To put strings INTO 
these places, then you need to call malloc() for each a[x] you want to store.

If calloc() doesn't exist, then you can coerce malloc() into doing it for you:

	char **a, *malloc();
	
	if ( (a = (char **) malloc((25 * sizeof(char *)))) == NULL )
		error_message_here;

Again, the malloc() for each a[x] is needed.

		-- Gordon.
Gordon C. Galligher  <|> ...!uunet!telxon!gorpong <|> gorpong@telxon.uucp.uu.net
Telxon Corporation   <|> "Admit it, ve're lost!"  - Checkov  "Alright, we're 
Akron, Ohio, 44313   <|>  lost, but we're making great time."  - Sulu
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