Path: utzoo!utgpu!water!watmath!clyde!rutgers!sdcsvax!ucsdhub!esosun!seismo!uunet!mcvax!nikhefh!n62
From: n62@nikhefh.hep.nl (Klamer Schutte)
Newsgroups: comp.lang.c
Subject: Allocating two dimensional arrays
Message-ID: <419@nikhefh.hep.nl>
Date: 20 Jan 88 12:06:25 GMT
Reply-To: n62@nikhefh.hep.nl (Klamer Schutte)
Organization: Nikhef-H, Amsterdam (the Netherlands).
Lines: 28


>Spencer@ogg.cgrg.ohio-state.edu (PROCEED) writes:
>>Maybe this can't be done.  Maybe I'm not thinking about it the right way.
>>But I can't figure out how to dynamically allocate a two-dimensional 
>>array of floats.  (I have to have an N by N matrix of floats, but don't
>>know N beforehand.)  Can anyone help me on this one?  Thanks.
 
and as a proposed solution:

>#define malloc_matrix(p,n,m,t) ((p) = ((t) *) malloc((n)*(m)*sizeof(t)))
>#define matrix(p,n,m,x,y)      ((p)[(n)*(x)+(y)])

Why not simple something like this:

struct matrix
{	float	data[n][m];
}	*foo;

...

foo = ( struct matrix * )malloc( sizeof( struct matrix ));

and accessing the data like:

foo->data[n][m];

In this way the source code will reflect ecxactly how the data is accessed;
I think C programming should be done that way.