feng@caen.engin.umich.edu (Liqiang Feng) (10/31/90)
I am trying to dynamically allocate a 2-D array, and I think I need to declear a pointer which is the pointer to an array of pointers, and the pointers in that array of pointers will serve as the pointers to the 2-D array. Is this right? Can anybody give me a very simple example how it is done? Thank you very much. E-mail: feng@caen.engin.umich.edu
karl@haddock.ima.isc.com (Karl Heuer) (10/31/90)
>I am trying to dynamically allocate a 2-D array...
I have mailed the FAQ to this person; others who have the same problem can
wait for the next repost on the first of the month. I am posting this note in
a vain attempt to stop the redundant discussion before it starts.
Karl W. Z. Heuer (karl@ima.isc.com or uunet!ima!karl), The Walking Lintron@argus.lpl.arizona.edu (Ron Watkins) (10/31/90)
If your question is how to declare such a beastie, try this on for size: (please note that im just typing this in from my head not from some existing piece of code); int i; DTYPE ** foo; ... foo = (DTYPE **) malloc (NAXIS2 * sizeof (DTYPE *)); for (i = 0; i < NAXIS2; i++) foo[i] = (DTYPE *) malloc (NAXIS1 * sizeof (DTYPE)); /* OR */ * (foo + i) = (DTYPE *) malloc (NAXIS1 * sizeof (DTYPE)); Where: 1) DTYPE is your data type of interest. If you want multiple data type capability, good luck. Maybe someone would be kind enough to enlighten both of us on that one. 2) NAXIS1 is the fastest axis (note that you can't go zipping through this two dimensional space with a pointer dereference like when you normally declare 2-D arrays). 3) NAXIS2 is the slower axis (presumably y?). I supplied to different approaches for the body of the for loop. Please don't use BOTH of them. :-) P.S. If I have totally screwed this thing up, no flames please. Just nicely tell me that I should go crawl under a rock! Oh and while your doing that, please do send a proper response to the question at hand. _ PEACE! / | \ Ron Watkins / | \ ron@argus.lpl.arizona.edu ( /|\ ) \ / | \ / \ | /