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From: eklhad@ihnet.UUCP (K. A. Dahlke)
Newsgroups: net.lang.c
Subject: Re: malloc(array[][][]), two methods
Message-ID: <158@ihnet.UUCP>
Date: Fri, 7-Sep-84 14:41:13 EDT
Article-I.D.: ihnet.158
Posted: Fri Sep  7 14:41:13 1984
Date-Received: Wed, 12-Sep-84 03:04:16 EDT
Organization: AT&T Bell Labs, Naperville, IL
Lines: 38

I once had to malloc() a 3-dimensional table.
The code was not proprietary, so here is a fragment.

mktbl(){
unsigned short (*freq)[ASIZE][ASIZE];

/* malloc a 3-dimensional table of triple frequencies */
freq = (unsigned short ***)
malloc(sizeof(unsigned short)*ASIZE*ASIZE*ASIZE);
for(i=0;i<ASIZE*ASIZE*ASIZE;++i)
freq[0][0][i]=0;
...
++freq[c1][c2][c3];
...
}

When I asked a structured programmer how to solve this malloc problem,
the answer was immediate and predictable.
"put the array in a structure."
struct FOO {
unsigned short freq[ASIZE][ASIZE][ASIZE];
} *foo;
mktbl(){
/* malloc a 3-dimensional table of triple frequencies */
foo = (struct FOO*)
malloc(sizeof(unsigned short)*ASIZE*ASIZE*ASIZE);
for(i=0;i<ASIZE*ASIZE*ASIZE;++i)
foo->freq[0][0][i]=0;
...
++(foo->freq[c1][c2][c3]);
...
}

The foo-> stuff is annoying to type,
but the structures are simpler to understand, and more portable.
-- 

Karl Dahlke    ihnp4!ihnet!eklhad