Path: utzoo!mnetor!uunet!husc6!hao!ames!pasteur!ucbvax!cbosgd!cbdkc1!pmd
From: pmd@cbdkc1.ATT.COM (Paul Dubuc)
Newsgroups: comp.lang.c
Subject: Re: Allocating a two-dimensional array
Message-ID: <2766@cbdkc1.ATT.COM>
Date: 18 Jan 88 20:40:09 GMT
References: <1050@ogg.cgrg.ohio-state.edu>
Reply-To: pmd@cbdkc1.UUCP (Paul Dubuc)
Organization: AT&T Bell Laboratories; Columbus, Ohio
Lines: 23

In article <1050@ogg.cgrg.ohio-state.edu> 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.

First allocate an array of N pointers to N arrays of floats, then
allocate N arrays of N floats and assign the resulting pointers to
the elements of the first array.

float **fa;

fa = (float **)calloc(N, sizeof(float *));
for(i=0;i<N;++i) fa[i] = (float *)calloc(N, sizeof(float));

Now "fa" is your matrix.  When you want to free the space 

for(i=0;i<N;++i) free((char *)fa[i]);
free((char *)fa);

-- 

Paul Dubuc	{ihnp4,cbosgd}!cbdkc1!pmd