Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!mailrus!uflorida!ukma!rutgers!uwvax!oddjob!mimsy!chris
From: chris@mimsy.UUCP (Chris Torek)
Newsgroups: comp.lang.fortran
Subject: Re: Fortran versus C for numerical analysis
Message-ID: <13543@mimsy.UUCP>
Date: 14 Sep 88 01:35:17 GMT
References: <1484@ficc.uu.net> <3502@lanl.gov>
Organization: U of Maryland, Dept. of Computer Science, Coll. Pk., MD 20742
Lines: 34

>In article <1484@ficc.uu.net> peter@ficc.uu.net (Peter da Silva) writes:
>>You mean dynamically sized arrays. Dynamically allocated but statically
>>sized arrays are implemented like any other array.

In article <3502@lanl.gov>, jlg@lanl.gov (Jim Giles) writes:
>No, I've never seen a C dynamically allocated multidimensional array
>that wasn't implemented as an array of pointers.  For a two dimensional
>array, each pointer in the array of pointers points to a row of the array.
>Higher dimensions are implementes as pointers_to_pointers_to_....
>the number of indirect levels is one less than the number of dimensions.
>
>- This is _NOT_ 'like any other array'.

You seem to have conveniently forgotten the material I posted here not
long ago.  Here is a dynamic (fixed size) array that is not an array of
pointers:

	extern char *malloc();

	f()
	{
		double (*arr)[64];
		int n_rows = 16, i, j;

		arr = (double (*)[64])malloc(n_rows * sizeof(*arr));
		if (arr == NULL) ... do something

		for (i = 0; i < n_rows; i++)
			for (j = 0; j < 64; j++)
				/* work on arr[i][j] */;
	}
-- 
In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 7163)
Domain:	chris@mimsy.umd.edu	Path:	uunet!mimsy!chris