Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!usc!orion.oac.uci.edu!eapu034
From: eapu034@orion.oac.uci.edu (Carl F. Edman)
Newsgroups: comp.lang.c++
Subject: Re: parameter[][]
Message-ID: <26B9BF5A.7291@orion.oac.uci.edu>
Date: 3 Aug 90 18:15:53 GMT
References: <1545@m1.cs.man.ac.uk>
Reply-To: eapu034@orion.oac.uci.edu (Carl F. Edman)
Organization: University of California, Irvine
Lines: 35

In article <1545@m1.cs.man.ac.uk> jk@cs.man.ac.uk (John Kewley ICL) writes:
>One of our staff is whingeing about having to specify the size of all
>dimensions for a multidimensional array (beyond the first that is).
>
>Can anyone give me some good reasons why this is, so I can placate him.
>He claims that it can be done in C so why can't it be done in C++.
>--
>        J.K.
> 
For starters: This is in no way possible in C or C++ and couldn't be
as the following example might illustrate.

In one source-file:

char array[4][6][8];

In another source-file:

extern char array[][][];        // Using NO dimensional specifiers
array[3][5][7]='a';

Now, how should the compiler of the second source-file find out where
element a[3][5][7] is in respect to the base-address pointed to by a,
without knowing the dimensions of the array ?
In the example the element would be the (3*6+5)*8+7st (counting from zero)
of the array. As you see the knowing the exact dimensions of the array
is neccessary for the second file to compile thus: No there is no way
to use a declaration like the one above.

	Carl Edman

Theorectial Physicist,N.:A physicist whose   | Send mail
existence is postulated, to make the numbers |  to
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