Newsgroups: comp.lang.c
Path: utzoo!henry
From: henry@zoo.toronto.edu (Henry Spencer)
Subject: Re: prototyping (oh no! not again??)
Message-ID: <1990Nov27.163716.23883@zoo.toronto.edu>
Organization: U of Toronto Zoology
References: <DAVIS.90Nov26144044@pacific.mps.ohio-state.edu>
Date: Tue, 27 Nov 90 16:37:16 GMT

In article <DAVIS.90Nov26144044@pacific.mps.ohio-state.edu> davis@pacific.mps.ohio-state.edu  (John E. Davis) writes:
>   I have a function that takes a 2-d array of unknown dimension and does
>   things with it.  How do I declare and call it?

You can't do this in C.  Period.  Indexing into the array requires knowing
the size of the rows in the array.  C insists on knowing this at compile time,
so the second dimension must be declared as a specific number.  The only way
out of this is to pass a pointer to the array as if it were one-dimensional,
and do the indexing arithmetic yourself.

>   I tried this:
>   double trace(double **matrix, int dim)

Sigh.  Please see any good C textbook for the differences between pointers
and arrays.  This is wrong no matter what shape your array has.
-- 
"I'm not sure it's possible            | Henry Spencer at U of Toronto Zoology
to explain how X works."               |  henry@zoo.toronto.edu   utzoo!henry