NetNews Usenet Archive 1992 #27/NN_1992_27.iso/spool/comp/lang/c/16719

Text File | 1992-11-18 | 1.7 KB | 55 lines

Newsgroups: comp.lang.c
Path: sparky!uunet!comp.vuw.ac.nz!actrix!David.Empson
From: [e-mail]
Subject: Re: 2-D Arrays, Revisited.
Organization: Actrix Information Exchange
Date: Wed, 18 Nov 1992 12:23:42 GMT
Message-ID: <[e-mail]>
References: <[e-mail]>
Sender: [e-mail] (David Empson)
Lines: 43

In article <[e-mail]> [e-mail] (Fahad A Hoymany) writes:
> I am writing a function that should accept a 2-D array (hopefully of any
> size), operate on that array, and returns 'anything' to the caller. Please
> don't suggest I use double pointers because I do not want to restrict the
> users of my function to use them when they are used to declaring arrays
> as : int a[2][5].
>
> What should the formal parameters line look like?

int my_array_function(int a[][5], int nrows) {
    /* ... */
}

You can refer to array elements within the function as normal, e.g.
a[i][j] will refer to the ith row and jth column.

The function should be called with the name of a compatible array.


In C, only the leftmost dimension can be left unspecified.  All other
dimensions must be fixed.  If you want a 2-D array that varies in both
dimensions, you will have to do something rather more ugly, e.g.:

int another_array_function(int a[], int nrows, int ncols) {
    /* To refer to element a[i][j], use: */
    temp = a[i * ncols + j];
}

and to call this function, given an array b[10][2], you would use:

    temp = another_array_function(b[0], 10, 2);

or

    temp = another_array_function(&b[0][0], 10, 2);


Hope this helps.
--
David Empson

Internet: [e-mail]    [e-mail]
Snail mail: P.O. Box 27-103, Wellington, New Zealand