Thread: dynamic mem alloc of 2-d arrays

So, anyone know how to create a 2-d array using calloc? It seems to have been overlooked in my book.

You could make an array of pointers and let each element be an array.

http://www.cs.cf.ac.uk/Dave/C/node11...00000000000000

Like so

Code:

#include <stdio.h>
#include <stdlib.h>

#define ROWS    5
#define COLS    20

int main ( ) {
    int test[ROWS][COLS];
    int **p;
    int row, col;

    /* allocate it */
    p = calloc( ROWS, sizeof(int*) );
    for ( row = 0 ; row < ROWS ; row++ ) {
        p[row] = calloc( COLS, sizeof(int) );
    }

    /* use it */
    for ( row = 0 ; row < ROWS ; row++ ) {
        for ( col = 0 ; col < COLS ; col++ ) {
            test[row][col] = p[row][col];
        }
    }
    /* free it */
    for ( row = 0 ; row < ROWS ; row++ ) {
        free(p[row]);
    }
    free(p);

    return 0;
}

OK, I thought there would be a nice easy command to do it, but I guess not.
thanks for your help...

The key word there is actually command (singular)

> The key word there is actually command
There is a one-liner, but it only works if COLS is a compile-time constant.

Perhaps you were thinking of some bloat language which does everything for you.

At some point, you've got to get into it at start doing things for yourself.