malloc-ating multidimensional array in function

Question

I\'m trying to allocate a 2d array in a C program. It works fine in the main function like this (as explained here):

#include 
#include 

        

Answer 1

Here is your function, fixed:

int malloc2d(int *** grid, int nrows, int ncols){
    int i;
    *grid = (int**)malloc( sizeof(int *) * nrows);

    if (*grid == NULL){
        printf("ERROR: out of memory\n");
        return 1;
    }

    for (i=0;i<nrows;i++){

        (*grid)[i] = (int*)malloc( sizeof(int) * ncols);
        if ((*grid)[i] == NULL){
            printf("ERROR: out of memory\n");
            return 1;
        }
    }
    printf("Allocated!\n");
    return 0;
}

int main(int argc, char ** argv)
{
    int ** grid;

    malloc2d(&grid, 10, 10);
    grid[5][6] = 15;
    printf("%d\n", grid[5][6]);
    return 0;
}

Note the function now recieves an int*** and you pass the address of your int** to the function. The function then dereferences the int*** to put the address of the allocated memory block in it.