defining a 2D array with malloc and modifying it

Question

How do i define a 2D array using malloc ? (lets say 10X20).

second, can i increase number of rows or cols without creating a new increased array and copying all data

Answer 1

Although this is an old question, here is my different solution.

#include 
#include 
#include 

int main(int arvc, char* argv[])
{
    int (*a)[5][8];
    int i, j;

    a = (int (*)[5][8])calloc(5*8, sizeof(int));        
    for (i = 0; i < 5; i++) {
        for (j = 0; j < 8; j++)
            (*a)[i][j] = i *10 + j;
    }

    for (i = 0; i < 5; i++) {
        for (j = 0; j < 8; j++)
            printf("%d ", (*a)[i][j]);
        printf("\n");
    }

    return 0;
}

Compile and run

[user@buzz ~]$ gcc main.c -o main
[user@buzz ~]$
[user@buzz ~]$ ./main
0 1 2 3 4 5 6 7
10 11 12 13 14 15 16 17
20 21 22 23 24 25 26 27
30 31 32 33 34 35 36 37
40 41 42 43 44 45 46 47
[user@buzz ~]$