[C] What is wrong with this code??

[Znupi]

Really basic code. It allocates memory for a nxn two-dimensional array and *tries* to fill it out with zeros:

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

int main() {
short unsigned int n, **a, i, j;
printf("n: "); scanf("%hu", &n);
a = malloc(sizeof(short unsigned int) * n);
for (i=0; i < n; i++) {
a[i] = malloc(sizeof(short unsigned int) * n);
for (j=0; j < n; j++) a[i][j] = 0;
}
for (i=0; i < n; i++) {
for (j=0; j < n; j++) {
printf("%hu ", a[i][j]);
}
puts("");
}
return 0;
}
But it doesn't make it, output:

n: 5
41136 466 0 0 0
0 0 0 0 0
0 0 0 0 0
0 0 0 0 0
0 0 0 0 0
What is wrong? I can't figure it out for the life of me.

[jespdj]

a is a pointer to pointers. This line is wrong:

a = malloc(sizeof(short unsigned int) * n);
It should have been:

a = malloc(sizeof(short unsigned int *) * n);

[Znupi]

Oh wow, you are right, never thought of that. Thanks a bunch :)

[ad_267]

Usually if you want a 2D array you simply use a 1D array that is n*n long.

So to access A(i,j) you use A(i*n + j).

Don't know if that's actually helpful or not but thought I'd point it out.