Why does this program print 0 instead of the specific set of values from a specified array?

Question

I'd like to know why the printf function in this tiny program returns 0 instead of the array of numbers 3 2 2:

int main(){
    int mat[2][2][2] = {{3,1,1},{2,2,2}};

    printf("first x, 2nd y, 2nd z = %d\n",mat[0][1][1]);
}

While working with X by Y matrices in C retrieving any value XxY was a breeze, but once I added another dimension I ran into this problem. I think I must've a misunderstanding of the way C deals with coordinates in arrays. Thanks a lot!

Answer 1

In

int mat[2][2][2] = {{3,1,1},{2,2,2}};

you declare a 3D array but you give initialization for a 2D, the values are not placed where you expect

#include <stdio.h>

int main(){
  int mat[2][2][2] = {{3,1,1},{2,2,2}};

  for (int i = 0; i != 2; ++i)
    for (int j = 0; j != 2; ++j)
      for (int k = 0; k != 2; ++k)
        printf("%d %d %d -> %d\n", i, j, k, mat[i][j][k]);
  return 0;
}

Execution : pi@raspberrypi:/tmp $ ./a.out

0 0 0 -> 3
0 0 1 -> 1
0 1 0 -> 1
0 1 1 -> 0
1 0 0 -> 2
1 0 1 -> 2
1 1 0 -> 2
1 1 1 -> 0
pi@raspberrypi:/tmp $ 

Furthermore because your array has 8 int but the init value has only 6 the compiler initializes the two not specified entries with 0