Getting memory Address like values of my array when printing (C programming)

Question

I am trying to create 8x8 array, but when I am printing that array, after [7][7] Element I am not getting the exact values that I assigned while creating the array. My array is a follows

#include <stdio.h>
int main() {
    int puzzle[8][8] = {
    //   0 1 2 3 4 5 6 7 8 
        {0,0,2,0,4,0,5,9,3},//0
        {7,0,0,3,1,0,4,0,8},//1
        {4,0,0,8,0,5,1,0,2},//2
        {8,3,0,2,0,0,0,0,0},//3
        {0,9,6,0,0,0,3,5,0},//4
        {0,0,0,0,0,4,0,8,6},//5
        {3,0,1,5,0,9,0,0,7},//6
        {6,0,5,0,2,8,0,0,1},//7
        {0,4,0,0,7,0,6,0,0} //8
    }; 
for (int i = 0; i < 9; ++i)
  {
    for (int j = 0; j < 9; ++j)
    {
      printf("\n puzzle[%d][%d] = %d",i,j,puzzle[i][j]);
    }
  }


    return 0;
}

and I am getting output as

 puzzle[0][0] = 0
     puzzle[0][1] = 0
     puzzle[0][2] = 2
     puzzle[0][3] = 0
     puzzle[0][4] = 4
     puzzle[0][5] = 0
     puzzle[0][6] = 5
     puzzle[0][7] = 9
     puzzle[0][8] = 7
     puzzle[1][0] = 7
     puzzle[1][1] = 0
     puzzle[1][2] = 0
     puzzle[1][3] = 3
     puzzle[1][4] = 1
     puzzle[1][5] = 0
     puzzle[1][6] = 4
     puzzle[1][7] = 0
     puzzle[1][8] = 4
     puzzle[2][0] = 4
    puzzle[2][1] = 0
     puzzle[2][2] = 0
     puzzle[2][3] = 8
     puzzle[2][4] = 0
     puzzle[2][5] = 5
     puzzle[2][6] = 1
     puzzle[2][7] = 0
     puzzle[2][8] = 8
     puzzle[3][0] = 8
     puzzle[3][1] = 3
     puzzle[3][2] = 0
     puzzle[3][3] = 2
     puzzle[3][4] = 0
     puzzle[3][5] = 0
     puzzle[3][6] = 0
     puzzle[3][7] = 0
     puzzle[3][8] = 0
     puzzle[4][0] = 0
     puzzle[4][1] = 9
     puzzle[4][2] = 6
     puzzle[4][3] = 0
     puzzle[4][4] = 0
     puzzle[4][5] = 0
     puzzle[4][6] = 3
     puzzle[4][7] = 5
     puzzle[4][8] = 0
     puzzle[5][0] = 0
     puzzle[5][1] = 0
     puzzle[5][2] = 0
     puzzle[5][3] = 0
     puzzle[5][4] = 0
     puzzle[5][5] = 4
     puzzle[5][6] = 0
     puzzle[5][7] = 8
     puzzle[5][8] = 3
     puzzle[6][0] = 3
     puzzle[6][1] = 0
     puzzle[6][2] = 1
     puzzle[6][3] = 5
     puzzle[6][4] = 0
     puzzle[6][5] = 9
     puzzle[6][6] = 0
     puzzle[6][7] = 0
     puzzle[6][8] = 6
     puzzle[7][0] = 6
     puzzle[7][1] = 0
     puzzle[7][2] = 5
     puzzle[7][3] = 0
     puzzle[7][4] = 2
     puzzle[7][5] = 8
     puzzle[7][6] = 0
     puzzle[7][7] = 0
     puzzle[7][8] = -445142480
     puzzle[8][0] = -445142480
     puzzle[8][1] = 32765
     puzzle[8][2] = 480800256
     puzzle[8][3] = -129200335
     puzzle[8][4] = 0
     puzzle[8][5] = 0
     puzzle[8][6] = -2108403533
     puzzle[8][7] = 32522
     puzzle[8][8] = -2106304992

As you can see I am not getting exact values that I assigned to [7][8]th position. The output I am getting looks like address or ids. I am not getting why it is happening, is it ide problem or is there any mistake in my code?

Answer 1

As you already seem to understand, array elements are indexed beginning at position zero. So when you define an array of size n arr[n], you can only hold n elements(0 to n - 1) in this array. Same applies for multi-dimensional arrays.

In your case you have only defined an array of size 8x8 which can hold only 64 elements. But you are trying to assign 9x9 81 elements to your array. Thus, only indices puzzle[0][0] to puzzle[7][7] are accessible.

Answer 2

The compiler shall issue a message for this initialization

int puzzle[8][8] = {
//   0 1 2 3 4 5 6 7 8 
    {0,0,2,0,4,0,5,9,3},//0
    {7,0,0,3,1,0,4,0,8},//1
    {4,0,0,8,0,5,1,0,2},//2
    {8,3,0,2,0,0,0,0,0},//3
    {0,9,6,0,0,0,3,5,0},//4
    {0,0,0,0,0,4,0,8,6},//5
    {3,0,1,5,0,9,0,0,7},//6
    {6,0,5,0,2,8,0,0,1},//7
    {0,4,0,0,7,0,6,0,0} //8
};

because elements of the array are arrays with 8 elements bur you are supplying 9 initializers for each element.

And if an array has N elements then the valid range of indices is [0, N).