Characters duplicate in a multidimensional array

Question

I have created an empty char multidimensional array, but when I try to change a specific value, it sometimes duplicates to another space in the array.

Example:

#include <iostream>
using namespace std;

char arr[2][2] = { 0 };

int main ()
{
    arr[2][0] = 'A';
    for(int i = 0; i < 3; ++i)
    {
        for(int j = 0; j < 3; ++j)
        {
            cout << "arr[" << i << "][" << j << "] = " << arr[i][j] << endl;
        }
    }
}

Output:

arr[0][0] =
arr[0][1] =
arr[0][2] =
arr[1][0] =
arr[1][1] =
arr[1][2] = A
arr[2][0] = A
arr[2][1] =
arr[2][2] =

The character A should only appear in [2][0] but it also appears in [1][2]. This happens only in these spaces:

[1][0], [2][0], [0][2], [2][2]

I was able to recreate this with a bigger array, but I can't say the specific values.

I have tried defining inside the main() function but it created another problem, random characters started appearing in random locations of the array.

I tried initializing the array with char arr[2][2] = { 0 }, but it didn't help.

Answer 1

When you declare char arr[2][2] = { 0 };, that's a 2x2 array. Which means it's indices go from 0 to 1. You're writing into index 2, which is outside of array bounds.