Wrong results when assigning to int array in c++

#include <iostream>
using std::cout;
using std::cin;
using std::endl;

int main(){
    int v[5];
    int a[5][5];
    int i = 0, j = 0;

    for (i = 0; i < 5; i++){
        v[i] = 0;
        for (j = 0; j < 5; j++){
            a[i][j] = 0;
            cout << "A[" << i << ", " << j << "] = " << endl;
            cin >> a[i][j];
            v[i] = v[i] + a[i][j];
        }   
        v[i] = v[i] / 5;
    }   

    for (i = 0; i < 30; i++){
        cout << "v[" << i << "] = " << v[i] << endl;
    }
}

When I remove the v[i] = 0 line just under the first loop the code runs but returns very large numbers. I don’t understand how this is happening. Grateful for any help.

>Solution :

Initializing a value in c++ like int v[5]; just reserves space. It does nothing to initialize the values to 0 or something. Anything could be in those five indices. Whatever happens to be in that address space.