C++: Tic Tac Toe Computer Random Moves

Question

I need help with my tic tac toe, because I am stuck at this one. The random moves that the computer makes will overwrite the old ones, and I am not sure how to fix this.

if (computer == 1)  //computer = 1, means it's computer's turn
{
    i = rand() % 3;
    j = rand() % 3;
    if(board[i][j] !='X' && board[i][j] != '0')
    {
        board[i][j] = '0';
        computer--;  // computer = 0, means it's the player's turn
    }   
}

My 2D array is this one:

char board[3][3] = 
{{'1', '2', '3'}, 
{'4', '5', '6'}, 
{'7', '8', '9'}};

Answer 1

This works:

    if (computer == 1)  //computer = 1, means it's computer's turn
        {
            bool found = false;
            while (found == false)
            {
            i = rand() % 3;
            j = rand() % 3;
            if(board[i][j] !='X' && board[i][j] != '0')
            {

            board[i][j] = '0';
            found = true;
            computer--;  // computer = 0, means it's the player's turn
            }

            }