Display symbol on grid when key pressed

#include <iostream>
#include <conio.h>

using std::cout;
using std::cin;
using std::endl;


void main()
{
    setlocale(LC_ALL, "Russian");

    char sensor = 0;
    char grid[3][3] = { '*', '*', '*',
                        '*', '*', '*',
                        '*', '*', '*'};


    while (sensor != 27)
    {

        for (int i = 0; i < 3; i++)
        {
            cout << "\t\t\t\t";
            for (int j = 0; j < 3; j++)
            {
                cout << grid[i][j] << " ";
            }
            cout << endl;
        }


        for (int i = 0; i < 3; i++)
        {
            for (int j = 0; j < 3; j++)
            {
                grid[i][j] = '*';
            }
            cout << endl;
        }

        sensor = getch();

        system("cls");

        switch (sensor)
        {
        case 119:
            grid[0][1] = '|';
            break;
        case 87:
            grid[0][1] = '|';
            break;
        case 97:
            grid[1][0] = '_';
            break;
        case 65:
            grid[1][0] = '_';
            break;
        case 115:
            grid[2][1] = '|';
            break;
        case 83:
            grid[2][1] = '|';
            break;
        case 100:
            grid[1][2] = '_';
            break;
        case 68:
            grid[1][2] = '_';
            break;
        case 32:
            grid[2][0] = '_';
            grid[2][1] = '_';
            grid[2][2] = '_';
            break;
        }

    }
}