Old Tic

#include <iostream>
#include <conio.h>
using namespace std;

class Board {
protected:
    char square[10] = { 'o','1','2','3','4','5','6','7','8','9' };

public:
    void board()
    {
        system("cls");
        cout << "\n\n\tTic Tac Toe\n\n";

        cout << "Player 1 (X)  -  Player 2 (O)" << endl << endl;
        cout << endl;

        cout << "     |     |     " << endl;
        cout << "  " << square[1] << "  |  " << square[2] << "  |  " << square[3] << endl;

        cout << "_____|_____|_____" << endl;
        cout << "     |     |     " << endl;

        cout << "  " << square[4] << "  |  " << square[5] << "  |  " << square[6] << endl;

        cout << "_____|_____|_____" << endl;
        cout << "     |     |     " << endl;

        cout << "  " << square[7] << "  |  " << square[8] << "  |  " << square[9] << endl;

        cout << "     |     |     " << endl << endl;
    }
};

class Player : protected Board {
protected:


public:
    int choice()
    {
        int player = 1, i, choice;

        char mark;
        do
        {
            board();
            player = (player % 2) ? 1 : 2;

            cout << "Player " << player << ", enter a number:  ";
            cin >> choice;

            mark = (player == 1) ? 'X' : 'O';

            if (choice == 1 && square[1] == '1')

                square[1] = mark;
            else if (choice == 2 && square[2] == '2')

                square[2] = mark;
            else if (choice == 3 && square[3] == '3')

                square[3] = mark;
            else if (choice == 4 && square[4] == '4')

                square[4] = mark;
            else if (choice == 5 && square[5] == '5')

                square[5] = mark;
            else if (choice == 6 && square[6] == '6')

                square[6] = mark;
            else if (choice == 7 && square[7] == '7')

                square[7] = mark;
            else if (choice == 8 && square[8] == '8')

                square[8] = mark;
            else if (choice == 9 && square[9] == '9')

                square[9] = mark;
            else
            {
                cout << "Invalid move ";

                player--;
                cin.ignore();
                cin.get();
            }
            i = checkwin();

            player++;
        } while (i == -1);
        board();
        if (i == 1)

            cout << "==>\aPlayer " << --player << " win ";
        else
            cout << "==>\aGame draw";

        cin.ignore();
        cin.get();
        return 0;
    }

    int checkwin()
    {
        if (square[1] == square[2] && square[2] == square[3])

            return 1;
        else if (square[4] == square[5] && square[5] == square[6])

            return 1;
        else if (square[7] == square[8] && square[8] == square[9])

            return 1;
        else if (square[1] == square[4] && square[4] == square[7])

            return 1;
        else if (square[2] == square[5] && square[5] == square[8])

            return 1;
        else if (square[3] == square[6] && square[6] == square[9])

            return 1;
        else if (square[1] == square[5] && square[5] == square[9])

            return 1;
        else if (square[3] == square[5] && square[5] == square[7])

            return 1;
        else if (square[1] != '1' && square[2] != '2' && square[3] != '3'
            && square[4] != '4' && square[5] != '5' && square[6] != '6'
            && square[7] != '7' && square[8] != '8' && square[9] != '9')

            return 0;
        else
            return -1;
    }

};

class Operation : protected Player {
protected:


public:
    void start()
    {
        choice();
    }
};

int main() {
    Operation Op;
    Op.start();

    _getch();
}