TicTacToe

#include <stdio.h>
#include <stdlib.h>
#include <conio.h>

char box[10] = {'o','1','2','3','4','5','6','7','8','9'};
int win[3]={0,0,0};
int round=1;
int checkwin();
void grid();

int main()
{

while(round<=3){
    int player = 1, i, choice;
    char mark;
    do
    {

        grid();
        player = (player % 2) ? 1 : 2;

        printf("\tPlayer %d, enter a number:  ", player);
        scanf("%d", &choice);

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

        if (choice == 1 && box[1] == '1')
            box[1] = mark;

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

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

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

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

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

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

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

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

        else
        {
            printf("\tInvalid move ");
            player--;
            getch();
        }
       i = checkwin();
       player++;
    }while (i ==  - 1);

    grid();

    if (i == 1)
    {
       printf("\tPlayer %d won the round. \n",--player);
       win[player]++;
       box[1]='1',box[2]='2',box[3]='3',box[4]='4',box[5]='5',box[6]='6',box[7]='7',box[8]='8',box[9]='9';
    }

    else
        {
        win[1]++;
        win[2]++;
        printf("\tDraw");
        box[1]='1',box[2]='2',box[3]='3',box[4]='4',box[5]='5',box[6]='6',box[7]='7',box[8]='8',box[9]='9';
           }
    round++;
    getch();
}
printf("\n\tPlayer 1: %d pts \n\tPlayer 2: %d pts \n",win[1],win[2]);

if(win[1]>win[2]){printf("\n\tPlayer 1 Wins.");}
else if (win[1]<win[2]){printf("\nPlayer 2 Wins.");}
else {printf("\nIt's A Draw");}
return 0;
}

int checkwin()
{
    if (box[1] == box[2] && box[2] == box[3])
        return 1;

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

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

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

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

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

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

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

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

        return 0;
    else
        return  - 1;
}

void grid()
{
    system("cls");
    printf("\n\n\t\tTic Tac Toe\n\n");
    printf("\tPlayer 1 (X)  -  Player 2 (O)\n\n\n");
    printf("\t       Round: %d\n\n",round);
    printf("\t       |     |     \n");
    printf("\t    %c  |  %c  |  %c \n", box[1], box[2], box[3]);
    printf("\t  _____|_____|_____\n");
    printf("\t       |     |     \n");
    printf("\t    %c  |  %c  |  %c \n", box[4], box[5], box[6]);
    printf("\t  _____|_____|_____\n");
    printf("\t       |     |     \n");
    printf("\t    %c  |  %c  |  %c \n", box[7], box[8], box[9]);
    printf("\t       |     |     \n\n");
}