Tic-tac- toe game sourcecode in C

INTRODUCTION

Tic-tac-toe is a simple two player game. It is a pen and paper game.It is mostly played especially in childhood between two player. each player tries to complete the boxes horizontally,vertically or diagonally. The player to finished first is declared the winner.

This is a simple  game without the AI(artificial intelligence). This code doesnot contain the AI i.e player cannot play against the computer player.


HERE IS THE COMPLETE CODE:

/* This is the complete source code of tic tac toe in C language. It is perfectly run in the codeblocks IDE */

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



int board[10] = {2,2,2,2,2,2,2,2,2,2};
int turn = 1,flag = 0;
int player,comp;

void menu();
void go(int n);
void start_game();
void check_draw();
void draw_board();
void player_first();
void put_X_O(char ch,int pos);
 COORD coord={0,0}; // this is global variable
                                    //center of axis is set to the top left cornor of the screen
void gotoxy(int x,int y)
{
    coord.X=x;
    coord.Y=y;
    SetConsoleCursorPosition(GetStdHandle(STD_OUTPUT_HANDLE),coord);
}



 void main()
{
 system("cls");
 menu();
 getch();

}

void menu()
{
 int choice;
 system("cls");
 printf("\n--------MENU--------");
 printf("\n1 : Play with X");
 printf("\n2 : Play with O");
 printf("\n3 : Exit");
 printf("\nEnter your choice:>");
 scanf("%d",&choice);
 turn = 1;
 switch (choice)
 {
  case 1:
   player = 1;
   comp = 0;
   player_first();
   break;
  case 2:
   player = 0;
   comp = 1;
   start_game();
   break;
  case 3:
   exit(1);
  default:
   menu();
 }
}

int make2()
{
 if(board[5] == 2)
  return 5;
 if(board[2] == 2)
  return 2;
 if(board[4] == 2)
  return 4;
 if(board[6] == 2)
  return 6;
 if(board[8] == 2)
  return 8;
 return 0;
}

int make4()
{
 if(board[1] == 2)
  return 1;
 if(board[3] == 2)
  return 3;
 if(board[7] == 2)
  return 7;
 if(board[9] == 2)
  return 9;
 return 0;
}

int posswin(int p)
{
// p==1 then X   p==0  then  O
 int i;
 int check_val,pos;

 if(p == 1)
  check_val = 18;
 else
  check_val = 50;

 i = 1;
 while(i<=9)//row check
 {
  if(board[i] * board[i+1] * board[i+2] == check_val)
  {
   if(board[i] == 2)
    return i;
   if(board[i+1] == 2)
    return i+1;
   if(board[i+2] == 2)
    return i+2;
  }
  i+=3;
 }

 i = 1;
 while(i<=3)//column check
 {
  if(board[i] * board[i+3] * board[i+6] == check_val)
  {
   if(board[i] == 2)
    return i;
   if(board[i+3] == 2)
    return i+3;
   if(board[i+6] == 2)
    return i+6;
  }
  i++;
 }

 if(board[1] * board[5] * board[9] == check_val)
 {
  if(board[1] == 2)
   return 1;
  if(board[5] == 2)
   return 5;
  if(board[9] == 2)
   return 9;
 }

 if(board[3] * board[5] * board[7] == check_val)
 {
  if(board[3] == 2)
   return 3;
  if(board[5] == 2)
   return 5;
  if(board[7] == 2)
   return 7;
 }
 return 0;
}

void go(int n)
{
 if(turn % 2)
  board[n] = 3;
 else
  board[n] = 5;
 turn++;
}

void player_first()
{
 int pos;

 check_draw();
 draw_board();
 gotoxy(30,18);
 printf("Your Turn :> ");
 scanf("%d",&pos);

 if(board[pos] != 2)
  player_first();

 if(pos == posswin(player))
 {
  go(pos);
  draw_board();
  gotoxy(30,20);
  //textcolor(128+RED);
  printf("Player Wins");
  getch();
  exit(0);
 }

 go(pos);
 draw_board();
 start_game();
}

void start_game()
{
 // p==1 then X   p==0  then  O
 if(posswin(comp))
 {
  go(posswin(comp));
  flag = 1;
 }
 else
 if(posswin(player))
  go(posswin(player));
 else
 if(make2())
  go(make2());
 else
  go(make4());
 draw_board();

 if(flag)
 {
  gotoxy(30,20);
  //textcolor(128+RED);
  printf("Computer wins");
  getch();
 }
 else
  player_first();
}

void check_draw()
{
 if(turn > 9)
 {
  gotoxy(30,20);
  //textcolor(128+RED);
  printf("Game Draw");
  getch();
  exit(0);
 }
}

void draw_board()
{
 int j;

 for(j=9;j<17;j++)
 {
  gotoxy(35,j);
  printf("|       |");
 }
 gotoxy(28,11);
 printf("-----------------------");
 gotoxy(28,14);
 printf("-----------------------");

 for(j=1;j<10;j++)
 {
  if(board[j] == 3)
   put_X_O('X',j);
  else
  if(board[j] == 5)
   put_X_O('O',j);
 }
}

void put_X_O(char ch,int pos)
{
 int m;
 int x = 31, y = 10;

 m = pos;

 if(m > 3)
 {
  while(m > 3)
  {
   y += 3;
   m -= 3;
  }
 }
 if(pos % 3 == 0)
  x += 16;
 else
 {
  pos %= 3;
  pos--;
  while(pos)
  {
   x+=8;
   pos--;
  }
 }
 gotoxy(x,y);
 printf("%c",ch);
}

OUTPUT: