Tic_Tac_Toe _ AI

I saw two versions of Tic Tac Toe game program submitted in two consecutive days, both of them did not have the AI ability (playing against the computer option) .. so.. I thought why not submit this code i wrote one year ago, it is nothing fancy. The code allows one player to play against the computer, the user goes first always, the program declare the winner or in case of draw .. a draw. I did not include two players option, but if any one is interested i can add it..