Thread: Is there a bug in this part of my algorithm for connect 4?

Hi,

The following is a part of my algorithm for making a winning move in a game of connect four. However, it doen't really work. It can check make win moves if the line is a diagonal one, but not vertical or horizontal ones. I'd already spent some hours on it, but still can't figure out where it went wrong. I've already written a driver program to test the function for those who are willing to help me.

Thnx in advance

Code:

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

char board[ 7 ][ 6 ] = { {' ', ' ', ' ', 'X', 'X', 'X'   },
                         {' ', ' ', ' ', ' ', ' ', ' '   },
                         {' ', ' ', ' ', ' ', ' ', ' '   },
                         {' ', ' ', ' ', ' ', ' ', ' '   },
                         {' ', ' ', ' ', ' ', ' ', ' '   },
                         {' ', ' ', ' ', ' ', ' ', ' '   },
                         {' ', ' ', ' ', ' ', ' ', ' '   } };

int makeWinMove( char currentPlayer, int mode )
{
   int row;
   int col;

   /* check vertically */
   for ( col = 0; col < 7; col++ )
      for ( row = 5; row < 2; row-- ) {

         if ( board[ col ][ row ] == currentPlayer &&
              board[ col ][ row - 1 ] == currentPlayer &&
              board[ col ][ row - 2 ] == currentPlayer &&
              board[ col ][ row - 3 ] != 'X' &&
              board[ col ][ row - 3 ] != 'O' ) {

              return 1; /* indicating success */
         }

      }

   /* check horizontally */
   for ( row = 0; row < 6; row++ )
      for ( col = 0; col < 4; col++ ) {
         if ( board[ col ][ row ] == currentPlayer &&
              board[ col + 1 ][ row ] == currentPlayer &&
              board[ col + 2 ][ row ] == currentPlayer &&
              board[ col + 3 ][ row ] != 'X' &&
              board[ col + 3 ][ row ] != 'O' &&
              ( board[ col + 3 ][ row + 1 ] != ' ' || row == 6 )) {

              return 1;
         }
         if ( board[ col ][ row ] == currentPlayer &&
              board[ col + 1 ][ row ] == currentPlayer &&
              board[ col + 3 ][ row ] == currentPlayer &&
              board[ col + 2 ][ row ] != 'X' &&
              board[ col + 2 ][ row ] != 'O' &&
              ( board[ col + 2 ][ row + 1 ] != ' ' || row == 6 )) {

              return 1;
         }
         if ( board[ col ][ row ] == currentPlayer &&
              board[ col + 3 ][ row ] == currentPlayer &&
              board[ col + 2 ][ row ] == currentPlayer &&
              board[ col + 1 ][ row ] != 'X' &&
              board[ col + 1 ][ row ] != 'O' &&
              ( board[ col + 1 ][ row + 1 ] != ' ' || row == 6 )) {

              return 1;
         }
         if ( board[ col + 3 ][ row ] == currentPlayer &&
              board[ col + 1 ][ row ] == currentPlayer &&
              board[ col + 2 ][ row ] == currentPlayer &&
              board[ col ][ row ] != 'X' &&
              board[ col ][ row ] != 'O' &&
              ( board[ col ][ row + 1 ] != ' ' || row == 6 )) {

              return 1;
         }
      }

   /* check diagonally (NE) */
   for ( row = 5; row > 2; row-- )
      for ( col = 0; col < 4; col++ ) {
         if ( board[ col ][ row ] == currentPlayer &&
              board[ col + 1 ][ row - 1 ] == currentPlayer &&
              board[ col + 2 ][ row - 2 ] == currentPlayer &&
              board[ col + 3 ][ row - 3 ] != 'X' &&
              board[ col + 3 ][ row - 3 ] != 'O' &&
              ( board[ col + 3 ][ row - 3 + 1 ] != ' ' || row == 5 )) {

              return 1;
         }
         if ( board[ col ][ row ] == currentPlayer &&
              board[ col + 1 ][ row - 1 ] == currentPlayer &&
              board[ col + 3 ][ row - 3 ] == currentPlayer &&
              board[ col + 2 ][ row - 2 ] != 'X' &&
              board[ col + 2 ][ row - 2 ] != 'O' &&
              ( board[ col + 2 ][ row - 2 + 1 ] != ' ' || row == 5 )) {

              return 1;
         }
         if ( board[ col ][ row ] == currentPlayer &&
              board[ col + 3 ][ row - 3 ] == currentPlayer &&
              board[ col + 2 ][ row - 2 ] == currentPlayer &&
              board[ col + 1 ][ row - 1 ] != 'X' &&
              board[ col + 1 ][ row - 1 ] != 'O' &&
              ( board[ col + 1 ][ row - 1 + 1 ] != ' ' || row == 5 )) {

              return 1;
         }
         if ( board[ col + 3 ][ row - 3 ] == currentPlayer &&
              board[ col + 1 ][ row - 1 ] == currentPlayer &&
              board[ col + 2 ][ row - 2 ] == currentPlayer &&
              board[ col ][ row ] != 'X' &&
              board[ col ][ row ] != 'O' &&
              ( board[ col ][ row + 1 ] != ' ' || row == 5 )) {

              return 1;
         }

      }

   /* check diagonally (NW) */
   for ( row = 5; row > 2; row-- )
      for ( col = 6; col < 2; col-- ) {
         if ( board[ col ][ row ] == currentPlayer &&
              board[ col - 1 ][ row - 1 ] == currentPlayer &&
              board[ col - 2 ][ row - 2 ] == currentPlayer &&
              board[ col - 3 ][ row - 3 ] != 'X' &&
              board[ col - 3 ][ row - 3 ] != 'O' &&
              ( board[ col - 3 ][ row - 3 + 1 ] != ' ' || row == 5 )) {

              return 1;
         }
         if ( board[ col ][ row ] == currentPlayer &&
              board[ col - 1 ][ row - 1 ] == currentPlayer &&
              board[ col - 3 ][ row - 3 ] == currentPlayer &&
              board[ col - 2 ][ row - 2 ] != 'X' &&
              board[ col - 2 ][ row - 2 ] != 'O' &&
              ( board[ col - 2 ][ row - 2 + 1 ] != ' ' || row == 5 )) {

              return 1;
         }
         if ( board[ col ][ row ] == currentPlayer &&
              board[ col - 3 ][ row - 3 ] == currentPlayer &&
              board[ col - 2 ][ row - 2 ] == currentPlayer &&
              board[ col - 1 ][ row - 1 ] != 'X' &&
              board[ col - 1 ][ row - 1 ] != 'O' &&
              ( board[ col - 1 ][ row - 1 + 1 ] != ' ' || row == 5 )) {

              return 1;
         }
         if ( board[ col - 3 ][ row - 3 ] == currentPlayer &&
              board[ col - 1 ][ row - 1 ] == currentPlayer &&
              board[ col - 2 ][ row - 2 ] == currentPlayer &&
              board[ col ][ row ] != 'X' &&
              board[ col ][ row ] != 'O' &&
              ( board[ col ][ row + 1 ] != ' ' || row == 5 )) {

              return 1;
         }
      }

   return 0;
}

int main()
{
   int result;

   if ( ( result = makeWinMove( 'X', 0 ) ) == 1 )
      printf( "Made a win move...\n" );

   system("PAUSE");
   return 0;
}