If you consider the game board in Connect Four carefully, you can see that it is a two dimensional grid of squares. When a player deposits a disc in a column, the disc must “fall” until it is either just above the bottom (i.e. in the last row) or it is sitting upon another disc. There are many models that we could use for this, but for this assignment, we will use a simple two-dimensional array.

There are a number of changes that we need to make to complete our game:

• We need to allocate the space for the game board. While this is a fixed size board, we will still dynamically allocate the space for the board in the initialization function.
• Whenever we allocate memory, we need to make sure that we free it as well. Free the memory in the teardown function.
• Print the game board in the display the world function. Use one character for an empty spot, one character for the discs for player one and another character for the discs for player two. You may use whatever characters you prefer. You may make the display as complex as you wish so long as we can clearly see what moves are available.
• The remainder of the work to be done goes into “update the state of the world.”
  • We must look through the column of the array and add the new disc into the array in the appropriate location based on the column that the player chose.
  • We must signal to end the game if the column that the player chose is full.
  • We must look for 4 discs belonging to one player in a straight line. The line can be horizontal, vertical, or diagonal. When we find this, we must signal end of the game.
  • With these changes, we can now play the game with players taking turns at the keyboard.