1. (20 points) Complete the Connect 4 program you began in Lab 4. The program should read in integers, alternately placing R and B in the lowest position of the indicated column until either one team gets 4 of their character in a row or the entire board is filled. You do not need to check if a move is valid; assume that all the entered values are in the range 07 and there is always at least one empty spot in the selected column. At the end of the game, your program should print one of the following messages: Red wins! Black wins! Its a tie!

LAB 4

create a board variable that is a 2D array (8 8) of characters by putting the following in the file: char board[8][8]; Next create a main function for the program to run. Recall that the simplest main is the following: int main() { } Once youve typed this in and saved the file (Control-x Control-s), you can suspend emacs with Control-z to get back to a prompt. Then type the following to compile and run this program: gcc -Wall -std=gnu99 -o connect4 connect4.c ./connect4 Once you run that (and see it does nothing...), reopen the suspended version of emacs using the command fg. Inside the main function, add a nested loop to set every cell of the 2D array to contain a period: for(int i=0; i < 8; i++) for(int j=0; j < 8; j++) board[i][j] = .; (Unlike in Java, C does not automatically initialize your variables for you.) Then write a second nested loop to print the contents of this variable row by row. Make board[0][0] the bottom left coordinate, board[7][0] the bottom right coordinate, etc; the first array index is the x coordinate and both coordinates count from the bottom left. You can check your code by temporarily setting the corners to distinctive values before printing the board:

board[0][0] = A; board[0][7] = B; board[7][0] = C; board[7][7] = D; I suggest that you put the printing code into a function. Once you have the board printing, write code so that the red player can make a move. This means they enter an integer in the range 07 and the lowest period in that column is replaced with an R character. To read a value into the integer variable x, use the following: scanf("%d", &x); Next, modify your program so that after the red player moves, the blue player gets a turn (putting a B into the lowest period in some column), followed by the red player again, with the players alternating until the entire board is full. Again, it is helpful if the code for making a move is a function that takes the player (either R or B) as an argument. Once you can make moves, it is time to start detecting winning moves. A player wins if they ever get 4 of their pieces into consecutive positions, i.e. 4 pieces next to each other in a row, column, or diagonal line. If this happens, print a message about that player winning and exit the program. (You can use the function exit to exit the program. You should pass it the argument 0 and will need to add #include to the top of the file.) If you get all of that working, spend the rest of the period refining the program. (At the end of the period, be sure to save your program again and exit emacs with Control-x Control-c.) Can you detect illegal moves (out of range values or trying to put another piece into a column that is already full)? If a player tries one of these things, refuse the move and ask for another. What about allowing rematches and keeping a running score of games won? Suggesting winning moves or moves that block the other player from winning moves?