Question

The following is a C program that is a video game version of Connect 4. The code works fine as is now but I want to change the way you input which column you drop a disk into. Currently, you type in 1 and it goes into column 1. If you type in 6, it goes into column 6 and so on. But I want to make it so you input A or a, then it goes into column 1 and if you input G or g then it goes into column 7. (A-G instead of 1-7 for the columns) Additionally I want to make it so if you press Q or q the game quits and exits. I want to implement this in the whoseTurnIsNext function. Help would be appreciated.

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#define BOARD_ROWS 6
#define BOARD_COLS 7

void displayWorld(char *board);
int whoseTurnIsNext(char *board, int player, const char*);
int checkWin(char *board);
int checkFour(char *board, int, int, int, int);
int horizontalCheck(char *board);
int verticalCheck(char *board);
int diagonalCheck(char *board);

int main(int argc, char *argv[]){
const char *PIECES = "XO";
char board[BOARD_ROWS * BOARD_COLS];
memset(board, ' ', BOARD_ROWS * BOARD_COLS);

int turn, done = 0;

for(turn = 0; turn < BOARD_ROWS * BOARD_COLS && !done; turn++){
displayWorld(board);
while(!whoseTurnIsNext(board, turn % 2, PIECES)){
displayWorld(board);
puts("**Column full!**\n");
}
done = checkWin(board);
}
displayWorld(board);

if(turn == BOARD_ROWS * BOARD_COLS && !done){
puts("It's a tie!");
} else {
turn--;
printf("Player %d (%c) wins!\n", turn % 2 + 1, PIECES[turn % 2]);
}

return 0;

}
void displayWorld(char *board){
int row, col;

//system("clear");
puts("\n ****Connect Four****\n");
for(row = 0; row < BOARD_ROWS; row++){
for(col = 0; col < BOARD_COLS; col++){
printf("| %c ", board[BOARD_COLS * row + col]);
}
puts("|");
puts("-----------------------------");

}
puts(" 1 2 3 4 5 6 7\n");

}
int whoseTurnIsNext(char *board, int player, const char *PIECES){
int row, col = 0;
printf("Player %d (%c):\nEnter number coordinate: ", player + 1, PIECES[player]);

while(1){
if(1 != scanf("%d", &col) || col < 1 || col > 7 ){
while(getchar() != '\n');
puts("Number out of bounds! Try again.");
} else {
break;
}
}
col--;

for(row = BOARD_ROWS - 1; row >= 0; row--){
if(board[BOARD_COLS * row + col] == ' '){
board[BOARD_COLS * row + col] = PIECES[player];
return 1;
}
}
return 0;

}
int checkWin(char *board){
return (horizontalCheck(board) || verticalCheck(board) || diagonalCheck(board));

}
int checkFour(char *board, int a, int b, int c, int d){
return (board[a] == board[b] && board[b] == board[c] && board[c] == board[d] && board[a] != ' ');

}
int horizontalCheck(char *board){
int row, col, idx;
const int WIDTH = 1;

for(row = 0; row < BOARD_ROWS; row++){
for(col = 0; col < BOARD_COLS - 3; col++){
idx = BOARD_COLS * row + col;
if(checkFour(board, idx, idx + WIDTH, idx + WIDTH * 2, idx + WIDTH * 3)){
return 1;
}
}
}
return 0;

}
int verticalCheck(char *board){
int row, col, idx;
const int HEIGHT = 7;

for(row = 0; row < BOARD_ROWS - 3; row++){
for(col = 0; col < BOARD_COLS; col++){
idx = BOARD_COLS * row + col;
if(checkFour(board, idx, idx + HEIGHT, idx + HEIGHT * 2, idx + HEIGHT * 3)){
return 1;
}
}
}
return 0;

}
int diagonalCheck(char *board){
int row, col, idx, count = 0;
const int DIAG_RGT = 6, DIAG_LFT = 8;

for(row = 0; row < BOARD_ROWS - 3; row++){
for(col = 0; col < BOARD_COLS; col++){
idx = BOARD_COLS * row + col;
if(count <= 3 && checkFour(board, idx, idx + DIAG_LFT, idx + DIAG_LFT * 2, idx + DIAG_LFT * 3) || count >= 3 && checkFour(board, idx, idx + DIAG_RGT, idx + DIAG_RGT * 2, idx + DIAG_RGT * 3)){
return 1;
}
count++;
}
count = 0;
}
return 0;

}

Answer 1

I have made changes in the code from line 27 to 36 (main function) and from line 74 to 114 (whoseTurnIsNext function). And also added #include <ctype.h>

C code screenshot:

C code:

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <ctype.h>
#define BOARD_ROWS 6
#define BOARD_COLS 7

void displayWorld(char *board);
int whoseTurnIsNext(char *board, int player, const char *);
int checkWin(char *board);
int checkFour(char *board, int, int, int, int);
int horizontalCheck(char *board);
int verticalCheck(char *board);
int diagonalCheck(char *board);

int main(int argc, char *argv[])
{
    const char *PIECES = "XO";
    char board[BOARD_ROWS * BOARD_COLS];
    memset(board, ' ', BOARD_ROWS * BOARD_COLS);

    int turn, done = 0, turnNext;

    for (turn = 0; turn < BOARD_ROWS * BOARD_COLS && !done; turn++)
    {
        displayWorld(board);
        turnNext = whoseTurnIsNext(board, turn % 2, PIECES);
        // If user enters q then the value should be -1
        if (turnNext == -1)
        {
            // exit the program
            printf("Quitting the game...\n");
            return 0;
        }

        while (!turnNext)
        {
            displayWorld(board);
            puts("**Column full!**\n");
        }
        done = checkWin(board);
    }
    displayWorld(board);

    if (turn == BOARD_ROWS * BOARD_COLS && !done)
    {
        puts("It's a tie!");
    }
    else
    {
        turn--;
        printf("Player %d (%c) wins!\n", turn % 2 + 1, PIECES[turn % 2]);
    }

    return 0;
}
void displayWorld(char *board)
{
    int row, col;

    //system("clear");
    puts("\n ****Connect Four****\n");
    for (row = 0; row < BOARD_ROWS; row++)
    {
        for (col = 0; col < BOARD_COLS; col++)
        {
            printf("| %c ", board[BOARD_COLS * row + col]);
        }
        puts("|");
        puts("-----------------------------");
    }
    puts(" 1 2 3 4 5 6 7\n");
}
int whoseTurnIsNext(char *board, int player, const char *PIECES)
{
    char ch;
    int row, col = 0;
again:
    printf("Player %d (%c):\nEnter letter coordinate (A-G): ", player + 1, PIECES[player]);

    while (1)
    {
        // get a letter from user and if the letter is Q or present in A to G then break the loop
        // toupper function changes the letter from lower alphabet to upper alphabet
        if (scanf("%c", &ch) == 1 && (toupper(ch) == 'Q' || (toupper(ch) >= 'A' && toupper(ch) <= 'G')))
        {
            // Removing extra characters after user's first character input
            while (getchar() != '\n')
                ;
            break;
        }
        else
        {
            // Removing extra characters after user's first character input
            while (getchar() != '\n')
                ;
            puts("Letter out of bounds! Try again.");
        }
    }
    // If user input is Q then return to main function with -1
    if (toupper(ch) == 'Q')
        return -1;

    col = (int)(toupper(ch) - 'A');

    for (row = BOARD_ROWS - 1; row >= 0; row--)
    {
        if (board[BOARD_COLS * row + col] == ' ')
        {
            board[BOARD_COLS * row + col] = PIECES[player];
            return 1;
        }
    }
    if (row == -1)
    {
        printf("\nSelected board coordinate is already full ! Please select different coordinate !\n");
        goto again;
    }
    return 0;
}
int checkWin(char *board)
{
    return (horizontalCheck(board) || verticalCheck(board) || diagonalCheck(board));
}
int checkFour(char *board, int a, int b, int c, int d)
{
    return (board[a] == board[b] && board[b] == board[c] && board[c] == board[d] && board[a] != ' ');
}
int horizontalCheck(char *board)
{
    int row, col, idx;
    const int WIDTH = 1;

    for (row = 0; row < BOARD_ROWS; row++)
    {
        for (col = 0; col < BOARD_COLS - 3; col++)
        {
            idx = BOARD_COLS * row + col;
            if (checkFour(board, idx, idx + WIDTH, idx + WIDTH * 2, idx + WIDTH * 3))
            {
                return 1;
            }
        }
    }
    return 0;
}
int verticalCheck(char *board)
{
    int row, col, idx;
    const int HEIGHT = 7;

    for (row = 0; row < BOARD_ROWS - 3; row++)
    {
        for (col = 0; col < BOARD_COLS; col++)
        {
            idx = BOARD_COLS * row + col;
            if (checkFour(board, idx, idx + HEIGHT, idx + HEIGHT * 2, idx + HEIGHT * 3))
            {
                return 1;
            }
        }
    }
    return 0;
}
int diagonalCheck(char *board)
{
    int row, col, idx, count = 0;
    const int DIAG_RGT = 6, DIAG_LFT = 8;

    for (row = 0; row < BOARD_ROWS - 3; row++)
    {
        for (col = 0; col < BOARD_COLS; col++)
        {
            idx = BOARD_COLS * row + col;
            if (count <= 3 && checkFour(board, idx, idx + DIAG_LFT, idx + DIAG_LFT * 2, idx + DIAG_LFT * 3) || count >= 3 && checkFour(board, idx, idx + DIAG_RGT, idx + DIAG_RGT * 2, idx + DIAG_RGT * 3))
            {
                return 1;
            }
            count++;
        }
        count = 0;
    }
    return 0;
}

Output 1:

Output 2: