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Building a Tic-Tac-Toe Game in C
Creating a Tic-Tac-Toe game in C is a fun and educational project that demonstrates how to use arrays, loops, conditionals, and functions. The game will allow two players to take turns placing their markers (X and O) on a 3×3 grid, with the goal of getting three in a row.
Step-by-Step Implementation
- Define the Game Board: Use a 2D array to represent the Tic-Tac-Toe grid.
- Display the Board: Create a function to print the current state of the board.
- Check for Win or Draw: Implement functions to check if a player has won or if the game is a draw.
- Take Player Input: Allow players to choose their position on the board.
- Control the Game Loop: Use a loop to alternate between players until there’s a win or a draw.
Example Code
Here’s a complete implementation of a Tic-Tac-Toe game in C:
#include <stdio.h>
#define SIZE 3 // Define the size of the Tic-Tac-Toe board
// Function prototypes
void printBoard(char board[SIZE][SIZE]);
int checkWin(char board[SIZE][SIZE]);
int checkDraw(char board[SIZE][SIZE]);
void resetBoard(char board[SIZE][SIZE]);
int main() {
char board[SIZE][SIZE]; // Create the game board
int row, col, result;
char currentPlayer = 'X'; // Start with player X
resetBoard(board); // Initialize the board
// Main game loop
while (1) {
printBoard(board); // Display the current board
printf("Player %c, enter your move (row and column): ", currentPlayer);
scanf("%d %d", &row, &col); // Get player input
// Validate the move
if (row < 0 || row >= SIZE || col < 0 || col >= SIZE || board[row][col] != ' ') {
printf("Invalid move. Try again.\n");
continue; // Ask for input again
}
// Place the player's mark on the board
board[row][col] = currentPlayer;
// Check for a win
result = checkWin(board);
if (result == 1) {
printBoard(board);
printf("Player %c wins!\n", currentPlayer);
break;
}
// Check for a draw
if (checkDraw(board)) {
printBoard(board);
printf("It's a draw!\n");
break;
}
// Switch players
currentPlayer = (currentPlayer == 'X') ? 'O' : 'X';
}
return 0;
}
// Function to print the game board
void printBoard(char board[SIZE][SIZE]) {
printf("\n");
for (int i = 0; i < SIZE; i++) {
for (int j = 0; j < SIZE; j++) {
printf(" %c ", board[i][j]);
if (j < SIZE - 1) printf("|");
}
printf("\n");
if (i < SIZE - 1) {
for (int j = 0; j < SIZE; j++) printf("---");
printf("\n");
}
}
printf("\n");
}
// Function to check if a player has won
int checkWin(char board[SIZE][SIZE]) {
// Check rows and columns
for (int i = 0; i < SIZE; i++) {
if ((board[i][0] == board[i][1] && board[i][1] == board[i][2] && board[i][0] != ' ') ||
(board[0][i] == board[1][i] && board[1][i] == board[2][i] && board[0][i] != ' ')) {
return 1; // A player has won
}
}
// Check diagonals
if ((board[0][0] == board[1][1] && board[1][1] == board[2][2] && board[0][0] != ' ') ||
(board[0][2] == board[1][1] && board[1][1] == board[2][0] && board[0][2] != ' ')) {
return 1; // A player has won
}
return 0; // No winner yet
}
// Function to check for a draw
int checkDraw(char board[SIZE][SIZE]) {
for (int i = 0; i < SIZE; i++) {
for (int j = 0; j < SIZE; j++) {
if (board[i][j] == ' ') {
return 0; // There are still moves left
}
}
}
return 1; // The game is a draw
}
// Function to reset the game board
void resetBoard(char board[SIZE][SIZE]) {
for (int i = 0; i < SIZE; i++) {
for (int j = 0; j < SIZE; j++) {
board[i][j] = ' '; // Initialize all positions to empty
}
}
}
Explanation of the Code
- Define Constants: The size of the Tic-Tac-Toe board is defined using a macro.
- Function Prototypes: Functions for printing the board, checking for wins, checking for draws, and resetting the board are declared.
- Main Function:
- Initializes the board and sets the current player to ‘X’.
- Enters a loop where it displays the board, takes player input, and validates the move.
- Calls the appropriate functions to check for wins or draws after each move.
- Switches the current player after each valid move.
- Print Board Function: Displays the current state of the board in a formatted way.
- Check Win Function: Checks all rows, columns, and diagonals for three matching symbols (either ‘X’ or ‘O’).
- Check Draw Function: Checks if all positions on the board are filled without a winner, indicating a draw.
- Reset Board Function: Initializes the board to empty spaces (‘ ‘).
Sample Output
Here’s how the program runs in a terminal:
Player X, enter your move (row and column): 0 0
| |
X |---|
| |
| |
Player O, enter your move (row and column): 1 1
| |
X |---|
| O |
| |
Player X, enter your move (row and column): 0 1
| |
X |---|
X | O |
| |
Player O, enter your move (row and column): 1 0
| |
X |---|
O | O |
| |
Player X, enter your move (row and column): 0 2
| |
X |---|
X | O |
| |
Player X wins!
