Snake Code in C++

Snake is a classic game that includes a growing line represented as a snake that can consume items, change direction, and grow in length. As the snake grows larger in length, the difficulty of the game grows. In this article, we will create a snake game using a C++ program.

Rules to Play Snake Game

• Don’t hit a wall and don’t bite your own tail.
• Crashing into a wall or your tail will end the game immediately.
• 10 points will be added to the player’s score for eating the fruit (#).
• The player’s total score is calculated based on the number of fruits the snake consumed.
• The length of the snake will be increased after eating the fruits.
• Use w, a, s, d to move the snake.

Steps to Write a Snake Game

By following these steps, you will be able to create a fully functional snake game in C++ which can be played in the console using the keyboard.

Step 1: Setting Up The Project

Create a new C++ source file (.cpp) in your desired directory.

Step 2: Including Necessary Libraries

We need 3 different libraries that are:

C++

#include <conio.h>
#include <iostream>
#include <windows.h>

Here,

• iostream: Standard Input and Output Library of C++..
• windows.h: Windows API Library.
• conio.h: Non-Standard Library that contains console commands.

Step 3: Defining Global Variables for the Game

We have to specify some global game variables that we need to be accessible to all the functions. These are:

C++

// height and width of the boundary
const int width = 80;
const int height = 20;

// Snake head coordinates of snake (x-axis, y-axis)
int x, y;
// Food coordinates
int fruitCordX, fruitCordY;
// variable to store the score of he player
int playerScore;
// Array to store the coordinates of snake tail (x-axis,
// y-axis)
int snakeTailX[100], snakeTailY[100];
// variable to store the length of the sanke's tail
int snakeTailLen;
// for storing snake's moving snakesDirection
enum snakesDirection { STOP = 0, LEFT, RIGHT, UP, DOWN };
// snakesDirection variable
snakesDirection sDir;
// boolean variable for checking game is over or not
bool isGameOver;

Step 4: Initializing the Game

Create a function named GameInit() of void type for initializing the game variables.

C++

void GameInit()
{
    isGameOver = false;
    sDir = STOP;
    x = width / 2;
    y = height / 2;
    fruitCordX = rand() % width;
    fruitCordY = rand() % height;
    playerScore = 0;
}

Step 5: Creating Game Board cum Game Rendering Function

Create a function named GameRender() of void type for creating the game board and rendering the game whenever needed in the console.

C++

// Function for creating the game board & rendering
void GameRender(string playerName)
{
    system("cls"); // Clear the console

    // Creating top walls with '-'
    for (int i = 0; i < width + 2; i++)
        cout << "-";
    cout << endl;

    for (int i = 0; i < height; i++) {
        for (int j = 0; j <= width; j++) {
            // Creating side walls with '|'
            if (j == 0 || j == width)
                cout << "|";
            // Creating snake's head with 'O'
            if (i == y && j == x)
                cout << "O";
            // Creating the sanke's food with '#'
            else if (i == fruitCordY && j == fruitCordX)
                cout << "#";
            // Creating snake's head with 'O'
            else {
                bool prTail = false;
                for (int k = 0; k < snakeTailLen; k++) {
                    if (snakeTailX[k] == j
                        && snakeTailY[k] == i) {
                        cout << "o";
                        prTail = true;
                    }
                }
                if (!prTail)
                    cout << " ";
            }
        }
        cout << endl;
    }

    // Creating bottom walls with '-'
    for (int i = 0; i < width + 2; i++)
        cout << "-";
    cout << endl;

    // Display player's score
    cout << playerName << "'s Score: " << playerScore
         << endl;
}

Step 6: Updating the Game State

Create a function named UpdateGame() of void type for updatig the game state after each move.

C++

// Function for updating the game state
void UpdateGame()
{
    int prevX = snakeTailX[0];
    int prevY = snakeTailY[0];
    int prev2X, prev2Y;
    snakeTailX[0] = x;
    snakeTailY[0] = y;

    for (int i = 1; i < snakeTailLen; i++) {
        prev2X = snakeTailX[i];
        prev2Y = snakeTailY[i];
        snakeTailX[i] = prevX;
        snakeTailY[i] = prevY;
        prevX = prev2X;
        prevY = prev2Y;
    }

    switch (sDir) {
    case LEFT:
        x--;
        break;
    case RIGHT:
        x++;
        break;
    case UP:
        y--;
        break;
    case DOWN:
        y++;
        break;
    }

    // Checks for snake's collision with the wall (|)
    if (x >= width || x < 0 || y >= height || y < 0)
        isGameOver = true;

    // Checks for collision with the tail (o)
    for (int i = 0; i < snakeTailLen; i++) {
        if (snakeTailX[i] == x && snakeTailY[i] == y)
            isGameOver = true;
    }

    // Checks for snake's collision with the food (#)
    if (x == fruitCordX && y == fruitCordY) {
        playerScore += 10;
        fruitCordX = rand() % width;
        fruitCordY = rand() % height;
        snakeTailLen++;
    }
}

Step 7: Setting the Game Difficulty

Create a function named SetDifficulty() of int type for setting up the game difficulty(returns a int variable ‘dfc’).

C++

// Function to set the game difficulty level
int SetDifficulty()
{
    int dfc, choice;
    cout << "\nSET DIFFICULTY\n1: Easy\n2: Medium\n3: hard "
            "\nNOTE: if not chosen or pressed any other "
            "key, the difficulty will be automatically set "
            "to medium\nChoose difficulty level: ";
    cin >> choice;
    switch (choice) {
    case '1':
        dfc = 50;
        break;
    case '2':
        dfc = 100;
        break;
    case '3':
        dfc = 150;
        break;
    default:
        dfc = 100;
    }
    return dfc;
}

Step 8: Handling User Input

Create a function named UserInput() of void type for getting the user input for playing the game.

C++

// Function to handle user UserInput
void UserInput()
{
    // Checks if a key is pressed or not
    if (_kbhit()) {
        // Getting the pressed key
        switch (_getch()) {
        case 'a':
            sDir = LEFT;
            break;
        case 'd':
            sDir = RIGHT;
            break;
        case 'w':
            sDir = UP;
            break;
        case 's':
            sDir = DOWN;
            break;
        case 'x':
            isGameOver = true;
            break;
        }
    }
}

Note:

1._kbhit() function checks the console for a recent keystroke. If the function returns a nonzero value, a keystroke is waiting in the buffer. The program can then call _getch() or _getche() to get the keystroke.

2. getch()is a nonstandard function and is present in file which is mostly used by. It is not part of the C standard library or ISO C, nor is it defined by POSIX

Step 9: Creating Main Function

Create a loop in the main() function to continuously update the game state, render the game, and handle user input.

C++

// Main function / game looping function
int main()
{
    string playerName;
    cout << "enter your name: ";
    cin >> playerName;
    int dfc = SetDifficulty();

    GameInit();
    while (!isGameOver) {
        GameRender(playerName);
        UserInput();
        UpdateGame();
        // creating a delay for according to the chosen
        // difficulty
        Sleep(dfc);
    }

    return 0;
}

C++ Program to Implement Snake Game

C++

// required header file
#include <conio.h>
#include <iostream>
#include <windows.h>
using namespace std;

// height and width of the boundary
const int width = 80;
const int height = 20;

// Snake head coordinates of snake (x-axis, y-axis)
int x, y;
// Food coordinates
int fruitCordX, fruitCordY;
// variable to store the score of he player
int playerScore;
// Array to store the coordinates of snake tail (x-axis,
// y-axis)
int snakeTailX[100], snakeTailY[100];
// variable to store the length of the sanke's tail
int snakeTailLen;
// for storing snake's moving snakesDirection
enum snakesDirection { STOP = 0, LEFT, RIGHT, UP, DOWN };
// snakesDirection variable
snakesDirection sDir;
// boolean variable for checking game is over or not
bool isGameOver;

// Function to initialize game variables
void GameInit()
{
    isGameOver = false;
    sDir = STOP;
    x = width / 2;
    y = height / 2;
    fruitCordX = rand() % width;
    fruitCordY = rand() % height;
    playerScore = 0;
}

// Function for creating the game board & rendering
void GameRender(string playerName)
{
    system("cls"); // Clear the console

    // Creating top walls with '-'
    for (int i = 0; i < width + 2; i++)
        cout << "-";
    cout << endl;

    for (int i = 0; i < height; i++) {
        for (int j = 0; j <= width; j++) {
            // Creating side walls with '|'
            if (j == 0 || j == width)
                cout << "|";
            // Creating snake's head with 'O'
            if (i == y && j == x)
                cout << "O";
            // Creating the sanke's food with '#'
            else if (i == fruitCordY && j == fruitCordX)
                cout << "#";
            // Creating snake's head with 'O'
            else {
                bool prTail = false;
                for (int k = 0; k < snakeTailLen; k++) {
                    if (snakeTailX[k] == j
                        && snakeTailY[k] == i) {
                        cout << "o";
                        prTail = true;
                    }
                }
                if (!prTail)
                    cout << " ";
            }
        }
        cout << endl;
    }

    // Creating bottom walls with '-'
    for (int i = 0; i < width + 2; i++)
        cout << "-";
    cout << endl;

    // Display player's score
    cout << playerName << "'s Score: " << playerScore
         << endl;
}

// Function for updating the game state
void UpdateGame()
{
    int prevX = snakeTailX[0];
    int prevY = snakeTailY[0];
    int prev2X, prev2Y;
    snakeTailX[0] = x;
    snakeTailY[0] = y;

    for (int i = 1; i < snakeTailLen; i++) {
        prev2X = snakeTailX[i];
        prev2Y = snakeTailY[i];
        snakeTailX[i] = prevX;
        snakeTailY[i] = prevY;
        prevX = prev2X;
        prevY = prev2Y;
    }

    switch (sDir) {
    case LEFT:
        x--;
        break;
    case RIGHT:
        x++;
        break;
    case UP:
        y--;
        break;
    case DOWN:
        y++;
        break;
    }

    // Checks for snake's collision with the wall (|)
    if (x >= width || x < 0 || y >= height || y < 0)
        isGameOver = true;

    // Checks for collision with the tail (o)
    for (int i = 0; i < snakeTailLen; i++) {
        if (snakeTailX[i] == x && snakeTailY[i] == y)
            isGameOver = true;
    }

    // Checks for snake's collision with the food (#)
    if (x == fruitCordX && y == fruitCordY) {
        playerScore += 10;
        fruitCordX = rand() % width;
        fruitCordY = rand() % height;
        snakeTailLen++;
    }
}

// Function to set the game difficulty level
int SetDifficulty()
{
    int dfc, choice;
    cout << "\nSET DIFFICULTY\n1: Easy\n2: Medium\n3: hard "
            "\nNOTE: if not chosen or pressed any other "
            "key, the difficulty will be automatically set "
            "to medium\nChoose difficulty level: ";
    cin >> choice;
    switch (choice) {
    case '1':
        dfc = 50;
        break;
    case '2':
        dfc = 100;
        break;
    case '3':
        dfc = 150;
        break;
    default:
        dfc = 100;
    }
    return dfc;
}

// Function to handle user UserInput
void UserInput()
{
    // Checks if a key is pressed or not
    if (_kbhit()) {
        // Getting the pressed key
        switch (_getch()) {
        case 'a':
            sDir = LEFT;
            break;
        case 'd':
            sDir = RIGHT;
            break;
        case 'w':
            sDir = UP;
            break;
        case 's':
            sDir = DOWN;
            break;
        case 'x':
            isGameOver = true;
            break;
        }
    }
}

// Main function / game looping function
int main()
{
    string playerName;
    cout << "enter your name: ";
    cin >> playerName;
    int dfc = SetDifficulty();

    GameInit();
    while (!isGameOver) {
        GameRender(playerName);
        UserInput();
        UpdateGame();
        // creating a delay for according to the chosen
        // difficulty
        Sleep(dfc);
    }

    return 0;
}

Output/Game Screenshots

1. Entering the Player’s Name and Choosing the Difficulty.

2. Initial State of the Game

3. Game Termination When Snake Collides with the Wall

4. Game Termination when Snake Collides with its Own Tail