.gitignore

#include <SDL.h>
#include <cstdlib>
#include <iostream>

using namespace std;

const int HEIGHT = 800;
const int WIDTH = 800;
const int tail_max = 1000;
int score;

struct Food {
    int FoodX, FoodY; //coordinate of food
    int size = 10;
    void generateFood() {
        FoodX = rand() % (WIDTH / size);
        FoodY = rand() % (HEIGHT / size);
    }

    void draw(SDL_Renderer* renderer) { //draw food
        SDL_Rect rect;
        rect.w = size;
        rect.h = size;
        rect.x = size * FoodX;
        rect.y = size * FoodY;
        SDL_SetRenderDrawColor(renderer, 0, 255, 0, 255);
        SDL_RenderFillRect(renderer, &rect);
    }

};

struct PosAndVel {
    int x, y; //position
    int stepX = 0, stepY = 0; //velocity
};

struct Snake {
    PosAndVel position; //coordinate of the snake
    PosAndVel velocity; //speed of the snake (which has directions)
    int size = 10;
    int tail_start, tail_end; //head, //tail
    PosAndVel tail[tail_max];
    int tail_length = 1000;
    void move() {
        position.x += velocity.stepX;
        position.y += velocity.stepY;
    }
    void update(Food& food) {
            tail_start++;
            tail_end++;
            tail[tail_end % tail_max] = position;
            position.x += velocity.x;
            position.y += velocity.y;
            if (position.x == food.FoodX && position.y == food.FoodY) {
                tail_length++;
                tail_start--;
                food.generateFood();
                score++;
                cout << score << ":" << " " << endl;
            }
            for (int i = 0; i < tail_length; i++) {
                PosAndVel& tail_position = tail[(tail_start + i) % tail_max];
                if (tail_position.x == position.x && tail_position.y == position.y) {
                    //lose
                    tail_length = 0;
                    tail_start = tail_end;
                }
            }
        }
    void draw(SDL_Renderer* renderer, Food& food) {
        SDL_SetRenderDrawColor(renderer, 255, 255, 255, 255);
        for (int i = 0; i < tail_length; i++) {
            PosAndVel& tail_position = tail[(tail_start + i) % tail_max];
            SDL_Rect rect{size * tail_position.x, size * tail_position.y, size, size};
            SDL_RenderFillRect(renderer, &rect);
        }
        SDL_Rect rect{size * position.x, size * position.y, size, size};
        SDL_RenderFillRect(renderer, &rect);
    }
};

int main(int argc, char* argv[])
{
    SDL_Init(SDL_INIT_EVERYTHING);
    SDL_Window* window = SDL_CreateWindow("Snake Game!", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, HEIGHT, WIDTH, SDL_WINDOW_SHOWN);
    SDL_Renderer* renderer = SDL_CreateRenderer(window, -1, SDL_RENDERER_ACCELERATED);
    SDL_Event e;
    bool Isrunning = true;
    Snake snake = {};
    Food food = {};
    food.generateFood();
    while(Isrunning) {
        snake.move();
        SDL_Delay(75);
        while (SDL_PollEvent(&e)) {
            if (e.type == SDL_QUIT) {
                Isrunning = false;
            }
            if (e.type == SDL_KEYDOWN) {
                switch (e.key.keysym.sym) {
                case SDLK_ESCAPE:
                    Isrunning = false;
                    break;
                case SDLK_UP:
                    snake.velocity.y = -1;
                    snake.velocity.x = 0;
                    break;
                case SDLK_DOWN:
                    snake.velocity.y = 1;
                    snake.velocity.x = 0;
                    break;
                case SDLK_LEFT:
                    snake.velocity.y = 0;
                    snake.velocity.x = -1;
                    break;
                case SDLK_RIGHT:
                    snake.velocity.y = 0;
                    snake.velocity.x = 1;
                    break;
                default:
                    break;
                }
            }
        }
        snake.update(food);
        SDL_SetRenderDrawColor(renderer, 0, 0, 0, 255);
        SDL_RenderClear(renderer);

        snake.draw(renderer, food);
        food.draw(renderer);

        SDL_RenderPresent(renderer);
    }

    return 0;
}