if (body[Head_x][Head_y] == -2) { delete food; Food* food; do { food = new Food(20, 30); } while (body[food->getfood_x()][food->getfood_y()] != 0); body[food->getfood_x()][food->getfood_y()] = -2; }帮我改正这段代码，在经历第n次if依然可以实现将body数组的 body[food->getfood_x()][food->getfood_y()] = -2;

你可以使用一个计数器变量 n 来记录经过了多少次 if 条件判断，然后在 while 循环中增加一个退出条件，即 n 达到指定的次数。修改后的代码如下：

int n = 0;
while (n < MAX_N && body[Head_x][Head_y] == -2) {
    delete food;
    Food* food;
    do {
        food = new Food(20, 30);
    } while (body[food->getfood_x()][food->getfood_y()] != 0);
    body[food->getfood_x()][food->getfood_y()] = -2;
    n++;
}

其中，MAX_N 是一个预定义的常量，表示最大允许的尝试次数。如果经过了 MAX_N 次循环仍然没有找到合适的位置放置食物，就会退出循环。这样可以保证在经过多次 if 判断后，仍然能够将食物放在正确的位置上。

相关问题

if (body[Head_x][Head_y] == -2) { delete food; Food* food; do { food = new Food(20, 30); } while (body[food->getfood_x()][food->getfood_y()] != 0); body[food->getfood_x()][food->getfood_y()] = -2; }帮我改正这段代码，在经历多次if依然可以实现

可以将这段代码改成一个 while 循环，这样可以避免使用多个 if 语句，代码如下：

while (body[Head_x][Head_y] == -2) {
    delete food;
    Food* food;
    do {
        food = new Food(20, 30);
    } while (body[food->getfood_x()][food->getfood_y()] != 0);
    body[food->getfood_x()][food->getfood_y()] = -2;
}

这样，只要在 Head_x 和 Head_y 上出现了食物，就会一直循环直到找到一个空位置为止，然后放置食物。

用c++语言，面对对象的思想，写贪吃蛇代码，定义了class Snake { private: int x; int y; Snake* pre; Snake* next; public: Food food; }class Food { private: int food_x; int food_y; char c;//食物的字符表示 public: Food(int x, int y); char getfoodchar(); };，搭配二维数组，画出边跨和蛇，给个示例代码

以下是一个简单的贪吃蛇代码示例，使用了二维数组和面向对象的思想：

#include <iostream>
#include <windows.h>
#include <conio.h>
#include <ctime>
using namespace std;

const int WIDTH = 20;
const int HEIGHT = 20;
const int INTERVAL = 100;

class Snake {
private:
    int x, y;
    Snake* pre;
    Snake* next;
public:
    Snake(int x, int y, Snake* pre = nullptr, Snake* next = nullptr) : x(x), y(y), pre(pre), next(next) {}
    int getX() { return x; }
    int getY() { return y; }
    void setX(int x) { this->x = x; }
    void setY(int y) { this->y = y; }
    Snake* getPre() { return pre; }
    Snake* getNext() { return next; }
    void setPre(Snake* pre) { this->pre = pre; }
    void setNext(Snake* next) { this->next = next; }
};

class Food {
private:
    int x, y;
    char c;
public:
    Food(int x, int y, char c = '@') : x(x), y(y), c(c) {}
    int getX() { return x; }
    int getY() { return y; }
    char getC() { return c; }
    void setX(int x) { this->x = x; }
    void setY(int y) { this->y = y; }
    void setC(char c) { this->c = c; }
};

class Game {
private:
    int map[HEIGHT][WIDTH];
    Snake* head;
    Snake* tail;
    Food* food;
    bool gameover;
    int score;
public:
    Game() : gameover(false), score(0) {
        //初始化地图
        for (int i = 0; i < HEIGHT; i++) {
            for (int j = 0; j < WIDTH; j++) {
                if (i == 0 || i == HEIGHT - 1 || j == 0 || j == WIDTH - 1) {
                    map[i][j] = 1;//边跨
                }
                else {
                    map[i][j] = 0;//空地
                }
            }
        }
        //初始化蛇
        head = new Snake(WIDTH / 2, HEIGHT / 2);
        tail = head;
        map[head->getY()][head->getX()] = 2;//蛇身
        for (int i = 1; i < 3; i++) {
            Snake* body = new Snake(head->getX() + i, head->getY(), tail, nullptr);
            tail->setNext(body);
            tail = body;
            map[body->getY()][body->getX()] = 2;//蛇身
        }
        //初始化食物
        srand((unsigned)time(nullptr));
        food = new Food(rand() % (WIDTH - 2) + 1, rand() % (HEIGHT - 2) + 1);
        map[food->getY()][food->getX()] = 3;//食物
    }
    void draw() {
        system("cls");
        for (int i = 0; i < HEIGHT; i++) {
            for (int j = 0; j < WIDTH; j++) {
                if (map[i][j] == 0) {
                    cout << "  ";//空地
                }
                else if (map[i][j] == 1) {
                    cout << "##";//边跨
                }
                else if (map[i][j] == 2) {
                    cout << "**";//蛇身
                }
                else if (map[i][j] == 3) {
                    cout << food->getC() << " ";//食物
                }
            }
            cout << endl;
        }
        cout << "Score: " << score << endl;
    }
    void update() {
        //移动蛇
        int x = head->getX();
        int y = head->getY();
        switch (_getch()) {
        case 'w':
            y--;
            break;
        case 'a':
            x--;
            break;
        case 's':
            y++;
            break;
        case 'd':
            x++;
            break;
        }
        if (map[y][x] == 1 || map[y][x] == 2) {
            gameover = true;//撞墙或撞身体
            return;
        }
        if (map[y][x] == 3) {
            score += 10;//吃到食物
            food->setX(rand() % (WIDTH - 2) + 1);
            food->setY(rand() % (HEIGHT - 2) + 1);
            map[food->getY()][food->getX()] = 3;//生成新的食物
        }
        else {
            Snake* p = tail;
            map[p->getY()][p->getX()] = 0;//清空尾巴
            tail = p->getPre();
            tail->setNext(nullptr);
            delete p;//删除尾巴
        }
        head->setPre(new Snake(x, y, nullptr, head));
        head = head->getPre();
        map[y][x] = 2;//更新蛇头位置
    }
    bool isGameover() { return gameover; }
};

int main() {
    Game game;
    while (!game.isGameover()) {
        game.draw();
        game.update();
        Sleep(INTERVAL);
    }
    cout << "Game over! Score: " << game.score << endl;
    system("pause");
    return 0;
}

这个示例代码使用了二维数组来表示游戏场景，用数字表示不同的物体，使用Snake和Food类来表示蛇和食物，并且使用了面向对象的思想。在主函数中不断循环调用Game类的draw和update函数来画出场景和更新游戏状态。