Question

我已经开始用C ++编写Snake的代码。到目前为止，这是我的代码。

main.cpp：

#include "game.hpp"

int main(void)
{
    Game game;

    int count = 0;  

    while(game.program_is_running)
    {
        game.key_events();

        if(count >= 3000)
        {
            game.tick();
            count = 0;
        }
        else
            count++;
    }

    return 0;
}

game.hpp：

#include <iostream>
#include <conio.h>
#include <stdlib.h>
#include <vector>

#include "snake.hpp"

#define NUMBER_OF_ROWS 25
#define NUMBER_OF_COLUMNS 25

class Game
{
public:

    Game(void);

    void tick(void);
    void key_events(void);

    bool program_is_running;

private:

    char grid[NUMBER_OF_ROWS][NUMBER_OF_COLUMNS];

    Snake snake;

    bool right_pressed, left_pressed, down_pressed, up_pressed;

    void display_grid(void);
};

Game::Game(void)
{
    for(int y = 0; y < NUMBER_OF_ROWS; y++)
    {
        for(int x = 0; x < NUMBER_OF_COLUMNS; x++)
        {
            if(y == 0 || y == NUMBER_OF_ROWS - 1)
                grid[y][x] = '#';
            else if(x == 0 || x == NUMBER_OF_COLUMNS - 1)
                grid[y][x] = '#';
            else
                grid[y][x] = ' ';
        }
    }

    program_is_running = true;

    right_pressed = false;
    left_pressed = false;
    down_pressed = false;
    up_pressed = false;
}

void Game::tick(void)
{
    for(int y = 0; y < NUMBER_OF_ROWS; y++)
    {
        for(int x = 0; x < NUMBER_OF_COLUMNS; x++)
        {
            if(y == 0 || y == NUMBER_OF_ROWS - 1)
                grid[y][x] = '#';
            else if(x == 0 || x == NUMBER_OF_COLUMNS - 1)
                grid[y][x] = '#';
            else
                grid[y][x] = ' ';
        }
    }

    std::vector<Block> snake_body = snake.get_body();

    if(right_pressed)
    {
        snake.move(0, 1);
    }
    else if(left_pressed)
    {
        snake.move(0, -1);
    }
    else if(down_pressed)
    {
        snake.move(1, 0);
    }
    else if(up_pressed)
    {
        snake.move(-1, 0);
    }

    for(int y = 0; y < NUMBER_OF_ROWS; y++)
    {
        for(int x = 0; x < NUMBER_OF_COLUMNS; x++)
        {
            for(int i = 0; i < snake_body.size(); i++)
            {
                if(snake_body[i].y == y && snake_body[i].x == x)
                {
                    grid[y][x] = snake.get_symbol();
                }
            }
        }
    }

    display_grid();
}

void Game::key_events(void)
{
    char c;

    if(kbhit())
    {
        c = _getch();

        switch(c)
        {
            case 'q':
                program_is_running = false;

            case 'l':
                left_pressed = false;
                down_pressed = false;
                up_pressed = false;
                right_pressed = true;

            case 'h':
                right_pressed = false;
                down_pressed = false;
                up_pressed = false;
                left_pressed = true;

            case 'j':
                right_pressed = false;
                left_pressed = false;
                up_pressed = false;
                down_pressed = true;

            case 'k':
                right_pressed = false;
                down_pressed = false;
                left_pressed = false;
                up_pressed = true;
        }
    }
}

void Game::display_grid(void)
{
    system("cls");

    for(int y = 0; y < NUMBER_OF_ROWS; y++)
    {
        for(int x = 0; x < NUMBER_OF_COLUMNS; x++)
        {
            std::cout << grid[y][x] << ' ';
        }

        std::cout << std::endl;
    }
}

snake.hpp：

#include <vector>

struct Block
{
    int y, x;
};

class Snake
{
public:

    Snake();

    std::vector<Block> get_body();
    char get_symbol(void);

    void add_block(int, int);
    void move(int, int);

private:

    std::vector<Block> body;
    char symbol;
};

Snake::Snake(void)
{
    symbol = 'X';

    add_block(12, 12);
}

std::vector<Block> Snake::get_body()
{
    return body;
}

char Snake::get_symbol(void)
{
    return symbol;
}

void Snake::add_block(int y, int x)
{
    Block block;
    block.y = y;
    block.x = x;
    body.push_back(block);
}

void Snake::move(int y, int x)
{
    body[0].y += y;
    body[0].x += x;
}

此刻，我只是想让蛇通过键k，j，h和l上下，左右移动。无论您按四个键中的哪一个，蛇都只会向上移动。为什么是这样？另外，如果有人可以就程序的结构提出建议，我将不胜感激。

Answer 1

开关

switch(c)
{
    case 'q':
        program_is_running = false;

    case 'l':
        left_pressed = false;
        down_pressed = false;
        up_pressed = false;
        right_pressed = true;

    case 'h':
        right_pressed = false;
        down_pressed = false;
        up_pressed = false;
        left_pressed = true;

    case 'j':
        right_pressed = false;
        left_pressed = false;
        up_pressed = false;
        down_pressed = true;

    case 'k':
        right_pressed = false;
        down_pressed = false;
        left_pressed = false;
        up_pressed = true;
}

总是遇到最后一种情况，'k'，所以您总是以

结尾

        right_pressed = false;
        down_pressed = false;
        left_pressed = false;
        up_pressed = true;

在每种情况下，您都应该添加break，以避免这种情况。

就样式而言，我想知道是否可以将四个互斥事件的四个布尔值折叠成一个标志，以显示要移动的值？

您可以拥有一个查找表（无序映射或类似的表），将键映射到move参数，然后仅调用move而不需要switch语句。

Answer 2

你没有休息；在您的情况之后：因此，您的switch语句将在每种情况下执行，并且由于“ up”是最后一种情况，因此它将覆盖所有其他情况。

为什么我的蛇只向上移动？

2 个答案: