C语言用面向对象的思想写贪吃蛇

　　大概一年前这时候，接触C语言一个月，那时候知之甚少，对面向对象只觉”可远观而不可亵玩“，而且会看到很多言论说C语言就是面向过程的语言，C++就是面向对象的语言。不过，不记得什么时候在网上看到过一篇博文，大概是说如何优雅的写C语言。其中颇有印象的就是通过结构的函数指针模拟C++中的类。

　　今天粗略尝试了一下，写的是之前写过的贪吃蛇。的确，用面向对象的思维写让我的思维变的更加清晰，因为这个游戏（以及大多数显示事物）的天然属性就是对象。

　　此外，这次从最关键最核心的写起，如此写起来真是越写越轻松。因为如果关键部分写不出来，其他写的再好也没用。所以这次的顺序大概是：能移动的蛇--->能吃食物并变长--->能判断自己是否死亡--->其他修饰功能。

　　最后，调试无误后。在发布代码前写了写注释。发现自己现在命名编码规范了不少，所以注释也并不多。曾经看到一种观点就是，注释关键部分就足够了，最好的注释就是良好的命名习惯、编码风格和清晰的逻辑。

　　不过，由于没有太多的规划，都是自己在路上零散构思的，代码还是不够紧凑，逻辑还可以优化。

　　头文件

#ifndef _HEAD_H_
#define _HEAD_H_
#include <stdio.h>
#include <windows.h>//
int Score = -1;
typedef struct node1
{
    int x;
    int y;
    struct node1 *next;
}SnakeBody;
typedef struct node2
{
    int x;
    int y;//location
    char Status;
    char Direction;
    void (*MoveUp)(struct node2 *);
    void (*MoveDown)(struct node2 *);
    void (*MoveRight)(struct node2 *);
    void (*MoveLeft)(struct node2 *);
    void (*GrowUp)(struct node2 *);
    int (*IsDie)(struct node2 *);
    SnakeBody *next;
}SnakeHead;
void HideCursor()
{
    CONSOLE_CURSOR_INFO cursor_info = { 1, 0 };
    SetConsoleCursorInfo(GetStdHandle(STD_OUTPUT_HANDLE), &cursor_info);
}
void SetPosition(int x, int y)
{
    COORD pos;
    HANDLE hOutput;
    pos.X = x;
    pos.Y = y;
    hOutput = GetStdHandle(STD_OUTPUT_HANDLE);
    SetConsoleCursorPosition(hOutput, pos);
}
void Print(SnakeHead *H)
{
    SetPosition(H->x, H->y);
    printf("@");//mean snake head
    SnakeBody *temp = H->next;
    while(NULL != temp)
    {
        SetPosition(temp->x, temp->y);
        printf("+");//means snake body
        temp = temp->next;
    }
}
void Move(SnakeHead *H)
{
    SnakeBody *temp = H->next;
    while (NULL != temp->next->next)
    {
        temp = temp->next;
    }
    temp->next->next = H->next;
    H->next = temp->next;
    SetPosition(temp->next->x, temp->next->y);
    printf(" ");
    temp->next = NULL;
    H->next->x = H->x;
    H->next->y = H->y;
}
void _MoveUp(SnakeHead *H)
{
    Move(H);
    H->y--;
}
void _MoveDown(SnakeHead *H)
{
    Move(H);
    H->y++;
}
void _MoveRight(SnakeHead *H)
{
    Move(H);
    H->x++;    
}
void _MoveLeft(SnakeHead *H)
{
    Move(H);
    H->x--;
}
void _GrowUp(SnakeHead *H)
{
    SnakeBody *temp = (SnakeBody *)malloc(sizeof(SnakeBody));
    temp->x = H->x;
    temp->y = H->y;
    temp->next = H->next;
    H->next =  temp;
    switch (H->Direction)
    {
        case 'U':
        {
            H->y--;
            break;
        }
        case 'D':
        {
            H->y++;
            break;
        }
        case 'L':
        {
            H->x--;
            break;
        }
        case 'R':
        {
            H->x++;
            break;
        }
        default:
        {
            break;
        }
    }
    Print(H);
}
const int Left = 3;
const int Right = 34;
const int Top = 3;
const int Bottom = 27;
void BuildWall()
{
    for (int x = Left; x <= Right; x++)
    {
        SetPosition(x, Top);
        printf("-");
        SetPosition(x, Bottom);
        printf("-");
    }
    for (int y = Top; y <= Bottom; y++)
    {
        SetPosition(Left, y);
        printf("|");
        SetPosition(Right, y);
        printf("|");
    }
    //some hint
    SetPosition(15, 1);
    printf("Snake");
    SetPosition(20, 2);
    printf("zhaoyu");
    SetPosition(37, 7);
    printf("F1:Slow Down");
    SetPosition(37, 9);
    printf("F2:Speed Up");
    SetPosition(37, 11);
    printf("F3:Speed Up++");
    SetPosition(37, 15);
    printf("Score:");
}
void CreateFood(int *x, int *y, SnakeHead *H)
{
    int flag = 1;
    int i = 0, j = 0; 
    //make sure in the wall && not on snake
    SnakeBody *temp = H->next;
    while (1 == flag)
    {
        i = rand()%30;
        i += 4;
        j = rand()%24;
        j += 4;
        flag = 0;
        if (i == H->x && j == H->y)
        {
            flag = 1;
            continue;
        }
        temp = H->next;
        while (NULL != temp)
        {
            if (i == temp->x && j == temp->y)
            {
                flag = 1;
                break;
            }
            temp = temp->next;
        }
    }

    *x = i;
    *y = j;
    SetPosition(i, j);
    printf("$");//dollar mead food!
    SetPosition(45, 15);
    //once food created ,score plus 1
    printf("%d", ++Score);
}
int Die(SnakeHead *H)
{
    //out the wall will die
    if (H->x <= Left || H->x >= Right || H->y >= Bottom || H->y <= Top)
    {
        return 1;//die
    }
    // crush into itself will die
    SnakeBody *temp = H->next;
    while (NULL !=temp)
    {
        if (H->x == temp->x && H->y == temp->y)
        {
            return 1;
        }
        temp = temp->next;
    }
    // 0 mean not die
    return 0;
}
#endif

　　源文件

#include "head.h"


void StartGame()
{    
    //Create a snake
    SnakeBody *temp = (SnakeBody *)malloc(sizeof(SnakeBody));
    SnakeHead *Head = (SnakeHead *)malloc(sizeof(SnakeHead));
    Head->Direction = 'L';
    Head->Status = 1;
    Head->x = 10;
    Head->y = 10;
    //assign some functions to snake
    Head->MoveUp = _MoveUp;
    Head->MoveDown = _MoveDown;
    Head->MoveRight = _MoveRight;
    Head->MoveLeft = _MoveLeft;
    Head->GrowUp = _GrowUp;
    Head->IsDie = Die;
    temp->x = 11;
    temp->y = 10;
    temp->next = NULL;
    Head->next = temp;
    // create snake body
    for (int i = 0; i < 5; i++)
    {
        SnakeBody *move = (SnakeBody *)malloc(sizeof(SnakeBody));
        move->x = temp->x + 1;
        move->y = temp->y;
        temp->next = move;
        temp = move;
        move->next = NULL;
    }
    //Init food
    int Foodx = 0, Foody = 0;
    CreateFood(&Foodx, &Foody, Head);
    int Speed = 10;
    while (1 == Head->Status)
    {
        //print the snake
        Print(Head);
        //judge is or not die
        if((*Head->IsDie)(Head))
        {
            break;
        }
        //get direction
        if(GetAsyncKeyState(VK_UP) && 'D' != Head->Direction)
        {
            Head->Direction = 'U';
        }
        else if (GetAsyncKeyState(VK_DOWN) && 'U' != Head->Direction)
        {
            Head->Direction = 'D';
        }
        else if (GetAsyncKeyState(VK_RIGHT) && 'L' != Head->Direction)
        {
            Head->Direction = 'R';
        }
        else if (GetAsyncKeyState(VK_LEFT) && 'R' != Head->Direction)
        {
            Head->Direction = 'L';
        }
        //move
        switch (Head->Direction)
        {
            case 'U':
            {
                //judge is there a food
                if (Head->x == Foodx && Head->y - 1 == Foody)
                {
                    (*Head->GrowUp)(Head);
                    CreateFood(&Foodx, &Foody, Head);
                }
                else//Just move
                {
                    (*Head->MoveUp)(Head);
                }
                break;
            }
            case 'D':
            {
                if (Head->x == Foodx && Head->y + 1 == Foody)
                {
                    (*Head->GrowUp)(Head);
                    CreateFood(&Foodx, &Foody, Head);
                }
                else
                {
                    (*Head->MoveDown)(Head);
                }
                break;
            }
            case 'R':
            {
                if (Head->x + 1 == Foodx && Head->y == Foody)
                {
                    (*Head->GrowUp)(Head);
                    CreateFood(&Foodx, &Foody, Head);
                }
                else
                {
                    (*Head->MoveRight)(Head);    
                }
                
                break;
            }
            case 'L':
            {
                if (Head->x - 1 == Foodx && Head->y == Foody)
                {
                    (*Head->GrowUp)(Head);
                    CreateFood(&Foodx, &Foody, Head);
                }
                else
                {
                    (*Head->MoveLeft)(Head);
                }
                break;
            }
            default:
            {
                break;
            }
        }
        //control 
        if (GetAsyncKeyState(VK_F1) && Speed > 6)
        {
            Speed -= 5;
        }
        else if (GetAsyncKeyState(VK_F2) && Speed < 30)
        {
            Speed += 5;
        }
        else if (GetAsyncKeyState(VK_F3))
        {
            Speed += 10;
        }
        if ('L' == Head->Direction ||'R' == Head->Direction)
        {
            Sleep(1000/Speed);
        }
        else
        {
            Sleep(2000/Speed);
        }
    }
}
int main(int argc, char const *argv[])
{
    //init
    system("cls");
    system("mode con cols=50 lines=30");//no space around equal sign    
    BuildWall();
    HideCursor();
    StartGame();
    SetPosition(36, 20);
    printf("Enter to exit!");
    getchar();
    return 0;
}

 　　运行：

　　　　

　　后记：

　　1、函数指针与函数名

　　函数名与函数指针都是一样的，即都是函数指针。函数名是一个函数指针常量，而函数指针是一个函数数指针变量。

　　一般的C语言书籍都不会谈及这些近乎奇淫技巧的东东。

　　2、GetAsyncKeyState函数

　　这个函数按下之后其状态会一直存在，我在写俄罗斯方块就大受其害。以下面代码为例。你只需要按一下F1就可以跳出循环了，而不是1000下。因为按下一次之后其状态就始终为真了，除非你按下别的键。

#include <stdio.h>
#include <windows.h>
int main(int argc, char const *argv[])
{
    int i = 0;
    while (1)
    {
        if (GetAsyncKeyState(VK_F1))
        {
            i++;
        }
        if (i >= 1000)
        {
            break;
        }
    }
    printf("%d
", i);
    return 0;
}