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 = -;
 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 = { ,  };
     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 = ;
 const int Right = ;
 const int Top = ;
 const int Bottom = ;
 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(, );
     printf("Snake");
     SetPosition(, );
     printf("zhaoyu");
     SetPosition(, );
     printf("F1:Slow Down");
     SetPosition(, );
     printf("F2:Speed Up");
     SetPosition(, );
     printf("F3:Speed Up++");
     SetPosition(, );
     printf("Score:");
 }
 void CreateFood(int *x, int *y, SnakeHead *H)
 {
     int flag = ;
     int i = , j = ;
     //make sure in the wall && not on snake
     SnakeBody *temp = H->next;
     while ( == flag)
     {
         i = rand()%;
         i += ;
         j = rand()%;
         j += ;
         flag = ;
         if (i == H->x && j == H->y)
         {
             flag = ;
             continue;
         }
         temp = H->next;
         while (NULL != temp)
         {
             if (i == temp->x && j == temp->y)
             {
                 flag = ;
                 break;
             }
             temp = temp->next;
         }
     }

     *x = i;
     *y = j;
     SetPosition(i, j);
     printf("$");//dollar mead food!
     SetPosition(, );
     //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 ;//die
     }
     // crush into itself will die
     SnakeBody *temp = H->next;
     while (NULL !=temp)
     {
         if (H->x == temp->x && H->y == temp->y)
         {
             return ;
         }
         temp = temp->next;
     }
     // 0 mean not die
     return ;
 }
 #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 = ;
     Head->x = ;
     Head->y = ;
     //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 = ;
     temp->y = ;
     temp->next = NULL;
     Head->next = temp;
     // create snake body
     for (int i = ; i < ; i++)
     {
         SnakeBody *move = (SnakeBody *)malloc(sizeof(SnakeBody));
         move->x = temp->x + ;
         move->y = temp->y;
         temp->next = move;
         temp = move;
         move->next = NULL;
     }
     //Init food
     int Foodx = , Foody = ;
     CreateFood(&Foodx, &Foody, Head);
     int Speed = ;
     while ( == 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 -  == Foody)
                 {
                     (*Head->GrowUp)(Head);
                     CreateFood(&Foodx, &Foody, Head);
                 }
                 else//Just move
                 {
                     (*Head->MoveUp)(Head);
                 }
                 break;
             }
             case 'D':
             {
                 if (Head->x == Foodx && Head->y +  == Foody)
                 {
                     (*Head->GrowUp)(Head);
                     CreateFood(&Foodx, &Foody, Head);
                 }
                 else
                 {
                     (*Head->MoveDown)(Head);
                 }
                 break;
             }
             case 'R':
             {
                 if (Head->x +  == Foodx && Head->y == Foody)
                 {
                     (*Head->GrowUp)(Head);
                     CreateFood(&Foodx, &Foody, Head);
                 }
                 else
                 {
                     (*Head->MoveRight)(Head);
                 }

                 break;
             }
             case 'L':
             {
                 if (Head->x -  == Foodx && Head->y == Foody)
                 {
                     (*Head->GrowUp)(Head);
                     CreateFood(&Foodx, &Foody, Head);
                 }
                 else
                 {
                     (*Head->MoveLeft)(Head);
                 }
                 break;
             }
             default:
             {
                 break;
             }
         }
         //control
         if (GetAsyncKeyState(VK_F1) && Speed > )
         {
             Speed -= ;
         }
         else if (GetAsyncKeyState(VK_F2) && Speed < )
         {
             Speed += ;
         }
         else if (GetAsyncKeyState(VK_F3))
         {
             Speed += ;
         }
         if ('L' == Head->Direction ||'R' == Head->Direction)
         {
             Sleep(/Speed);
         }
         else
         {
             Sleep(/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(, );
     printf("Enter to exit!");
     getchar();
     return ;
 }

　　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 = ;
     while ()
     {
         if (GetAsyncKeyState(VK_F1))
         {
             i++;
         }
         if (i >= )
         {
             break;
         }
     }
     printf("%d\n", i);
     return ;
 }