求助！！！C语言版的贪吃蛇问题，谢谢。

[swustpeng]

自己写的C语言版的贪吃蛇，我想知道为什么不能立马掉头转弯回去，而是空一行。别人写的可以。
我的如下图，不知道为什么，头疼。代码贴在下面了。谢谢！

相应符号我做了替换

#include<stdio.h>
#include<stdlib.h>
#include<windows.h>
#include<conio.h>
#include<time.h>

#define Wid 40
#define Hei 20
int speed;//蛇的速度
//蛇的节点 
typedef struct Snake_node{
	COORD pos;
	struct Snake_node *next;
	struct Snake_node *prev;
}Snake,*PSnake;
PSnake Head;//蛇的头指针 
PSnake Tail;//蛇的尾指针 

struct Snake_pos{
	COORD pos;
	int dir;
}HeadPos;//蛇头即将移动的方向和坐标 

COORD Food;//食物坐标
int score;//积分记录 
//光标定位 
void GetPosition(COORD pos)
{
	HANDLE hout=GetStdHandle(STD_OUTPUT_HANDLE);
	SetConsoleCursorPosition(hout,pos);
}
//游戏玩家积分等级输出 
void GameLevel()
{
	COORD pos_1={Wid+2,11}; 
	GetPosition(pos_1);
	if(score>=70)
	{
		printf("当前游戏等级：恭喜你登顶了"); 
	}
	else if(score>=60)
	{
		printf("当前游戏等级：最强蛇人2颗心"); 
	}
	else if(score>=55)
	{
		printf("当前游戏等级：最强蛇人1颗心"); 
	}
	else if(score>=50)
	{
		printf("当前游戏等级：一代宗师3颗心"); 
	}
	else if(score>=45)
	{
		printf("当前游戏等级：一代宗师2颗心"); 
	}
	else if(score>=40)
	{
		printf("当前游戏等级：一代宗师1颗心"); 
	}
	else if(score>=36)
	{
		printf("当前游戏等级：炉火纯青3颗心"); 
	}
	else if(score>=32)
	{
		printf("当前游戏等级：炉火纯青2颗心"); 
	}
	else if(score>=28)
	{
		printf("当前游戏等级：炉火纯青1颗心"); 
	}
	else if(score>=24)
	{
		printf("当前游戏等级：马马虎虎3颗星");
	} 
	else if(score>=19)
	{
		printf("当前游戏等级：马马虎虎2颗星"); 
	}
	else if(score>=16)
	{
		printf("当前游戏等级：马马虎虎1颗星"); 
	}
	else if(score>=13)
	{
		printf("当前游戏等级：初学乍练3颗星"); 
	}
	else if(score>=10)
	{
		printf("当前游戏等级：初学乍练2颗星"); 
	}
	else if(score>=0)
	{
		printf("当前游戏等级：初学乍练1颗星"); 
	}	
}
//添加蛇的头节点 
void AddSnakeBody(COORD pos)
{
	GetPosition(pos);
	printf("蛇");
	PSnake q=(PSnake)malloc(sizeof(Snake));
	q->pos=pos;
	if(Head==NULL&Tail==NULL)
	{
		Head=Tail=q;
		q->next=NULL;
	}
	else
	{
		q->next=Head;
		Head->prev=q;
		Head=q;
	}
	
	COORD pos_1={Wid+2,2};
	GetPosition(pos_1);
	printf("          ");
	GetPosition(pos_1);
	printf("蛇头位置：%d行 %d列",pos.Y,pos.X/2);
}
//删掉蛇的尾节点 
void ReduceSnakeTail()
{
	GetPosition(Tail->pos);
	printf("  ");
	Tail=Tail->prev;
	free(Tail->next);
	Tail->next=NULL;
}
//蛇的移动 
void MoveSnake(COORD pos)
{
	AddSnakeBody(pos);
	ReduceSnakeTail();
}
//方向控制 
void ChangeDir()
{
	COORD pos_1={Wid+2,4};
	if(_kbhit())
	{
		switch(_getch())
		{
			case 72:
				if(HeadPos.dir!=1)
				{
					HeadPos.dir=0;
				}
				break;
			case 80:
				if(HeadPos.dir!=0)
				{
					HeadPos.dir=1;
				}
				break;
			case 75:
				if(HeadPos.dir!=3)
				{
					HeadPos.dir=2;
				}
				break;
			case 77:
				if(HeadPos.dir!=2)
				{
					HeadPos.dir=3;
				}
				break;
			case 'a':
				pos_1.Y=8;
				GetPosition(pos_1);
				system("pause");
				GetPosition(pos_1);
				printf("                ");
				GetPosition(pos_1);
				printf("按a键暂停游戏");
				break; 
			case '5':
				speed=50;
				GetPosition(pos_1);
				printf("当前模式：噩梦");
				break; 
			case '4':
				speed=100;
				GetPosition(pos_1);
				printf("当前模式：困难");
				break;
			case '3':
				speed=150;
				GetPosition(pos_1);
				printf("当前模式：一般");
				break;
			case '2':
				speed=200;
				GetPosition(pos_1);
				printf("当前模式：简单");
				break;
			case '1':
				speed=400;
				GetPosition(pos_1);
				printf("当前模式：蜗牛");
				break;
		}
	}
	switch (HeadPos.dir)
	{
		case 0:
			HeadPos.pos.Y--;
			break;
		case 1:
			HeadPos.pos.Y++;
			break;
		case 2:
			HeadPos.pos.X-=2;
			break;
		case 3:
			HeadPos.pos.X+=2;
			break;
	}
}
//划出游戏边框 
void DrawBorder()
{
	COORD pos;
	for(pos.Y=0;pos.Y<=Hei-1;pos.Y++)
	{
		GetPosition(pos);
		for(pos.X=0;pos.X<=Wid-2;pos.X+=2)
		{
			if(pos.Y==0||pos.Y==Hei-1||pos.X==0||pos.X==Wid-2)
			{
				printf("墙");
			}
			else
			{
				printf("  ");
			}
		}
		pos.X=0;
	}
	
	
	COORD pos_1={Wid+2,4};
	GetPosition(pos_1);
	printf("模式选择提示：按键1~5分别对应傻瓜、简单、一般、困难、噩梦");
	pos_1.Y++;
	GetPosition(pos_1);
	printf("游戏过程中，模式可以随意切换,请君量力而行！");
	pos_1.Y++;
	GetPosition(pos_1);
	printf("当前模式：一般");
	speed=150;
	pos_1.Y=8;
	GetPosition(pos_1);
	printf("按a键暂停游戏"); 
	pos_1.Y=0;
	GetPosition(pos_1);
	printf("贪吃蛇游戏");
	pos_1.Y=12; 
	GetPosition(pos_1);
	printf("想要知道最高等级是什么吗？那就继续玩游戏吧！");
	pos_1.Y=Hei-3;
	GetPosition(pos_1);
	printf("开发者信息：xxxxxx"); 
	
}
//游戏结束判断 
int GameOver()
{
	if(HeadPos.pos.X<=0||HeadPos.pos.X>=Wid-2||HeadPos.pos.Y<=0||HeadPos.pos.Y>=Hei-1)
	{
		return 1;
	}
	PSnake q=Head;
	while(q!=NULL)
	{
		if(HeadPos.pos.X==q->pos.X&&HeadPos.pos.Y==q->pos.Y)
		{
			return 1;
		}
		q=q->next;
	}
	return 0;
}
//食物和积分信息输出 
void FoodInfo()
{
	COORD pos={Wid+2,1};
	GetPosition(pos);
	printf("          ");
	GetPosition(pos);
	printf("食物位置：%d行 %d列",Food.Y,Food.X/2);
	pos.Y=9;
	GetPosition(pos);
	printf("当前得分：%d",score++);
}
//初始化食物 
int InitFood()
{
	srand((unsigned) time(NULL));
	while(1)
	{
		Food.X=(rand()%(Wid/2-2)+1)*2;
		Food.Y=rand()%(Hei-2)+1;
		int flag=0;
		PSnake q=Head;
		while(q!=NULL)
		{
			if(Food.X==q->pos.X&&Food.Y==q->pos.Y)
			{
				flag=1;
				break; 
			}
			q=q->next;
		}
		if(flag==0)
		{
			break;
		}
	}
	
	GetPosition(Food);
	printf("食");
	GameLevel();
	FoodInfo();
}
//考虑到内存问题，链表空间释放（重新开始游戏需要用到） 
void DestroySnakeNode()
{
	while(Tail!=Head)
	{
		Tail=Tail->prev;
		free(Tail->next);
	}
	free(Tail);
}
//游戏数据初始化 
void InitGame()
{
	system("color 0E");
	DrawBorder();
	HeadPos.pos.X=Wid/2;
	HeadPos.pos.Y=Hei/2;
	HeadPos.dir=0;
	Head=NULL;
	Tail=NULL; 
	AddSnakeBody(HeadPos.pos);
	InitFood();
	score=0;
}
//游戏运行控制 
void RunGame()
{
	while(1)
	{
		Sleep(speed);
		ChangeDir();
		if(GameOver())
		{
			break;
		}
		else if(HeadPos.pos.X==Food.X&&HeadPos.pos.Y==Food.Y)
		{
			AddSnakeBody(HeadPos.pos);
			InitFood();
		}
		else
		{
			MoveSnake(HeadPos.pos);
		}
	}
	COORD pos={0,Hei};
	GetPosition(pos);
	printf("很遗憾，你撞墙了或者自食自己，游戏结束!\n");
}
//游戏重新开始 
int RestarGame()
{
	int restar; 
	printf("你是最棒的！是否重新挑战游戏？\n");
	printf("0.否 1.是\n");
	printf("请选择（按回车键确认）：");
	scanf("%d",&restar);
	if(restar==1)
	{
		system("cls");
		DestroySnakeNode();
		return 1;
	}
	else if(restar==0)
	{
		printf("游戏退出！\n");
		return 0;
	}
	else
	{

		printf("选择无效！默认退出！\n");
		return 0;
	}
}


int  main()
{
	while(1)
	{
		InitGame();
		RunGame(); 
		if(RestarGame())
		{
			continue;
		}
		break;
	}
	return 0;
}

[yiyefangzhou24]

单步调试是程序员的基本技能，转弯的时候下个断点看一下

[赵4老师]

仅供参考：

#include <conio.h>
#include <windows.h>

void ConPrintAt(int x, int y, char *CharBuffer, int len)
{
   DWORD count;
   COORD coord = {x, y};
   HANDLE hStdOut = GetStdHandle(STD_OUTPUT_HANDLE);
   SetConsoleCursorPosition(hStdOut, coord);
   WriteConsole(hStdOut, CharBuffer, len, &count, NULL);
}
void HideTheCursor()
{
   CONSOLE_CURSOR_INFO cciCursor;
   HANDLE hStdOut = GetStdHandle(STD_OUTPUT_HANDLE);

   if(GetConsoleCursorInfo(hStdOut, &cciCursor))
   {
      cciCursor.bVisible = FALSE;
      SetConsoleCursorInfo(hStdOut, &cciCursor);
   }
}

void ShowTheCursor()
{
   CONSOLE_CURSOR_INFO cciCursor;
   HANDLE hStdOut = GetStdHandle(STD_OUTPUT_HANDLE);

   if(GetConsoleCursorInfo(hStdOut, &cciCursor))
   {
      cciCursor.bVisible = TRUE;
      SetConsoleCursorInfo(hStdOut, &cciCursor);
   }
}
void GetWH(int *w,int *h) {
    HANDLE hStdOut = GetStdHandle(STD_OUTPUT_HANDLE);
    CONSOLE_SCREEN_BUFFER_INFO csbi;
    if (GetConsoleScreenBufferInfo(hStdOut, &csbi)) {
        *w=csbi.srWindow.Right;
        *h=csbi.srWindow.Bottom;
    } else {
        *w=80;
        *h=25;
    }
}
void ClearConsole()
{
   //Get the handle to the current output buffer...
   HANDLE hStdOut = GetStdHandle(STD_OUTPUT_HANDLE);
   //This is used to reset the carat/cursor to the top left.
   COORD coord = {0, 0};
   //A return value... indicating how many chars were written
   //   not used but we need to capture this since it will be
   //   written anyway (passing NULL causes an access violation).
   DWORD count;
   //This is a structure containing all of the console info
   // it is used here to find the size of the console.
   CONSOLE_SCREEN_BUFFER_INFO csbi;
   //Here we will set the current color
   if(GetConsoleScreenBufferInfo(hStdOut, &csbi))
   {
      //This fills the buffer with a given character (in this case 32=space).
      FillConsoleOutputCharacter(hStdOut, (TCHAR) 32, csbi.dwSize.X * csbi.dwSize.Y, coord, &count);
      FillConsoleOutputAttribute(hStdOut, csbi.wAttributes, csbi.dwSize.X * csbi.dwSize.Y, coord, &count);
      //This will set our cursor position for the next print statement.
      SetConsoleCursorPosition(hStdOut, coord);
   }
}

int main() {
    unsigned short k;
    int x,y,w,h;
    char d;

    SetConsoleOutputCP(437);
    ClearConsole();
    GetWH(&w,&h);
    x=w/2;y=h/2;
    HideTheCursor();
    ConPrintAt(x,y,"O",1);
    d='o';
    while (1) {
        Sleep(50);
        if (kbhit()) {
            k=getch();
            if (27==k) break;//按Esc键退出
            if (0==k||0xe0==k) k|=getch()<<8;//非字符键
            switch (k) {
                case 0x48e0:case 0x04800://上
                    d='u';
                    if (y>0) {
                        ConPrintAt(x,y," ",1);
                        y--;
                        ConPrintAt(x,y,"O",1);
                    }
                break;
                case 0x50e0:case 0x05000://下
                    d='d';
                    if (y<h) {
                        ConPrintAt(x,y," ",1);
                        y++;
                        ConPrintAt(x,y,"O",1);
                    }
                break;
                case 0x4be0:case 0x04b00://左
                    d='l';
                    if (x>0) {
                        ConPrintAt(x,y," ",1);
                        x--;
                        ConPrintAt(x,y,"O",1);
                    }
                break;
                case 0x4de0:case 0x04d00://右
                    d='r';
                    if (x<w-1) {
                        ConPrintAt(x,y," ",1);
                        x++;
                        ConPrintAt(x,y,"O",1);
                    }
                break;
            }
//          cprintf("%04x pressed.\r\n",k);
        } else {
            switch (d) {
                case 'u':
                    if (y>0) {
                        ConPrintAt(x,y," ",1);
                        y--;
                        ConPrintAt(x,y,"O",1);
                    }
                break;
                case 'd':
                    if (y<h) {
                        ConPrintAt(x,y," ",1);
                        y++;
                        ConPrintAt(x,y,"O",1);
                    }
                break;
                case 'l':
                    if (x>0) {
                        ConPrintAt(x,y," ",1);
                        x--;
                        ConPrintAt(x,y,"O",1);
                    }
                break;
                case 'r':
                    if (x<w-1) {
                        ConPrintAt(x,y," ",1);
                        x++;
                        ConPrintAt(x,y,"O",1);
                    }
                break;
            }
        }
    }
    ClearConsole();
    ShowTheCursor();
    return 0;
}

[ooolinux]

总的来说，要考虑按键的时序和Sleep在主循环中的位置的关系。

[RWYQ阿伟]

我大概看了下，就结果而言，我还是不懂。
通过调试我发现不管两次按键时间多么接近，在循环的时候中间总是会出现一次按键识别不了，
比如我一打开就输入 左 下。
_getchar()
两次循环的值：75、80
可是实际上是：75、-32、80
中间多了一次是-32，然后多走了一步。
我简单修改了下RunGame()

void RunGame()
{
	while (1)
	{
		///////////////////////////////
		COORD pos_1 = { Wid + 2,4 };
		char a = 0;
		if (_kbhit())
		{
			a = _getch();
			if (a == -32)
			{
				continue;
			}

		}

		switch (a)
		{
		case 72:
			if (HeadPos.dir != 1)
			{
				HeadPos.dir = 0;//上
			}
			break;
		case 80:
			if (HeadPos.dir != 0)
			{
				HeadPos.dir = 1;//下
			}
			break;
		case 75:
			if (HeadPos.dir != 3)
			{
				HeadPos.dir = 2;//左
			}
			break;
		case 77:
			if (HeadPos.dir != 2)
			{
				HeadPos.dir = 3;//右
			}
			break;
		case 'a':
			pos_1.Y = 8;
			GetPosition(pos_1);
			system("pause");
			GetPosition(pos_1);
			printf("                ");
			GetPosition(pos_1);
			printf("按a键暂停游戏");
			break;
		case '5':
			speed = 50;
			GetPosition(pos_1);
			printf("当前模式：噩梦");
			break;
		case '4':
			speed = 100;
			GetPosition(pos_1);
			printf("当前模式：困难");
			break;
		case '3':
			speed = 150;
			GetPosition(pos_1);
			printf("当前模式：一般");
			break;
		case '2':
			speed = 200;
			GetPosition(pos_1);
			printf("当前模式：简单");
			break;
		case '1':
			speed = 1000;
			GetPosition(pos_1);
			printf("当前模式：蜗牛");
			break;
		}

		switch (HeadPos.dir)
		{
		case 0:
			HeadPos.pos.Y--;
			break;
		case 1:
			HeadPos.pos.Y++;
			break;
		case 2:
			HeadPos.pos.X -= 2;
			break;
		case 3:
			HeadPos.pos.X += 2;
			break;
		}
		///////////////////////////////
		
		if (GameOver())
		{
			break;
		}
		else if (HeadPos.pos.X == Food.X&&HeadPos.pos.Y == Food.Y)
		{
			AddSnakeBody(HeadPos.pos);
			InitFood();
		}
		else
		{
			MoveSnake(HeadPos.pos);
		}

		Sleep(speed);
	}
	COORD pos = { 0,Hei };
	GetPosition(pos);
	printf("很遗憾，你撞墙了或者自食自己，游戏结束!\n");
}

判断并把-32的值跳过，
然后效果差不多了。

我原以为是_kbhit()和_getch()这两个函数的特点，
可是我新建了一个项目，简单地搭建了类似的场景，测试结果却没有上面那种问题。
这个问题……搞不懂了。
我也是有点好奇，请路过的高手回答吧。

[赵4老师]

学习一下#3楼的代码。