c++ 贪吃蛇

贪吃蛇的程序，主框架是吉亮大神的，做了点修改，支持改变速度，改变地图大小；

/*NAME:SNAKE DATE:2014/1/11*/
#include <iostream.h>
#include <windows.h>
#include <stdlib.h>
#include <conio.h>
#include <time.h>  //使用当前时间做种子;
enum dir{up,down,left,right};  //枚举类型enum dir;

int map_lenth,map_wide;//地图的长和宽（即i和j）

//围墙;
class Fence
{
public:
    void InitFence();
    void OutputF();
public:
    char game[40][40];
}f; //定义对象;
//画框框;
void Fence::InitFence()
{
    for(int i=0; i<map_lenth; i++)
        for(int j=0; j<map_wide; j++)
        {
            if(i==0 || i==map_lenth-1 || j==0 || j==map_wide-1)
                game[i][j]= '*';
            else game[i][j]= ' ';
        }
}
//显示框框;
void Fence::OutputF()
{
    for(int i=0; i<map_lenth; i++)
    {
        for(int j=0; j<map_wide; j++)
            cout<<game[i][j]<<' ';
        cout<<endl;
    }
}

//蛇结点;
class SnakeNode
{
private:
    int x,y;
    SnakeNode *prior,*next;
public:
    void add_head(int x,int y);
    int get_x();
    int get_y();
    void delete_tail();
}*head=NULL,*tail=NULL;
//插入头结点;
void SnakeNode::add_head(int x,int y)
{
    SnakeNode *q=new SnakeNode;
    q->x =x; q->y =y;
    q->next =head;
    q->prior =NULL;
    if(head) head->prior =q;
    head =q;
    if(!tail) tail =head;
    f.game[x][y]= '~';  //f对象可以在定义Fence类时定义; 且Fence类在SnakeNode类前定义;
}
int SnakeNode::get_x()
{
    return x;
}
int SnakeNode::get_y()
{
    return y;
}
//删除尾结点;
void SnakeNode::delete_tail()
{
    SnakeNode *p=tail;
    f.game[tail->get_x()][tail->get_y()]= ' ';//把尾结点的坐标表示的'*'置为空格;
    if(tail==head)
        tail= head= NULL;
    else
    {
        tail= tail->prior;
        tail->next= NULL;
    }
    delete p;
}

//move移动;
class move
{
public:
    dir point;    //枚举变量point: 控制方向;
    int food_x;
    int food_y;
public:
    void moving();
    void change_point(char);  //改变方向;
    void get_food();
};

void move::moving()
{
    int a,b;
    a=head->get_x();  //取得头结点横坐标
    b=head->get_y();  //取得头结点纵坐标
    switch(point)
    {
        case up: --a; break;
        case down: ++a; break;
        case left: --b; break;
        case right: ++b; break;
    }
    if(a==map_lenth-1 || b==map_wide-1 || a==0 || b==0)
    {                //判断是否撞墙;                        
        cout<<"game over!!!"<<endl;
        exit(0);
    }
    if(a==food_x && b==food_y)
    {                    //吃food;
        head->add_head(a,b);
        get_food();
    }
    else{
        head->add_head(a,b); //插入头结点;
        head->delete_tail(); //删除尾结点;
    }
}

void move::change_point(char keydown)
{
    switch(keydown)
    {
        case 'w': 
        {
            if (point!=down)
            {
                point=up; break;
            }
            else break;
        }
        case 's': 
        {
            if (point!=up)
            {
                point=down; break;
            }
            else break;
        }
        case 'a': 
        {
            if (point!=right)
            {
                point=left; break;
            }
            else
                break;
        }
        case 'd': 
        {
            if (point!=left)
            {
                point=right; break;
            }
            else break;
        }
    }
}
void move::get_food()
{
    srand((unsigned int) time(NULL)); //做种子(程序运行时间); 
    food_x= rand()%(map_lenth-2)+1; 
    food_y= rand()%(map_wide-2)+1;
    f.game[food_x][food_y]='x';
}

//main();
int main()
{
    int speed;
    cout<<"Instruction: The snake's original length is 3.\nUsing 'w,s,a,d' to start the game and control the direction.\nGOOD LUCK!\n";
    cout<<"\nPlease put in 'lenth' & 'wide' to control the map and press enter to confirm.(limits:4~39)"<<endl;
    cout<<"Length=";
    cin>>map_lenth;
    cout<<"Wide=";
    cin>>map_wide;
    cout<<endl<<"Warning:the bigger num means the lower speed.Limits:1~500!\nSpeed=";
    cin>>speed;
    //画框框和小蛇;
    move m;
    f.InitFence();
    head->add_head(4,3);
    head->add_head(4,4);
    head->add_head(4,5);
    m.get_food();
    f.OutputF();
    while (true)
    {
        char keydown=getch(); //getch()返回键盘上读取的字符;包含头文件<conio.h>
        m.change_point(keydown);
        while(!kbhit())
        {                     //判断有没有按键落下;
            system("cls");  //清屏函数;
            m.moving();
            f.OutputF();
            Sleep(speed);
        }
    }
    return 0;
}