winform 贪吃蛇游戏，蛇总是一直线运动，无法转弯

Question

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;namespace snake
{
    public partial class Form1 : Form
    {
        //1:上  2:下  3.左  4.右
        private int direction = 1;        //新建picturebox数组
        private PictureBox[] pb = new PictureBox[50];
        //蛇的结点数
        private int i=0;
        //蛇的身体结点
        private string picPath = Application.StartupPath + "\\snake.jpg";
        public Form1()
        {
            InitializeComponent();
        }        private void Form1_Load(object sender, EventArgs e)
        {
            //timer1控制蛇的运动，timer2控制食物出现间隔
            timer1.Enabled = true;
            timer2.Enabled = true;
            pictureBox2.Visible = false;
            //初始将蛇头放入picturebox数组中
            pb[0] = pictureBox1;
 
        }        private void timer1_Tick(object sender, EventArgs e)
        {
            //根据不同方向控制蛇运动
            if (this.direction == 1)
            {
                pb[0].Top = pb[0].Top - 5;
            }
            if (this.direction == 2)
            {
                pb[0].Top = pb[0].Top + 5;
            }
            if (this.direction == 3)
            {
                pb[0].Left = pb[0].Left - 5;
            }
            if (this.direction == 4)
            {
                pb[0].Left = pb[0].Left + 5;
            }
            //循环设置蛇的身体位置
            for (int j = 1; j <= i; j++)
            {
                if (this.direction == 1)
                {
                    pb[j].Top = pb[j - 1].Top + 17;
                    pb[j].Left = pb[j - 1].Left;                }
                if (this.direction == 2)
                {
                    pb[j].Top = pb[j - 1].Top - 17;
                    pb[j].Left = pb[j - 1].Left;
                }
                if (this.direction == 3)
                {
                    pb[j].Top = pb[j - 1].Top;
                    pb[j].Left = pb[j - 1].Left + 17;
                }
                if (this.direction == 4)
                {
                    pb[j].Top = pb[j - 1].Top;
                    pb[j].Left = pb[j - 1].Left - 17;
                }
                
            }
            //如果蛇头与食物距离坐标在范围5之内，算吃到食物
            if (Math.Abs(pictureBox1.Top - pictureBox2.Top) <= 5 && Math.Abs(pictureBox1.Left - pictureBox2.Left) <= 5)
            {
                //蛇的结点数+1
                this.i++;
                //随机生成食物
                rand_loc();
                pictureBox2.Visible = false;
                timer2.Enabled = true;
                //新生成一结点
                pb[i] = new PictureBox();
                pb[i].Image = Image.FromFile(this.picPath);
                pb[i].Size = new Size(16, 16);
                //增加结点到窗体
                this.Controls.Add(pb[i]);
                
            }
            //是否撞墙
            if (pb[0].Top < 0 || pb[0].Top > this.Height-50 || pb[0].Left < 0 || pb[0].Left > this.Width-25)
            {
                timer1.Enabled = false;
                timer2.Enabled = false;
                if (MessageBox.Show("你输了!是否重玩?", "game over!", MessageBoxButtons.YesNo) == DialogResult.Yes)
                {
                    this.Hide();
                    Form1 f1 = new Form1();
                    f1.Show();
                }
                else
                {
                    Application.Exit();
                }
            }
       
}        private void Form1_KeyDown(object sender, KeyEventArgs e)
        {
            if (e.KeyCode == Keys.Up)
            {
                this.direction = 1;
            }
            if (e.KeyCode == Keys.Down)
            {
                this.direction = 2;
            }
            if (e.KeyCode == Keys.Left)
            {
                this.direction = 3;
            }
            if (e.KeyCode == Keys.Right)
            {
                this.direction = 4;
            }            
        }
        //随机生成食物位置
        public void rand_loc()
        {
            Random r = new Random();
            int x = r.Next(30, this.Width - 30);
            int y = r.Next(30, this.Height - 50);
            pictureBox2.Location = new Point(x, y);
        }
        private void timer2_Tick(object sender, EventArgs e)
        {
            rand_loc();
            pictureBox2.Visible = true;
            timer2.Enabled = false;
        }
    }
}
现在效果是蛇只能一直线，如何让蛇扭动起来，如果在timer1.tick()中设置循环pb[j].location=pb[j-1].location，这样，蛇的身体都会与蛇头重合，应该怎么改呢...

Answer 1

[大致是：code=C#]
             for (int j = 1; j < pb.length; j++)
               pb[j] = pb[j - 1];
            pb[0]=
            if (this.direction == 1)
            {
                pb[0].Top = pb[0].Top - 5;
            }
            else if (this.direction == 2)
            {
                pb[0].Top = pb[0].Top + 5;
            }
            else if (this.direction == 3)
            {
                pb[0].Left = pb[0].Left - 5;
            }
            else if (this.direction == 4)
            {
                pb[0].Left = pb[0].Left + 5;
            }
[/code]

Answer 2

大致是
  for (int j = 1; j < pb.length; j++)
  {
         pb[j].Top = pb[j - 1].Top;
         pb[j].Left = pb[j - 1].Left;
  }
  if (this.direction == 1)
  {
    pb[0].Top = pb[0].Top - 5;
  }
  else if (this.direction == 2)
  {
    pb[0].Top = pb[0].Top + 5;
  }
  else if (this.direction == 3)
  {
    pb[0].Left = pb[0].Left - 5;
  }
  else if (this.direction == 4)
  {
    pb[0].Left = pb[0].Left + 5;
  }

Answer 3

晕！本来是既要调整代码次序又要要修改循环次序的，竟然美鞋后一个  for (int j = pb.length; j >0 ; j--)
  {
         pb[j].Top = pb[j - 1].Top;
         pb[j].Left = pb[j - 1].Left;
  }
  if (this.direction == 1)
  {
    pb[0].Top = pb[0].Top - 5;
  }
  else if (this.direction == 2)
  {
    pb[0].Top = pb[0].Top + 5;
  }
  else if (this.direction == 3)
  {
    pb[0].Left = pb[0].Left - 5;
  }
  else if (this.direction == 4)
  {
    pb[0].Left = pb[0].Left + 5;
  }

Answer 4

Form1_KeyDown方法需要订阅Form1类实例的KeyDown事件，或者重写Form1类的OnDeyDown方法

Answer 5

for (int j = pb.length-1; j >0 ; j--)
   ......
然后再处理pb[0]
一定要从最后一个开始向前修改起，而不能倒过来。