这个是用visual studio 和 C# 做的21点游戏的代码. 
帮我看看怎么能实现1. 电脑只随机得到1个1-40的数.(只有1个,而且用户不知道)
                  2. 用户只能得到1-10的数,但能得到几个(但如果大于20,就直接比较)
                  3. 点比较时,看谁的和20近或等于20,谁就赢.
//////////////////////////////////////////////////////////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 _21点
{
    public partial class Form1 : Form
    {
        public static int iswho=0;
        private int u1;
        private int u2;
        private int sum1;
        private int sum2;
        private int []pai1=new int[5];
        private int[] pai2 = new int[5];
        int kk;//记录是否已经平分了
        bool kaishi;        private int lost, win, pease;
        public Form1()
        {
            InitializeComponent();
            u1 = 0;
            u2 = 0;
            for (int i = 0; i < 5; i++)
            {
                pai1[i] = 0;
                pai2[i] = 0;
                
            }
            sum1 = 0;
            sum2 = 0;
            lost = 0;
            win = 0;
            pease = 0;
            kk = 0;
            kaishi = false;        }        private void Form1_Load(object sender, EventArgs e)
        {            this.textBox1.Text = "win:" + win + " lost:" + lost + " pease:" + pease;
        }        protected void get_radom()
        {
            Random a = new Random();
            for (int i = 0; i < 5; i++)
            {
               pai1[i] = a.Next(1, 14);
                pai2[i] = a.Next(1, 14);
               // pai2[i] = 2;
            }            this.lblu1.Text = pai1[0].ToString();
            this.lblu2.Text = pai1[1].ToString();
            this.lblu3.Text = pai1[2].ToString();
            this.lblu4.Text = pai1[3].ToString();
            this.lblu5.Text = pai1[4].ToString();
         
         
        }
        private void diannaoqushu()
        {            while (sum2 < 17)
            {
                sum2 = 0;
                u2++;
                for (int j = 0; j <= u2; j++)
                {
                    if (j == 5)
                        break;
                    sum2 += pai2[j];
                    
                }
                if (u2 == 4)
                    return;
            }            huhu();
        }
        private void button1_Click(object sender, EventArgs e)
        {
            kaishi = true;
            
            this.lblu2.Visible = false;
            this.lblu3.Visible = false;
            this.lblu4.Visible = false;
            this.lblu5.Visible = false;
           
            this.lbld2.Visible = false;
            this.lbld3.Visible = false;
            this.lbld4.Visible = false;
            this.lbld5.Visible = false;
            this.lbld1.Text = "";
            this.lbld2.Text = "";
            this.lbld3.Text = "";
            this.lbld4.Text = "";
            this.lbld5.Text = "";
            get_radom(); 
            u1 = 0;
            u2 = 0;
            this.lblu1.Visible = true;
            this.lbld1.Visible = true;
            sum1 = 0;
            sum2 = 0;
            kk=0;
            
        }        private void button2_Click(object sender, EventArgs e)
        {
            if (!kaishi)
            {
                MessageBox.Show("还没开始了!点击开始选牌吧!");
                return;
            }
            if (kk == 1)
            {
                MessageBox.Show("这局已经平分了,请重新开局吧!!!");
                return;
            }
            if (u1 == 4)
            {
                MessageBox.Show("5张都已选了,这么好的牌,还选,你傻啊!");
                return;
            }
            if (!isda())
                return;
            else
                u1++;
            sum1 = 0;
            for (int i = 0; i <= u1; i++)
            {                sum1 += pai1[i];
            }
            hehe();            if (sum2 < 17)
            {
                sum2 = 0;
                u2++;
                for (int j = 0; j <= u2; j++)
                    sum2 += pai2[j];
            }            huhu();
        }
        private void hehe()
        {
            if (u1 >=1)
            {
                this.lblu2.Visible = true;
                if(u1>=2)
                {
                    this.lblu3.Visible=true;
                    if(u1>=3)
                    {
                        this.lblu4.Visible=true;
                        if(u1>=4)
                        {
                            this.lblu5.Visible=true;
                        }
                        else return;
                    }
                }            }
            
        }
        private void huhu()
        {
            if (u2 >= 1)
            {
                this.lbld2.Visible = true;
                this.lbld2.Visible = true;
               
                if (u2 >= 2)
                {
                    this.lbld3.Visible = true;                    if (u2 >= 3)
                    {
                        this.lbld4.Visible = true;                        
                      
                        if (u2 >= 4)
                        {
                            this.lbld5.Visible = true;
                          
                        }
                        else return;
                    }
                }            }
        }        private void diaonaopai()
        {
            if (u2 >= 1)
            {
                this.lbld1.Text = pai2[0].ToString();
                this.lbld2.Text = pai2[1].ToString();
                if (u2 >= 2)
                {
                  
                    this.lbld3.Text = pai2[2].ToString();
                    if (u2 >= 3)
                    {
                       
                        this.lbld4.Text = pai2[3].ToString();                        if (u2 >= 4)
                        {
                           
                            this.lbld5.Text = pai2[4].ToString();
                        }
                        else return;
                    }
                }            }        }
        private bool isda()
        {
           
           
             if (sum1 > 21)
            {
                MessageBox.Show("不好意思!爆牌,你不能选牌了,开牌吧!!");
                return false;
            }
            else return true;        }
        private bool isxiao()
        {
            
            if (sum1 < 17)
            {
                MessageBox.Show("你的牌数还没到17哦!继续选牌吧,还有小心爆牌哦!!!");
                return false;
            }
            else return true;
        }
        private void button3_Click(object sender, EventArgs e)
        {
            if (!kaishi)
            {
                MessageBox.Show("还没开始了!点击开始选牌吧!");
                return;
            }
            if (kk == 1)
            {
                MessageBox.Show("这局平分已经平了,重新开局吧!");
                return;
            }
            if (!isxiao())
                return;
            diannaoqushu();
            diaonaopai();
            if ((u1 == 4)&&(sum1<=21))
            {
                
                if (u2 == 4)
                {
                    MessageBox.Show("运气不太好,这种牌都能和局!");
                    pease++;
                }
                else
                {
                    MessageBox.Show("你牌太好了,5张都没爆,翻3倍,win3局");
                    win += 3;
                }
                this.textBox1.Text = "win:" + win + " lost :" + lost + " pease:" + pease;
                kk = 1;
                return;
            }
            if ((u2 == 4)&&(sum2<=21))
            {
                huhu();
                MessageBox.Show("运气太次了,让电脑得了这种牌,你lost3局");
                lost += 3;
                this.textBox1.Text = "win:" + win + " lost :" + lost + " pease:" + pease;
                kk = 1;
                return;
            }
           
            
               // diannaoqushu();
             //   diaonaopai();
                if ((sum1 > 21 && sum2 > 21)||(sum1==sum2))
                {
                    MessageBox.Show("运气不错麽,和电脑打了平手! 你的总数"+sum1+"电脑总数"+sum2);
                    pease++;
                }
                else if ((sum1 > 21 && sum2<=21))
                {
                    MessageBox.Show("你运气太次了,输给电脑了! 你的总数" + sum1 + "电脑总数" + sum2);
                    lost++;                }
                    
                else if ((sum1 > sum2)||((sum1<=21)&&(sum2>21)))
                {
                    MessageBox.Show("恭喜你,you win 你的总数"+sum1+"电脑总数"+sum2);
                    win++;                }
                else
                {
                    MessageBox.Show("你运气太次了,输给电脑了! 你的总数" + sum1 + "电脑总数" + sum2);
                    lost++;
                }
                kk = 1;
            
                this.textBox1.Text = "win:" + win + " lost :" + lost + " pease:" + pease;
           }        private void toolStripButton2_Click(object sender, EventArgs e)
        {
            Frmhelp_usr fm = new Frmhelp_usr();
            fm.Text = "游戏简介";
            iswho = 0;
            fm.Show();
        }        private void toolStripButton3_Click(object sender, EventArgs e)
        {
            Frmhelp_usr fms = new Frmhelp_usr();
            fms.Text = "作者简介!";
            iswho = 1;
            fms.Show();
        }        private void textBox1_TextChanged(object sender, EventArgs e)
        {        }        private void label4_Click(object sender, EventArgs e)
        {        }        private void lblu1_Click(object sender, EventArgs e)
        {        }
    }
    
}