C#函数的简单使用

using System;
public class ATM
{
    public static string UserName = "";
    public static string UserPwd = "";
    public static double Money = 0;
    public static double Money1 = 0;
    public static void Main()
    {
        
        Menu();
    }
    //主菜单
    public static void Menu()
    {
        Console.WriteLine("----------请选择菜单-----------");
        Console.WriteLine("1,\t注册");
        Console.WriteLine("2,\t登录");
        Console.WriteLine("3,\t退出");
        string menu01 = Console.ReadLine();//得到的字符串类型
        if(menu01 == "1")
        {
            Register();//注册页面
        }
        if(menu01 == "2")
        {
            Login();
        }
    }
    //注册
    public static void Register()
    {
        Console.WriteLine("------------------------------------");
        Console.WriteLine("请选输入注册信息");
        Console.WriteLine("------------------------------------");
        Console.WriteLine("注册信息：请输入用户名");
        UserName = Console.ReadLine();
        if (UserName == "")
        {
            Console.WriteLine("用户名不能为空，注册失败");
            Menu();
        }
        Console.WriteLine("注册信息：请输入密码");
        UserPwd = Console.ReadLine();
        Console.WriteLine("请再次输入密码");
        string p = Console.ReadLine();
        if (UserPwd == "" || p == "")
        {
            Console.WriteLine("密码不能为空，注册失败");
            Register();
        }
        if (UserPwd != p)
        {
            Console.WriteLine("两次输入的密码不一致，注册失败");
            Register();
        }
        if(UserName != null && UserPwd == p)
        {
            Console.WriteLine("注册成功");
            Smenu();
        }
    }
    //登录
    public static void Login()
    {
        Console.WriteLine("------------------------------------");
        Console.WriteLine("------------------------------------");
        Console.WriteLine("请输入用户名");
        UserName = Console.ReadLine();
        Console.WriteLine("请输入密码");
        UserPwd = Console.ReadLine();
        if (UserName == ""|| UserPwd == "")
        {
            Console.WriteLine("用户名或密码不能为空，请重新登录！");
            Login();
        }else
        {
            Console.WriteLine("登录成功");
            Smenu();
        }
    }
    //登录成功菜单
    public static void Smenu()
    {
        Console.WriteLine("------------------------------------");
        Console.WriteLine("----------欢迎使用银行业务----------");
        Console.WriteLine("------------------------------------");
        Console.WriteLine("1,\t查询");
        Console.WriteLine("2,\t存款");
        Console.WriteLine("3,\t取款");
        Console.WriteLine("4,\t利息查询");
        Console.WriteLine("5,\t退出");
        string s = Console.ReadLine();
        if (s == "1")
        {
            Query();
        }
        if (s == "2")
        {
            Deposit();
        }
        if (s == "3")
        {
            TakeMoney();
        }
        if (s == "4")
        {
            Rate();
        }
    }
    //查询
    public static void Query()
    {
        Console.WriteLine("您的账户木有存款，请先存款！");
        Smenu();
    }
    //存款
    public static void Deposit()
    {
        Console.WriteLine("------------------------------------");
        Console.WriteLine("----------存款业务----------");
        Console.WriteLine("------------------------------------");
        Console.WriteLine("1,\t定期");
        Console.WriteLine("2,\t活期");
        Console.WriteLine("3,\t投资");
        Console.WriteLine("4,\t返回");
        string d = Console.ReadLine();
        if (d == "1")
        {
            DingQi();
        }
        if (d == "2")
        {
            HuoQi();
        }
        if (d == "3")
        {
            Ivest();
        }
        if (d == "4")
        {
            Smenu();
        }
    }
    //定期
    public static double DingQi()
    {
        Console.WriteLine("---------------------------------");
        Console.WriteLine("-----------定期存款--------------");
        Console.WriteLine("请输入存款期限,选择相应序号");
        Console.WriteLine("1,\t三个月");
        Console.WriteLine("2,\t六个月");
        Console.WriteLine("3,\t一年");
        Console.WriteLine("4,\t三年");
        Console.WriteLine("5,\t五年");
        string yeard = Console.ReadLine();
        Console.WriteLine("请输入存款数,只接收100元面值的钞票,一次最多准许放入5000元钞票！");
            Money1 = Convert.ToDouble(Console.ReadLine());
            int m = (int)Money1;
            if (m < 100)
            {
                Console.WriteLine("请取走现金！,您放入的现金少于100,请重新存款！");
                DingQi();
            }
            if (m > 5000)
            {
                Console.WriteLine("请取走现金！,您放入的现金大于5000,请重新存款！");
                DingQi();
            }
            if (yeard == "1")
            {
                Console.WriteLine("您本次定期存款是"+m+"元");
                Smenu();
            }
            if (yeard == "2")
            {
                Console.WriteLine("您本次定期存款是"+m+"元");
                Smenu();
            }
            if (yeard == "3")
            {
                Console.WriteLine("您本次定期存款是"+m+"元");
                Smenu();
            }
            if (yeard == "4")
            {
                Console.WriteLine("您本次定期存款是"+m+"元");
                Smenu();
            }
            if (yeard == "5")
            {
                Console.WriteLine("您本次定期存款是"+m+"元");
                Smenu();
            }
        Console.WriteLine("返回存款业务");
                Deposit();
                return (Money1);
    }
    //活期
    public static double HuoQi()
    {
        Console.WriteLine("---------------------------------");
        Console.WriteLine("-----------活期存款--------------");
        Console.WriteLine("1,\t进行活期存款");
        Console.WriteLine("2,\t返回存款业务");
        string h = Console.ReadLine();
        if (h == "1")
        {
            Console.WriteLine("请输入存款数,只接收100元面值的钞票");
            Money = Convert.ToDouble(Console.ReadLine());
            int m1 = (int)Money;
            if (m1 < 100 || m1 > 5000)
            {
                Console.WriteLine("请取走现金！,您放入的现金少于100或大于5000,请重新存款！");
                HuoQi();
            }else
            {
                Console.WriteLine("您本次活期存款是"+m1+"元");
                Deposit();
            }
        }
        if (h == "2")
        {
            Deposit();
        }
        return (Money);
    }
    //投资
    public static void Ivest()
    {
        Console.WriteLine("------------------------------------");
        Console.WriteLine("----------投资业务----------");
        Console.WriteLine("------------------------------------");
        Console.WriteLine("请选择投资年限");
        Console.WriteLine("1,\t一年");
        Console.WriteLine("2,\t三年");
        Console.WriteLine("3,\t五年");
        Console.WriteLine("4,\t十年");
        Console.WriteLine("5,\t返回主菜单");
        string i = Console.ReadLine();
        double iv = (Money+Money1);;
        if ((Money+Money1) < 100000)
        {
            Console.WriteLine("最低投资额为10万元，您的存款不足,请先存款！");
            Smenu();
        }
        if (i == "1")
        {
            double t1 = iv*0.05;
            Console.WriteLine("一年的投资利息为"+t1+"元");
            Console.WriteLine("您本次投资了"+iv+"元");
        }
        if (i == "2")
        {
            double t2 = iv*0.05*3;
            Console.WriteLine("三年的投资利息为"+t2+"元");
            Console.WriteLine("您本次投资了"+iv+"元");
        }
        if (i == "3")
        {
            double t3 = iv*0.05*5;
            Console.WriteLine("五年的投资利息为"+t3+"元");
            Console.WriteLine("您本次投资了"+iv+"元");
        }
        if (i == "4")
        {
            double t4 = iv*0.05*10;
            Console.WriteLine("十年的投资利息为"+t4+"元");
            Console.WriteLine("您本次投资了"+iv+"元");
        }
        if (i == "5")
        {
            Deposit();
        }
    }
    //取款
    public static void TakeMoney()
    {
        Console.WriteLine("------------------------------------");
        Console.WriteLine("----------取款业务----------");
        Console.WriteLine("------------------------------------");
        Console.WriteLine("请选择取款数额,每日最高可取2万元,定期取款请到柜台办理！");
        Console.WriteLine("1,\t100");
        Console.WriteLine("2,\t200");
        Console.WriteLine("3,\t500");
        Console.WriteLine("4,\t1000");
        Console.WriteLine("5,\t2000");
        Console.WriteLine("6,\t3000");
        Console.WriteLine("7,\t5000");
        Console.WriteLine("8,\t返回菜单");
        string t = Console.ReadLine();
        if (Money < 100.00)
        {
            Console.WriteLine("您的余额不足！");
        }
        if (t == "1")
        {
            if (Money > 100)
            {
                Console.WriteLine("您本次取款是100元");
                Money = Money-100;
                Smenu();
            }
        }
        if (t == "2")
        {
            if (Money > 200)
            {
                Console.WriteLine("您本次取款是200元");
                Money = Money-200;
                Smenu();
            }else
            {
                Console.WriteLine("您的余额不足！");
                Smenu();
            }
        }
        if (t == "3")
        {
            if (Money > 500)
            {
                Console.WriteLine("您本次取款是500元");
                Money = Money-500;
                Smenu();
            }else
            {
                Console.WriteLine("您的余额不足！");
                Smenu();
            }
        }
        if (t == "4")
        {
            if (Money > 1000)
            {
                Console.WriteLine("您本次取款是1000元");
                Money = Money-1000;
                Smenu();
            }else
            {
                Console.WriteLine("您的余额不足！");
                Smenu();
            }
        }
        if (t == "5")
        {
            if (Money > 2000)
            {
                Console.WriteLine("您本次取款是2000元");
                Money = Money-2000;
                Smenu();
            }else
            {
                Console.WriteLine("您的余额不足！");
                Smenu();
            }
        }
        if (t == "6")
        {
            if (Money > 3000)
            {
                Console.WriteLine("您本次取款是3000元");
                Money = Money-3000;
                Smenu();
            }else
            {
                Console.WriteLine("您的余额不足！");
                Smenu();
            }
        }
        if (t == "7")
        {
            if (Money > 5000)
            {
                Console.WriteLine("您本次取款是5000元");
                Money = Money-5000;
                Smenu();
            }else
            {
                Console.WriteLine("您的余额不足！");
                Smenu();
            }
        }
        if (t == "8")
        {
            Console.WriteLine("返回菜单");
            Smenu();    
        }
    }
    //利息查询
    public static void Rate()
    {
        Console.WriteLine("------------------------------------");
        Console.WriteLine("----------利息查询业务----------");
        Console.WriteLine("------------------------------------");
        Console.WriteLine("请选择存款年限");
        Console.WriteLine("1,\t三个月");
        Console.WriteLine("2,\t六个月");
        Console.WriteLine("3,\t一年");
        Console.WriteLine("4,\t三年");
        Console.WriteLine("5,\t五年");
        Console.WriteLine("6,\t返回存款业务");
        string r = Console.ReadLine();
        if (r == "1")
        {
            double l1 = Money1*0.0285/12*3;
            Console.WriteLine("三个月的利息为"+l1+"元");
            Smenu();
        }
        if (r == "2")
        {
            double l2 = Money1*0.0285/12*6;
            Console.WriteLine("六个月的利息为"+l2+"元");
            Smenu();
        }
        if (r == "3")
        {
            double l3 = Money1*0.0285;
            Console.WriteLine("一年的利息为"+l3+"元");
            Smenu();
        }
        if (r == "4")
        {
            double l4 = Money1*0.0285*3;
            Console.WriteLine("三年的利息为"+l4+"元");
            Smenu();
        }
        if (r == "5")
        {
            double l5 = Money1*0.0285*5;
            Console.WriteLine("五年的利息为"+l5+"元");
            Smenu();
        }
        if (r == "6")
        {
            Smenu();
        }
    }
}

这是函数调用的小练习，模仿ATM机。