Mybank

 using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Text;
 using System.Threading.Tasks;

 namespace MyBank
 {
     class Bank
     {
         Card[] twos = new Card[];
        public void fx()
        {
            //第一张卡
            Card t1 = new Card();
            t1.kahao = "";
            t1.mima = "";
            t1.names = "小明";
            t1.yumoney = ;
            //第二张卡
            Card t2 = new Card();
            t2.kahao = "";
            t2.mima = "";
            t2.names = "小词";
            t2.yumoney = ;

            twos[] = t1;
            twos[] = t2;
        }
        public void Show()

        {
            for (int i = ; i < twos.Length; i++)
            {
                if (twos[i] != null)
                {
                    Console.WriteLine("持卡人:{0}\t余额:{1}", twos[i].names, twos[i].yumoney);
                }
            }
            Console.WriteLine("=====================================================");
        }

       //欢迎界面
        public void huanying()
        {
            bool flag = true;
            while (flag)
            {
                Console.WriteLine("\n欢迎进入\t某某某‘s \t的ATM系统\n");
                Console.WriteLine("请选择功能模块，按照以下操作↓");
                Console.WriteLine("===============================欢迎使用自动银行服务============================= ");
                Console.WriteLine("1:开户\t 2:存款\t 3:取款\t 4:查询余额\t 5:转账\t  6:修改密码\t 7:退出");
                Console.WriteLine("================================================================================ ");
                string choice = Console.ReadLine();
                switch (choice)
                {
                    case "":
                        //开户
                        kaihu();
                        break;
                    case "":
                        //存款
                        MoneyIn();
                        break;
                    case "":
                        //取款
                       MoneyOut();
                        break;
                    case "":
                        //查询余额
                        chaxunMoney();
                        break;
                    case "":
                        //转账
                        TransferMoney();
                        break;
                    case "":
                        //修改密码
                        ModifyPwd();
                        break;
                    case"":
                        //退出
                        Console.WriteLine("欢迎使用");
                        break;
                    default:
                        Console.WriteLine("您输入的有误,请从新输入！");
                        Console.WriteLine("");
                        break;
                }
                Console.ReadLine();
            }

        }
        //开户
        public void kaihu()
        {
            Console.WriteLine("这里是开户功能");
            Console.WriteLine("请输入账号：");
            string zh = Console.ReadLine();
            foreach (Card item in twos)
            {
                if (item.kahao.Equals(zh))
                {
                    Console.WriteLine("已有账号,请从新输入：");
                    zh = Console.ReadLine();
                }
                Console.WriteLine("请输入密码：");
                string kaPwd = Console.ReadLine();
                Console.WriteLine("请输入预存款金额：");
                double money = double.Parse(Console.ReadLine());
                Card two = new Card();
                two.kahao = zh;
                two.mima = kaPwd;
                two.yumoney = money;
                for (int i = ; i < twos.Length; i++)
                {
                    if (twos[i] == null)
                    {
                        twos[i] = two;
                        Console.WriteLine("恭喜您,开户成功,您的卡号是{0}", zh);
                        break;
                    }
                }
                break;
            }
            Console.WriteLine("\n是否返回主页面？(y/n)");
           char  num=char.Parse(Console.ReadLine());
            switch (num)
            {
                case 'y':
                    huanying();
                    break;
                case 'n':
                    Console.WriteLine("欢迎下次光临");

                    break;
            }
            }

        //存款
        public void MoneyIn()
        {
            Console.WriteLine("欢迎进入存款区");
            Console.WriteLine("请输入账号");
            string zh2 = Console.ReadLine();
            bool flag = false;
            foreach (Card item in twos)
            {
                if (item != null)
                {
                    if (item.kahao.Equals(zh2))
                    {
                        flag = true;
                        Console.WriteLine("请输入存款金额");
                        double money = double.Parse(Console.ReadLine());
                        item.yumoney += money;
                        Console.WriteLine("存款成功,当前余额为:{0}", item.yumoney);

                        break;
                    }
                }
            }
            if (flag == false)
            {
                Console.WriteLine("卡号不存在");
            }
            Console.WriteLine("\n是否返回主页面？(y/n)");
            char num = char.Parse(Console.ReadLine());
            switch (num)
            {
                case 'y':
                    huanying();
                    break;
                case 'n':
                    Console.WriteLine("欢迎下次光临！凸^-^凸");

                    break;
            }
        }
        //取款
        public void MoneyOut()
        {
            Console.WriteLine("请输入账号");
            string account = Console.ReadLine();
            bool kh = false;
            foreach (Card item in twos)
            {
                if (item != null)
                {
                    if (item.kahao.Equals(account))
                    {
                        kh = true;
                        Console.WriteLine("请输入密码");
                        string pwd2 = Console.ReadLine();
                        if (item.mima.Equals(pwd2))
                        {
                            Console.WriteLine("请输入取款金额");
                            double money = double.Parse(Console.ReadLine());
                            while (money > item.yumoney)
                            {
                                Console.WriteLine("余额不足，请重新输入取款金额");
                                money = double.Parse(Console.ReadLine());
                            }
                            item.yumoney -= money;
                            Console.WriteLine("取款成功");
                            Console.WriteLine("当前卡内余额{0}", item.yumoney);
                            break;

                        }
                        else
                        {
                            Console.WriteLine("密码错误");
                        }
                    }
                }
            }
            if (kh == false)
            {
                Console.WriteLine("没有该卡号");
            }
            Console.WriteLine("\n是否返回主页面？(y/n)");
           char  num=char.Parse(Console.ReadLine());
            switch (num)
            {
                case 'y':
                    huanying();
                    break;
                case 'n':
                    Console.WriteLine("欢迎下次光临！");

                    break;
            }
        }
        //查询余额
        public void chaxunMoney()
        {
            bool flag = false;
            Console.WriteLine("请输入卡号");
            string account = Console.ReadLine();
            Console.WriteLine("请输入密码");
            string pwd = Console.ReadLine();
            foreach (Card item in twos)
            {
                if (item!=null)
                {
                    if (item.kahao.Equals(account) && item.mima.Equals(pwd))
                    {
                        flag=true;
                        Console.WriteLine("用户名是{0}的账户余额是{1}", item.names, item.yumoney);
                        break;
                    }
                }
            }
                     if (flag==false)
                            {
                                 Console.WriteLine("账号有误,请从新输入");
                           }
             Console.WriteLine("\n是否返回主页面？(y/n)");
           char  num=char.Parse(Console.ReadLine());
            switch (num)
            {
                case 'y':
                    huanying();
                    break;
                case 'n':
                    Console.WriteLine("欢迎下次光临！");

                    break;
            }
        }

        //转账
        public void TransferMoney()
        {
            Console.WriteLine("请输入转出卡卡号");
            string zc = Console.ReadLine();
            bool fromIsOrNot = false;
            bool toIsOrNot = false;
             foreach (Card item in twos)
            {
                if (item!=null&&item.kahao.Equals(zc))
                {
                    fromIsOrNot = true;

            Console.WriteLine("请输入转出卡卡密码");
            string pwdFrom = Console.ReadLine();
                    if (item.mima.Equals(pwdFrom))
                    {
                    Console.WriteLine("请输入转入卡卡号");
                   string zr = Console.ReadLine();
                        foreach (Card toItem in twos)
                        {
                            if (toItem!=null&&toItem.kahao.Equals(zr))
                            {
                                toIsOrNot = true;
                                Console.WriteLine("请输入转账金额");
                                double money = double.Parse(Console.ReadLine());
                                while (money > item.yumoney)
                                {
                                    Console.WriteLine("转账金额不够，请重新输入");
                                    money = double.Parse(Console.ReadLine());
                                }
                                item.yumoney -= money;
                                toItem.yumoney += money;
                                Console.WriteLine("转账成功，您的余额为{0}",item.yumoney);
                                break;
                            }

                        }
                        if (toIsOrNot==false)
                        {
                            Console.WriteLine("转入卡不存在");
                        }
                        break;
                    }
                    else
                    {
                        Console.WriteLine("转出卡密码错误");
                    }
                }
            }
            if (fromIsOrNot==false)
            {
                Console.WriteLine("转出卡不存在！");
            }
             Console.WriteLine("\n是否返回主页面？(y/n)");
           char  num=char.Parse(Console.ReadLine());
            switch (num)
            {
                case 'y':
                    huanying();
                    break;
                case 'n':
                    Console.WriteLine("欢迎下次光临");

                    break;
            }
        }

        //修改密码
        public string xinmima;
        public void ModifyPwd()
        {
                Console.WriteLine("请输入账号:");
                string no = Console.ReadLine();

                for (int i = ; i < twos.Length; i++)
                {
                    if (twos[i] != null)
                    {
                        if (twos[i].kahao == no)
                        {
                            Console.WriteLine("请输入原密码:");
                            string mima1 = Console.ReadLine();
                            for (int j = ; j < ; j++)
                            {
                                if (twos[i].mima == mima1)
                                {
                                    Console.WriteLine("请输入新密码:");
                                    xinmima = Console.ReadLine();
                                    Console.WriteLine("请再次输入新密码:");
                                    if (xinmima == Console.ReadLine())
                                    {
                                        twos[i].mima = xinmima;
                                        Console.WriteLine("账户密码修改成功!!");
                                        break;
                                    }

                                }
                            }

                             break;
                        }
                    }
                    if (twos[i].kahao != no)
                    {

                        Console.WriteLine("您输入的账号不存在!");
                        break;

                    }
                }
             Console.WriteLine("\n是否返回主页面？(y/n)");
           char  num=char.Parse(Console.ReadLine());
            switch (num)
            {
                case 'y':
                    huanying();
                    break;
                case 'n':
                    Console.WriteLine("欢迎下次光临");
                    break;
            }

        }

        }
     }

Card

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace MyBank
{
    class Card
    {
        //卡号
        public string kahao;
        //密码
        public string mima;
        //持卡人
        public string names;
        //余额
        public double yumoney;
    }
}

Main()

 namespace MyBank
 {
     class Program
     {
         static void Main(string[] args)
         {
             Bank bank = new Bank();

             bank.fx();//卡信息
             bank.Show();//展示卡信息
             bank.huanying();//欢迎界面
             Console.ReadLine();
         }
     }
 }