账户类Account：
Id：账户号码
PassWord:账户密码
Name:真实姓名
PersonId:身份证号码
Email:客户的电子邮箱
Balance:账户余额

Deposit:存款方法，参数是double型的金额
Withdraw:取款方法，参数是double型的金额

银行的客户分为两种类型：
储蓄账户（SavingAccount）和信用账户（CreditAccount)
两者的区别是储蓄账户不许透支，而信用账户可以透支，并允许用户设置自己的透支额度（使用ceiling表示）

Bank类，
属性如下
（1）当前所有的账户对象的集合
（2）当前账户数量
构造方法
（1）用户开户：需要的参数包括id,密码，姓名，身份证号码，油箱和账户类型
（2）用户登录：参数包括id,密码，返回Account对象
（3）用户存款：参数包括id和存款数额
（4）用户取款：参数包括id和取款数额
（5）设置透支额度：参数包括id和新的额度，这个方法需要哦验证账户是否是信用账户参数
统计方法
（6）统计银行所有账户的余额总数
（7）统计所有信用账户透支额额度总数

源代码：

namespace ATM
{
abstract class Account
{
//账户号码
protected long id;
public long ID
{
get { return id; }
set { id = value; }
}
//账户密码
protected string password;
public string PassWord
{
get { return password; }
set { password = value; }
}
//户主的姓名
protected string name;
public string Name
{
get { return name; }
set { name = value; }
}
//身份证号码
protected string personId;
public string PersonId
{
get { return personId; }
set { personId = value; }
}
//email
protected string email;
public string Email
{
get { return email; }
set { email = value; }
}
//余额
protected double balance;
public double Balance
{
get { return balance; }
set { balance = value; }
}

//静态号码生成器
private static long idBuilder = 100000;
public static long IdBuilder
{
get { return idBuilder; }
set { idBuilder = value; }
}

public void Deposit(double sum)//存款
{
if (sum < 0)
throw new InvalidOperationException(\"输入的金额为负数\");
balance += sum;
}

public abstract void Withdraw(double sum);//取款
public Account()
{ }
public Account(string password, string name, string personId, string email)
{
this.id = ++idBuilder;
this.password = password;
this.name = name;
this.personId = personId;
this.email = email;
}
}
//创建CreditAccount类,该类继承抽象类Account
class CreditAccount : Account
{
protected double ceiling;//透支额度
public double Ceiling
{
get { return ceiling; }
set { ceiling = value; }
}
public CreditAccount(string password, string name, string personId, string email)
: base(password, name, personId, email)
{ }  
//信用账户的取款操作
public override void Withdraw(double sum)
{
if (sum < 0)
{
throw new InvalidOperationException(\"输入的金额为负数！\");
}
if (sum > balance + ceiling)
{
throw new InvalidOperationException(\"金额已经超出余额和透支度的总数了\");
}
balance -= sum;
}
}
//创建SavingAccount类,该类继承抽象类Account
class SavingAccount : Account
{
public SavingAccount(string password, string name, string personId, string email)
: base(password, name, personId, email)
{ }

public override void Withdraw(double sum)
{
if (sum < 0)
{
throw new InvalidOperationException(\"输入的金额为负数！\");
}
if(sum>balance)
{
throw new InvalidOperationException(\"金额已经超出金额！\");
}
balance -= sum;
}
}

//bank类，对银行中的所有账户进行管理
class Bank
{
//存放账户的集合
private List<Account> accounts;
public List<Account> Accounts
{
get { return accounts; }
set { accounts = value; }
}

//当前银行的账户数量
private int currentAccountNumber;
public int CurrentAccountNumber
{
get { return currentAccountNumber; }
set { currentAccountNumber = value; }
}

//构造函数
public Bank()
{
accounts=new List<Account>();
}

//开户
public Account OpenAccount(string password, string confirmationPassword, string name, string personId, string email, int typeOfAccount)
{
Account newAccount;
if (!password.Equals(confirmationPassword))
{
throw new InvalidOperationException(\"两次密码输入的不一致\");
}
switch (typeOfAccount)
{
case 1: newAccount = new SavingAccount(password, name, personId, email);
break;
case 2: newAccount = new CreditAccount(password,name,personId,email);
break;
default: throw new ArgumentOutOfRangeException(\"账户类型是1和2之间的整数\");
}
//把新开的账号加到集合中
accounts.Add(newAccount);
return newAccount;
}
//根据账户id得到账户对象
private Account GetAccountByID(long id)
{
foreach (Account account in accounts)
{
if (account.ID == id)
{
return account;
}
}
return null;
}

//根据账号和密码登陆账户
public Account SignIn(long id, string password)
{
foreach (Account account in accounts)
{
if (account.ID == id && account.PassWord.Equals(password))
{
return account;
}
}
throw new InvalidOperationException(\"用户名或者密码不正确，请重试\");
}

//存款
public Account Deposit(long id, double sum)
{
Account account = GetAccountByID(id);
if (account != null)
{
account.Deposit(sum);
return account;
}
throw new InvalidOperationException(\"非法账户！\");
}

//取款
public Account Withdraw(long id, double sum)
{
Account account = GetAccountByID(id);
if (account != null)
{
account.Withdraw(sum);
return account;
}
throw new InvalidOperationException(\"非法账户!\");
}

//设置透支额度
public Account SetCeiling(long id, double newCeiling)
{
Account account = GetAccountByID(id);
try
{
(account as CreditAccount).Ceiling = newCeiling;
return account;
}
catch (Exception)
{
throw new InvalidOperationException(\"次账户不是信用账户！\");
}
throw new InvalidOperationException(\"非法账户\");
}

//统计银行所有账户余额
public double GetTotalBalance()
{
double totalBalance = 0;
foreach (Account account in accounts)
{
totalBalance += account.Balance;
}
return totalBalance;
}
//统计所有信用账户透支额度总数
public double GetTotalCeiling()
{
double totalCeiling = 0;
foreach (Account account in accounts)
{
if (account is CreditAccount)
{
totalCeiling += (account as CreditAccount).Ceiling;
}
}
return totalCeiling;
}
}

//进行客户测试
class Program
{
static Account SignIn(Bank icbc)
{
Console.WriteLine(\"\\nPlease input your account ID\");
long id;
try
{
id = long.Parse(Console.ReadLine());
}
catch (FormatException)
{
Console.WriteLine(\"Invalid account ID!\");
return null;
}

Console.WriteLine(\"Please input your password\");
string password = Console.ReadLine();
Account account;
try
{
   account = icbc.SignIn(id, password);
}
catch (InvalidOperationException ex)
{
Console.WriteLine(ex.Message);
return null;
}
return account;
}
static void Main(string[] args)
{
Bank icbc = new Bank();
while (true)
{
Console.WriteLine(\"Please choose the service your need\");
Console.WriteLine(\"(1) Open a new account\");
Console.WriteLine(\"(2) Desposit\");
Console.WriteLine(\"(3) Withdraw\");
Console.WriteLine(\"(4) Set Ceiling\");
Console.WriteLine(\"(5) Get Total Balance\");
Console.WriteLine(\"(6) Get Total Ceiling\");
Console.WriteLine(\"(0) Exit\");
string choice;
choice = Console.ReadKey().KeyChar.ToString();
//ConsoleKey i=Console.ReadKey().Key;
switch (choice)
{
case \"1\":
{
string personId;
int typeOfAccount;
string password;
Console.WriteLine(\"\\nWhich kind of account do you want to open?\");
while (true)
{
Console.WriteLine(\"(1)Saving Account\\n(2)Credit Account\\n(3)return to Last Menu\");
try
{
typeOfAccount = int.Parse(Console.ReadLine());
}
catch (FormatException)
{
Console.WriteLine(\"\\nInvalid option,please choose again\");
continue;
}
if (typeOfAccount < 1 || typeOfAccount > 3)
{
Console.WriteLine(\"\\nInvalid option,please choooose again!\");
continue;
}
break;
}
if (typeOfAccount == 3)
{
break;
}
Console.WriteLine(\"\\nPlease input your name:\");
string name = Console.ReadLine();
while (true)
{
Console.WriteLine(\"Please input your Personal ID\");
personId = Console.ReadLine();
if (personId.Length != 18)
{
Console.WriteLine(\"Invalid Personal ID,please input again!\");
continue;
}
break;
}
Console.WriteLine(\"Please input your E-mail\");
string email = Console.ReadLine();
while (true)
{
Console.WriteLine(\"Please input your password\");
password = Console.ReadLine();
Console.WriteLine(\"Please confirm your password\");
if (password != Console.ReadLine())
{
Console.WriteLine(\"The password doesn\'t math!\");
continue;
}
break;
}
Account account = icbc.OpenAccount(password, password, name, personId, email, typeOfAccount);
Console.WriteLine(\"The account opened successfully\");
Console.WriteLine(\"Account ID:{0}\\nAccount Name;{1}\\nPerson ID:{2}\\nemail;{3}\\nBalance:{4}\",account.ID,account.Name,account.PersonId,account.Email,account.Balance);
}
break;
case \"2\":
{
Account account = SignIn(icbc);
if (account == null)
{
break;
}
int amount;
while (true)
{
Console.WriteLine(\"Please input the amount;\");
try
{
amount = int.Parse(Console.ReadLine());
}
catch (FormatException)
{
Console.WriteLine(\"Invalid input!\");
continue;
}
break;
}
try
{
icbc.Deposit(account.ID, amount);
}
catch (InvalidOperationException ex)
{
Console.WriteLine(ex.Message);
break;
}
Console.WriteLine(\"Deposit successfully,our balance is{0}元\",account.Balance);
}
break;
case \"3\":
{
Account account = SignIn(icbc);
if (account == null)
{
break;
}
int amount;
while (true)
{
Console.WriteLine(\"Please input the amount\");
try
{
amount = int.Parse(Console.ReadLine());
}
catch (FormatException)
{
Console.WriteLine(\"Invalid input!\");
continue;
}
break;
}
try
{
icbc.Withdraw(account.ID, amount);
}
catch (InvalidOperationException ex)
{
Console.WriteLine(ex.Message);
break;
}
Console.WriteLine(\"Deposit successfully,your balance is{0}yuan\",account.Balance);
}
break;
case \"4\":
{
Account account = SignIn(icbc);
if (account == null)
{
break;
}
double newCeiling;
while (true)
{
Console.WriteLine(\"Please input the new ceiling\");
try
{
newCeiling = double.Parse(Console.ReadLine());
}
catch (FormatException)
{
Console.WriteLine(\"Invalid input!\");
continue;
}
break;
}
try
{
icbc.SetCeiling(account.ID, newCeiling);
}
catch (InvalidOperationException ex)
{
Console.WriteLine(ex.Message);
break;
}
Console.WriteLine(\"Set ceiling successfully,your new ceiling is{0} yuan\",(account as CreditAccount).Ceiling);

}
break;
case \"5\":
Console.WriteLine(\"\\nThe total balance is:\"+icbc.GetTotalBalance());
break;
case \"6\":
Console.WriteLine(\"\\nThe total ceiling is:\" + icbc.GetTotalCeiling());
break;
case \"0\":
return;
default:
Console.WriteLine(\"\\nInvalid option,plwase choose again!\");
break;
}
}
}
}
}