#ifndef BRASS_H_
#define BRASS_H_

#include <string>

class Brass
{
private:
  std::string fullName;
  long acctNum;
  double balance;
public:
  Brass(const std::string& s = "Nullbody",long an = -1,double ba = 0.0);//default constructor
  void Deposit(double amt);
  double Balance() const;
  virtual void Withdraw(double amt);//virtual function
  virtual void ViewAcct() const;
  virtual ~Brass() {}//使用虛析構(gòu)函數(shù)確保先調(diào)用繼承類析構(gòu)函數(shù)
};

//brass plus account class
class BrassPlus:public Brass
{
private:
  double maxLoan;
  double rate;
  double owesBank;
public:
  BrassPlus(const std::string& s = "Nullbody",long an = -1,
        double bal = 0.0,double ml = 500,double r = 0.11125);
  BrassPlus(const Brass& ba,double ml = 500,double r = 0.11125);
  virtual void ViewAcct() const;
  virtual void Withdraw(double amt);
  void ResetMax(double m) {maxLoan = m;}//inline function
  void ResetRate(double r) {rate = r;}
  void ResetOwes() {owesBank = 0;}
};

#endif

brass.h

#include"brass.h"
#include <iostream>

using std::cout;
using std::endl;
using std::string;

//brass methods
Brass::Brass(const string& s,long an,double bal)
{
  fullName = s;
  acctNum = an;
  balance = bal;
}

void Brass::Deposit(double amt)
{
  if(amt < 0)
    cout << "Negative deposit not allowed;"
      << "deposit is cancelled.\n";
  else
    balance += amt;
}

void Brass::Withdraw(double amt)
{
  if(amt < 0)
    cout << "Withdrawal amount must be positive;"
      << "withdrawal canceled.\n";
  else if (amt <= balance)
    balance -= amt;
  else
    cout << "Withdrawal amount of $" << amt 
      << "exceeds your balance.\n"
      << "Withdrawal canceled.\n";
}

double Brass::Balance() const
{
  return balance;
}

void Brass::ViewAcct() const
{
  cout << "Client: " << fullName << endl;
  cout << "Account Number: " << acctNum << endl;
  cout << "Balance: $" << balance << endl;
}

//brassPlus methods
BrassPlus::BrassPlus(const string& s,long an,double bal,
           double ml,double r):Brass(s,an,bal)
{
  maxLoan = ml;
  owesBank = 0.0;
  rate = r;
}

BrassPlus::BrassPlus(const Brass& ba,double ml,double r):Brass(ba)
{
  maxLoan = ml;
  owesBank = 0.0;
  rate = r;
}

//redefine viewacct()
void BrassPlus::ViewAcct() const
{
  Brass::ViewAcct();
  cout << "Maximum loan: $" << maxLoan << endl;
  cout << "Owed to bank: $" << owesBank << endl;
}

void BrassPlus::Withdraw(double amt)
{
  double bal = Balance();
  if(amt <= bal)
    Brass::Withdraw(amt);
  else if(amt <= bal + maxLoan - owesBank)// 已欠 + 此欠 ≤ maxLoan
  {
    double advance = amt - bal;
    owesBank += advance * (1.0+rate);
    cout << "Bank advance: $" << advance << endl;
    cout << "Finance charge: $" << advance*rate << endl;
    Deposit(advance);
    Brass::Withdraw(amt);// return to zero
  }
  else
    cout << "Credit limit exceeded. Transcation cancelled.\n" ;
}

brass.cpp

#include <iostream>
#include "brass.h"

int main()
{
  using std::cout;
  using std::endl;

  Brass Piggy("Porcelot Pigg",381299,4000.00);
  BrassPlus Hoggy("Horatio Hogg",382288,3000.00);

  Piggy.ViewAcct();
  cout << endl;
  Hoggy.ViewAcct();
  cout << endl;
  
  cout << "Depositing $1000 into the Hogg Account:\n";
  Hoggy.Deposit(1000.00);
  cout << "New balance: $" <<Hoggy.Balance() <<endl;
  cout << endl;

  cout << "Withdrawing $4200 from the Pigg Account:\n";
  Piggy.Withdraw(4200.00);
  cout << "Pigg account balance: $" << Piggy.Balance() << endl;
  cout << endl;
  
  cout << "Withdrawing $4200 from the Hogg Account:\n";
  Hoggy.Withdraw(4200.00);
  Hoggy.ViewAcct();
  cout << endl;

  Brass dom("Dominic Banker",11224,4183.45);
  BrassPlus dot("Dorothy Banker",12118,2592.00);

  Brass& b1_ref = dom;
  Brass& b2_ref = dot;//use BrassPlus::ViewAcct() function

  b1_ref.ViewAcct();
  cout << endl;
  b2_ref.ViewAcct();
  cout << endl;

  return 0;
}

usebrass.cpp