书籍：C++ Primer Plus （第六版）（中文版）
工具：Dev-C++ 5.11
电脑信息：Intel® Xeon® CPU E5-2603 v3 @ 1.60GHz
系统类型：64位操作系统，基于X64的处理器 windows10 专业版
第13章 类继承
13.2 继承：is-a关系
13.3 多态公有继承
实例13.3
brass.h
cpp
#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 bal=0.0);
void Deposit(double amt);
virtual void withdraw(double amt);
double Balance() const;
virtual void ViewAcct() const;
virtual ~Brass(){}
};
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;}
void ResetRate(double r) {rate=r;}
void ResetOwes() {owesBank=0;}
};
#endifbrass.cpp
cpp
#include <iostream>
#include "brass.h"
using std::cout;
using std::endl;
using std::string;
typedef std::ios_base::fmtflags format;
typedef std::streamsize precis;
format setFormat();
void restore(format f,precis p);
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)
{
format initialState=setFormat();
precis prec=cout.precision(2);
if(amt<0)
cout<<"withdrawal amount must be positive; "
<<"withdrawal canceled.\n";
else if(amt<=balance)
balance -= amt;
else
cout<<"withdrawal amount of $"<<amt
<<" exceeds your balance.\n"
<<"withdrawal canceled.\n";
restore(initialState,prec);
}
double Brass::Balance() const
{
return balance;
}
void Brass::ViewAcct() const
{
format initialState=setFormat();
precis prec=cout.precision(2);
cout<<"Client: "<<fullName<<endl;
cout<<"Account Number: "<<acctNum<<endl;
cout<<"Balance:$"<<balance<<endl;
restore(initialState,prec);
}
BrassPlus::BrassPlus(const string &s,long an,double bal,
double m1,double r):Brass(s,an,bal)
{
maxLoan=m1;
owesBank=0.0;
rate=r;
}
BrassPlus::BrassPlus(const Brass &ba,double m1,double r):Brass(ba)
{
maxLoan=m1;
owesBank=0.0;
rate=r;
}
void BrassPlus::ViewAcct() const
{
format initialState=setFormat();
precis prec=cout.precision(2);
Brass::ViewAcct();
cout<<"maximum loan:$"<<maxLoan<<endl;
cout<<"Owed to bank:$"<<owesBank<<endl;
cout.precision(3);
cout<<"Loan rate: "<<100*rate<<"%\n";
restore(initialState,prec);
}
void BrassPlus::withdraw(double amt)
{
format initialState=setFormat();
precis prec=cout.precision(2);
double bal=Balance();
if(amt<bal)
Brass::withdraw(amt);
else if(amt<=bal+maxLoan-owesBank)
{
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);
}
else
cout<<"Credit limit exceeded. Transaction cancelled.\n";
restore(initialState,prec);
}
format setFormat()
{
return cout.setf(std::ios_base::fixed,std::ios_base::floatfield);
}
void restore(format f,precis p)
{
cout.setf(f,std::ios_base::floatfield);
cout.precision(p);
}usebrass1.cpp
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<<"withdrawing $4200 from the pigg Account:\n";
piggy.withdraw(4200.00);
cout<<"pigg account balance: $"<<piggy.Balance()<<endl;
cout<<"withdrawing $4200 from the Hoggy Account:\n";
Hoggy.withdraw(4200.00);
Hoggy.ViewAcct();
return 0;
}编译运行结果：
cpp
Client: Porcelot pigg
Account Number: 381299
Balance:$4000.00
Client: Horatio Hogg
Account Number: 382288
Balance:$3000.00
maximum loan:$500.00
Owed to bank:$0.00
Loan rate: 11.125%
Depositing $1000 into the Hogg Account:
New balance: $4000
withdrawing $4200 from the pigg Account:
withdrawal amount of $4200.00 exceeds your balance.
withdrawal canceled.
pigg account balance: $4000
withdrawing $4200 from the Hoggy Account:
Bank advance:$200.00
Finance charge:$22.25
Client: Horatio Hogg
Account Number: 382288
Balance:$0.00
maximum loan:$500.00
Owed to bank:$222.25
Loan rate: 11.125%
--------------------------------
Process exited after 0.2029 seconds with return value 0
请按任意键继续. . .使用虚方法特性
usebrass2.cpp
cpp
#include <iostream>
#include <string>
#include "brass.h"
const int CLIENTS = 4;
int main()
{
using std::cout;
using std::cin;
using std::endl;
Brass *p_clients[CLIENTS];
std::string temp;
long tempnum;
double tempbal;
char kind;
for(int i=0;i<CLIENTS;i++)
{
cout<<"Enter client's name: ";
getline(cin,temp);
cout<<"Enter client's account number: ";
cin>>tempnum;
cout<<"Enter opening balance: $";
cin>>tempbal;
cout<<"Enter 1 for Brass Accouont or "
<<"2 for Brassplus Account: ";
while(cin>>kind && (kind != '1' && kind !='2'))
cout<<"Enter either 1 or 2: ";
if(kind =='1')
p_clients[i] = new Brass(temp,tempnum,tempbal);
else
{
double tmax,trate;
cout<<" Enter the overdraft limit: $";
cin>>tmax;
cout<<"Enter the interest rate "
<<"as a decimal fraction: ";
cin>>trate;
p_clients[i]=new BrassPlus(temp,tempnum,tempbal,tmax,trate);
}
while(cin.get()!='\n')
continue;
}
cout<<endl;
for(int i=0;i<CLIENTS;i++)
{
p_clients[i]->ViewAcct();
cout<<endl;
}
for(int i=0;i<CLIENTS;i++)
{
delete p_clients[i];
}
cout<<"Done.\n";
return 0;
}编译运行结果：
cpp
Enter client's name: Harry Fishsong
Enter client's account number: 112233
Enter opening balance: $1500
Enter 1 for Brass Accouont or 2 for Brassplus Account: 1
Enter client's name: Dinah Otternoe
Enter client's account number: 121213
Enter opening balance: $1800
Enter 1 for Brass Accouont or 2 for Brassplus Account: 2
Enter the overdraft limit: $350
Enter the interest rate as a decimal fraction: 0.12
Enter client's name: Brenda Birdherd
Enter client's account number: 212118
Enter opening balance: $5200
Enter 1 for Brass Accouont or 2 for Brassplus Account: 2
Enter the overdraft limit: $800
Enter the interest rate as a decimal fraction: 0.10
Enter client's name: Tim Turtletop
Enter client's account number: 233255
Enter opening balance: $688
Enter 1 for Brass Accouont or 2 for Brassplus Account: 1
Client: Harry Fishsong
Account Number: 112233
Balance:$1500.00
Client: Dinah Otternoe
Account Number: 121213
Balance:$1800.00
maximum loan:$350.00
Owed to bank:$0.00
Loan rate: 12.000%
Client: Brenda Birdherd
Account Number: 212118
Balance:$5200.00
maximum loan:$800.00
Owed to bank:$0.00
Loan rate: 10.000%
Client: Tim Turtletop
Account Number: 233255
Balance:$688.00
Done.
--------------------------------
Process exited after 112.9 seconds with return value 0
请按任意键继续. . .