C++编程实践： 继承与多态

#pragma once
#ifndef BRASS_H_
#define	BRASS_H_
#include <string>
class Brass
{
private:
	std::string fullName;
	long accNum;
	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); //virtual function
	double Balance() const;
	virtual void ViewAcct() const; //virtual function
	virtual ~Brass() {};//virtual function
};
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 ReserOwes() { owesBank = 0; };
};
#endif

#include"brass.h"
#include<iostream>
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 std::string & s, long an, double bal) {
	fullName = s;
	accNum = 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 cancelled.\n";
	}
	else if (amt <= balance)
		balance -= amt;
	else
		cout << "Withdrawal amount of $" << amt
			 << " exceeds your balance.\n"
			 << "Withdrawal cancelled.\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: " << accNum << endl;
	cout << "Balance: $" << balance << endl;
	restore(initialState, prec);
}
BrassPlus::BrassPlus(const std::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;
}
void BrassPlus::ViewAcct() const {
	format initialState = setFormat();
	precis prec = cout.precision(2);
	Brass::ViewAcct();
	cout << "MaxLoan: $" << maxLoan << endl;
	cout << "Owed to Bank $" << owesBank << endl;
	cout.precision(3);
	cout << "Loan Rate: " << 100*rate <<"%"<< endl;
	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: $" << endl;
		cout << "Finance Charge: $" << advance*rate << endl;
		Deposit(advance);
		Brass::Withdraw(amt);
	}
	else
		cout << "Credit limit exceedsed, Transaction cancelled.\n";
	restore(initialState, prec);
}
format setFormat() {
	//set ###.## format
	return cout.setf(std::ios_base::fixed, std::ios_base::floatfield);
}
void restore(format f, precis p) {
	//reset the format and precision
	cout.setf(f, std::ios_base::floatfield);
	cout.precision(p);
}

#include<iostream>
#include"brass.h"
#include<string>
#pragma warning(disable:4996)
const int CLIENTS = 4;
int main(void) {
//	freopen("Text.txt", "r", stdin);
	using std::cin;
	using std::cout;
	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 Account 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 function: ";
			cin >> trate;
			p_clients[i] = new BrassPlus(temp, tempnum, tempbal, tmax, trate);
			
		}
		while (cin.get()!=‘\n‘)
		{
			continue;
		}
	}	
	for (int i = 0; i < CLIENTS; i++) {
		cout << endl; 
		p_clients[i]->ViewAcct();
	}
	for (int i = 0; i < CLIENTS; i++) {
		delete p_clients[i];
	}
	cout << "Done!!";
	return 0;
}