【C++脑图系列09】泛型程序设计与STL

脑图

代码

//date.h
#ifndef __DATE_H__
#define __DATE_H__

class Date {	//日期类
private:
	int year;		//年
	int month;		//月
	int day;		//日
	int totalDays;	//该日期是从公元元年1月1日开始的第几天

public:
	Date(int year = 1, int month = 1, int day = 1);	//用年、月、日构造日期
	static Date read();
	int getYear() const { return year; }
	int getMonth() const { return month; }
	int getDay() const { return day; }
	int getMaxDay() const;		//获得当月有多少天
	bool isLeapYear() const {	//判断当年是否为闰年
		return year % 4 == 0 && year % 100 != 0 || year % 400 == 0;
	}
	void show() const;			//输出当前日期
	//计算两个日期之间差多少天	
	int operator - (const Date& date) const {
		return totalDays - date.totalDays;
	}
	//判断两个日期的前后顺序
	bool operator < (const Date& date) const {
		return totalDays < date.totalDays;
	}
};

#endif //__DATE_H__

//date.cpp
#include "date.h"
#include <iostream>
#include <cstdlib>
using namespace std;

namespace {	//namespace使下面的定义只在当前文件中有效
	//存储平年中某个月1日之前有多少天，为便于getMaxDay函数的实现，该数组多出一项
	const int DAYS_BEFORE_MONTH[] = { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365 };
}

Date::Date(int year, int month, int day) : year(year), month(month), day(day) {
	if (day <= 0 || day > getMaxDay()) {
		cout << "Invalid date: ";
		show();
		cout << endl;
		exit(1);
	}
	int years = year - 1;
	totalDays = years * 365 + years / 4 - years / 100 + years / 400
		+ DAYS_BEFORE_MONTH[month - 1] + day;
	if (isLeapYear() && month > 2) totalDays++;
}

Date Date::read() {
	int year, month, day;
	char c1, c2;
	cin >> year >> c1 >> month >> c2 >> day;
	return Date(year, month, day);
}

int Date::getMaxDay() const {
	if (isLeapYear() && month == 2)
		return 29;
	else
		return DAYS_BEFORE_MONTH[month]- DAYS_BEFORE_MONTH[month - 1];
}

void Date::show() const {
	cout << getYear() << "-" << getMonth() << "-" << getDay();
}

//accumulator.h
#ifndef __ACCUMULATOR_H__
#define __ACCUMULATOR_H__
#include "date.h"

class Accumulator {	//将某个数值按日累加
private:
	Date lastDate;	//上次变更数值的时期
	double value;	//数值的当前值
	double sum;		//数值按日累加之和
public:
	//构造函数，date为开始累加的日期，value为初始值
	Accumulator(const Date &date, double value)
		: lastDate(date), value(value), sum(0) { }

	//获得到日期date的累加结果
	double getSum(const Date &date) const {
		return sum + value * (date - lastDate);
	}

	//在date将数值变更为value
	void change(const Date &date, double value) {
		sum = getSum(date);
		lastDate = date;
		this->value = value;
	}

	//初始化，将日期变为date，数值变为value，累加器清零
	void reset(const Date &date, double value) {
		lastDate = date;
		this->value = value;
		sum = 0;
	}
};

#endif //__ACCUMULATOR_H__

//account.h
#ifndef __ACCOUNT_H__
#define __ACCOUNT_H__
#include "date.h"
#include "accumulator.h"
#include <string>
#include <map>

class Account;	//前置声明

class AccountRecord {	//账目记录
private:
	Date date;				//日期
	const Account *account;	//账户
	double amount;			//金额
	double balance;			//余额
	std::string desc;		//描述
public:
	//构造函数
	AccountRecord(const Date &date, const Account *account, double amount, double balance, const std::string& desc);
	void show() const;	//输出当前记录
};

//定义用来存储账目记录的多重映射类型
typedef std::multimap<Date, AccountRecord> RecordMap;

class Account { //账户类
private:
	std::string id;	//帐号
	double balance;	//余额
	static double total; //所有账户的总金额
	static RecordMap recordMap;	//账目记录
protected:
	//供派生类调用的构造函数，id为账户
	Account(const Date &date, const std::string &id);
	//记录一笔帐，date为日期，amount为金额，desc为说明
	void record(const Date &date, double amount, const std::string &desc);
	//报告错误信息
	void error(const std::string &msg) const;
public:
	const std::string &getId() const { return id; }
	double getBalance() const { return balance; }
	static double getTotal() { return total; }
	//存入现金，date为日期，amount为金额，desc为款项说明
	virtual void deposit(const Date &date, double amount, const std::string &desc) = 0;
	//取出现金，date为日期，amount为金额，desc为款项说明
	virtual void withdraw(const Date &date, double amount, const std::string &desc) = 0;
	//结算（计算利息、年费等），每月结算一次，date为结算日期
	virtual void settle(const Date &date) = 0;
	//显示账户信息
	virtual void show() const;
	//查询指定时间内
	static void query(const Date& begin, const Date& end);
};

class SavingsAccount : public Account { //储蓄账户类
private:
	Accumulator acc;	//辅助计算利息的累加器
	double rate;		//存款的年利率
public:
	//构造函数
	SavingsAccount(const Date &date, const std::string &id, double rate);
	double getRate() const { return rate; }
	virtual void deposit(const Date &date, double amount, const std::string &desc);
	virtual void withdraw(const Date &date, double amount, const std::string &desc);
	virtual void settle(const Date &date);
};

class CreditAccount : public Account { //信用账户类
private:
	Accumulator acc;	//辅助计算利息的累加器
	double credit;		//信用额度
	double rate;		//欠款的日利率
	double fee;			//信用卡年费

	double getDebt() const {	//获得欠款额
		double balance = getBalance();
		return (balance < 0 ? balance : 0);
	}
public:
	//构造函数
	CreditAccount(const Date &date, const std::string &id, double credit, double rate, double fee);
	double getCredit() const { return credit; }
	double getRate() const { return rate; }
	double getFee() const { return fee; }
	double getAvailableCredit() const {	//获得可用信用
		if (getBalance() < 0) 
			return credit + getBalance();
		else
			return credit;
	}
	virtual void deposit(const Date &date, double amount, const std::string &desc);
	virtual void withdraw(const Date &date, double amount, const std::string &desc);
	virtual void settle(const Date &date);
	virtual void show() const;
};

#endif //__ACCOUNT_H__

//account.cpp
#include "account.h"
#include <cmath>
#include <iostream>
#include <utility>
using namespace std;
using namespace std::rel_ops;

//AccountRecord类的实现
AccountRecord::AccountRecord(const Date &date, const Account *account, double amount, double balance, const std::string& desc)
	: date(date), account(account), amount(amount), balance(balance), desc(desc) { }

void AccountRecord::show() const {
	date.show();
	cout << "\t#" << account->getId() << "\t" << amount << "\t" << balance << "\t" << desc << endl;
}

//Account类的实现
double Account::total = 0;
RecordMap Account::recordMap;
Account::Account(const Date &date, const string &id)
	: id(id), balance(0) {
	date.show();
	cout << "\t#" << id << " created" << endl;
}

void Account::record(const Date &date, double amount, const string &desc) {
	amount = floor(amount * 100 + 0.5) / 100;	//保留小数点后两位
	balance += amount;
	total += amount;
	AccountRecord record(date, this, amount, balance, desc);
	recordMap.insert(make_pair(date, record));
	record.show();
}

void Account::show() const {
	cout << id << "\tBalance: " << balance;
}

void Account::error(const string &msg) const {
	cout << "Error(#" << id << "): " << msg << endl;
}

void Account::query(const Date& begin, const Date& end) {
	if (begin <= end) {
		RecordMap::iterator iter1 = recordMap.lower_bound(begin);
		RecordMap::iterator iter2 = recordMap.upper_bound(end);
		for (RecordMap::iterator iter = iter1; iter != iter2; ++iter)
			iter->second.show();
	}
}

//SavingsAccount类相关成员函数的实现
SavingsAccount::SavingsAccount(const Date &date, const string &id, double rate)
	: Account(date, id), rate(rate), acc(date, 0) { }

void SavingsAccount::deposit(const Date &date, double amount, const string &desc) {
	record(date, amount, desc);
	acc.change(date, getBalance());
}

void SavingsAccount::withdraw(const Date &date, double amount, const string &desc) {
	if (amount > getBalance()) {
		error("not enough money");
	} else {
		record(date, -amount, desc);
		acc.change(date, getBalance());
	}
}

void SavingsAccount::settle(const Date &date) {
	if (date.getMonth() == 1) {	//每年的一月计算一次利息
		double interest = acc.getSum(date) * rate
			/ (date - Date(date.getYear() - 1, 1, 1));
		if (interest != 0)
			record(date, interest, " interest");
		acc.reset(date, getBalance());
	}
}

//CreditAccount类相关成员函数的实现
CreditAccount::CreditAccount(const Date& date, const string& id, double credit, double rate, double fee)
	: Account(date, id), credit(credit), rate(rate), fee(fee), acc(date, 0) { }

void CreditAccount::deposit(const Date &date, double amount, const string &desc) {
	record(date, amount, desc);
	acc.change(date, getDebt());
}

void CreditAccount::withdraw(const Date &date, double amount, const string &desc) {
	if (amount - getBalance() > credit) {
		error("not enough credit");
	} else {
		record(date, -amount, desc);
		acc.change(date, getDebt());
	}
}

void CreditAccount::settle(const Date &date) {
	double interest = acc.getSum(date) * rate;
	if (interest != 0)
		record(date, interest, " interest");
	if (date.getMonth() == 1)
		record(date, -fee, " annual fee");
	acc.reset(date, getDebt());
}

void CreditAccount::show() const {
	Account::show();
	cout << "\tAvailable credit:" << getAvailableCredit();
}

//main.cpp
#include "account.h"
#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;

struct deleter {
	template <class T> void operator () (T* p) { delete p; }
};

int main() {
	Date date(2008, 11, 1);	//起始日期
	vector<Account *> accounts;	//创建账户数组，元素个数为0
	cout << "(a)add account (d)deposit (w)withdraw (s)show (c)change day (n)next month (q)query (e)exit" << endl;
	char cmd;
	do {
		//显示日期和总金额
		date.show();
		cout << "\tTotal: " << Account::getTotal() << "\tcommand> ";

		char type;
		int index, day;
		double amount, credit, rate, fee;
		string id, desc;
		Account* account;
		Date date1, date2;

		cin >> cmd;
		switch (cmd) {
		case 'a':	//增加账户
			cin >> type >> id;
			if (type == 's') {
				cin >> rate;
				account = new SavingsAccount(date, id, rate);
			} else {
				cin >> credit >> rate >> fee;
				account = new CreditAccount(date, id, credit, rate, fee);
			}
			accounts.push_back(account);
			break;
		case 'd':	//存入现金
			cin >> index >> amount;
			getline(cin, desc);
			accounts[index]->deposit(date, amount, desc);
			break;
		case 'w':	//取出现金
			cin >> index >> amount;
			getline(cin, desc);
			accounts[index]->withdraw(date, amount, desc);
			break;
		case 's':	//查询各账户信息
			for (size_t i = 0; i < accounts.size(); i++) {
				cout << "[" << i << "] ";
				accounts[i]->show();
				cout << endl;
			}
			break;
		case 'c':	//改变日期
			cin >> day;
			if (day < date.getDay())
				cout << "You cannot specify a previous day";
			else if (day > date.getMaxDay())
				cout << "Invalid day";
			else
				date = Date(date.getYear(), date.getMonth(), day);
			break;
		case 'n':	//进入下个月
			if (date.getMonth() == 12)
				date = Date(date.getYear() + 1, 1, 1);
			else
				date = Date(date.getYear(), date.getMonth() + 1, 1);
			for (vector<Account*>::iterator iter = accounts.begin(); iter != accounts.end(); ++iter)
				(*iter)->settle(date);
			break;
		case 'q':	//查询一段时间内的账目
			date1 = Date::read();
			date2 = Date::read();
			Account::query(date1, date2);
			break;
		}
	} while (cmd != 'e');
	for_each(accounts.begin(), accounts.end(), deleter());
	return 0;
}