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這個例子在前例的基礎(chǔ)上添加了如下內(nèi)容：
- 為SavingsAccount類添加一個靜態(tài)數(shù)據(jù)成員total凶朗，用來記錄各個賬戶的總金額毅否，并為其添加了相應(yīng)的靜態(tài)成員函數(shù)getTotal對其進行訪問；
- 將getBalance失息，accumulate等不需要改變對象狀態(tài)的成員函數(shù)聲明為常成員函數(shù)；
- 對程序結(jié)構(gòu)進行了調(diào)整：將SavingsAccount類從主函數(shù)所在的源函數(shù)分開档址，建立兩個新的文件account.h和account.cpp分別存放SavingsAccount類的定義和實現(xiàn)盹兢；
代碼如下：
//account.h
#ifndef _ACCOUNT_H_
#define _ACCOUNT_H_
class SavingsAccount {
public:
SavingsAccount(int date, int id, double rate);//構(gòu)造函數(shù)
int getId() const { return id; }
double getBalance() const { return balance; }
double getRate() const { return rate; }
void show() const;
void deposit(int date, double amount);//取錢
void withdraw(int date, double amount);//存錢
void settle(int date);//結(jié)算利息，假設(shè)每年1月1號結(jié)算一次
static double getTotal() { return total; }
private:
int id;
double balance;
double rate;
int lastDate;
double accumulation;//計算賬戶余額的按日累計值
//記錄一筆賬守伸，date為日期绎秒，amount為金額
static double total;
void record(int date, double amount);
double accumulate(int date) const {
return accumulation + (date - lastDate)*balance;
}
};
#endif
//account.cpp
#include "account.h"
#include <cmath>
#include <iostream>
using namespace std;
double SavingsAccount::total =0;
SavingsAccount::SavingsAccount(int date, int id, double rate)
:id(id), balance(0), rate(rate), lastDate(date), accumulation(0) {
cout << date << "\t#" << id << " is created" << endl;
}
void SavingsAccount::record(int date, double amount) {
accumulate(date);
lastDate = date;
amount = floor(amount * 100 + 0.5) / 100;//保留小數(shù)點后兩位
balance = balance + amount;
total = total + amount;
cout << date << "\t#" << id << "\t" << balance << endl;
}
void SavingsAccount::deposit(int date, double amount) {
record(date, amount);
}
void SavingsAccount::withdraw(int date, double amount) {
if (amount > getBalance())
cout << "Error: not enough money" << endl;
else
record(date, -amount);
}
void SavingsAccount::settle(int date) {
double interest = accumulate(date)*rate / 365;
if (interest != 0)
record(date, interest);
accumulation = 0;
}
void SavingsAccount::show() const {
cout << "#" << id << "\tBalance:" << balance << endl;
}
//test.cpp
#include "account.h"
#include <iostream>
using namespace std;
int main() {
//建幾個賬戶
SavingsAccount sa0(1, 21325302, 0.015);
SavingsAccount sa1(1, 58320212, 0.015);
//幾筆賬目
sa0.deposit(5, 5000);
sa1.deposit(25, 100000);
sa0.deposit(45, 5500);
sa1.withdraw(60, 4000);
//假設(shè)開戶90天到了銀行的計息日，結(jié)算所有賬戶的年息
sa0.settle(90);
sa1.settle(90);
//輸出各個賬戶的信息
sa0.show();
cout << endl;
sa1.show();
cout << endl;
cout << "Total:" << SavingsAccount::getTotal() << endl;
return 0;
}
Here is the result
