2020春c++计算存款利息

Posted 2021-03-01 zhaoyiyao

创建一个SavingAccount类. 使用一个static数据成员annualInterestRate保存每个存款者的年利率。类的每个对象都包含一个private数据成员savingBalance，用以指示存款者目前的存款金额。该类提供成员函数calculateMonthlyInterest，它将余额乘以annualInterestRate再除以12来计算月利息，这个利息应该加到savingBalance中。该类还提供一个static成员函数modifyInterestRate，它将static的annualInterestRate设置为一个新值。在主函数中，实例化SavingAccount类的两个对象saver1和saver2，余额分别是2000和3000，将annualInterestRate设置为3%，然后计算月利率并打印每个存款者的新余额，接着再将annualInterestRate设置为4%，计算下一个月的利息并打印每个存款者的新余额。
#include "stdafx.h"
#include<iostream>
#include<stdlib.h>
#include<iomanip>
using namespace std;

class SavingsAccount
{
public:
SavingsAccount(double save):savingBalance(save){}
double calculateMonthlyInterest();
void printBalance();
static double modifyInterestRate(double rate);

private:
static double annualInterestRate;
double savingBalance;
};
double SavingsAccount::annualInterestRate=0;
double SavingsAccount::modifyInterestRate(double rate){
annualInterestRate=rate;
return annualInterestRate;
}
double SavingsAccount::calculateMonthlyInterest(){
savingBalance+=savingBalance*annualInterestRate/12;
return savingBalance;
}
void SavingsAccount::printBalance(){
cout<<"$"<<setiosflags(ios::fixed)<<setprecision(2)<<savingBalance<<endl;
}

 

int main(){
SavingsAccount saver1(2000.0);
SavingsAccount saver2(3000.0);
SavingsAccount::modifyInterestRate(0.03);

cout<<"Initial balances:\nSaver 1:";
saver1.printBalance();
cout<<"Saver 2：";
saver2.printBalance();

saver1.calculateMonthlyInterest();
saver2.calculateMonthlyInterest();

cout<<"\n \nBalances after 1 month‘s interest applied at .03 \n"<<"Saver 1:";
saver1.printBalance();
cout<<"Saver 2:";
saver2.printBalance();

SavingsAccount::modifyInterestRate(0.04);
//change interest rate
saver1.calculateMonthlyInterest();
saver2.calculateMonthlyInterest();

cout<<"\n\nBalances after 1 month‘s interest applied at: .04\n"<<"Saver 1:";
saver1.printBalance();
cout<<"Saver 2:";
saver2.printBalance();
cout<<endl;
getchar();
return 0;
}