c++ - 我怎样才能让这个函数运行不止一次？

Question

首先请注意，我是 C++ 的绝对初学者。所以，请放轻松。

我一直在编写下面的代码，作为今年夏天我的编程方法论类(class)作业的一部分。它是一个银行程序，需要用户输入来计算用户贷款的月数 (n)、利率 (i) 和每月还款额。然后，该程序应该从用户那里获取付款金额并计算新的余额。从这里开始，它应该打印一份摊销报告，描述期初余额、支付的利息、支付的本金和期末余额。所有这一切都很好，但下一部分我遇到了麻烦。该程序应该能够接受多次付款并在摊销报告中添加额外的行，但我无法弄清楚如何再次运行“付款”功能来获得这些额外付款。请帮忙!!

此外，我知道为成员函数设置的参数几乎是不必要的，因为它们被用户输入所取代，但教师在作业说明中要求它们。

再次感谢您提供的任何建议!

#ifndef LOAN_DATA_H
#define LOAN_DATA_H

class Loan_Data
{
private:
    double  Bal;
    double  n;
    double  i;
    double  A;
        double p;

public:
            Loan_Data(double p, double n, double i);
    void    MakePayment(double pay);
    void    PrintAmortizationSchedule();
};

#endif  /* LOAN_DATA_H */




#include <cstdlib>
#include <cmath>
#include <iostream>
#include "Loan_Data.h"

using namespace std;


Loan_Data::Loan_Data(double p, double n, double i)
{
    cout << "Enter the loan amount: $";
    cin >> this->p;
    cout << "Enter the loan length: ";
    cin >> this->n;
    cout << "Enter your credit score: ";
    cin >> this->i;

    this->i = this->i / 100;
    this->i = this->i / 12;
    this->n = this->n * 12;
    Bal = this->p;
    A = (this->p * ((this->i * pow(1 + this->i, n)) / (pow(1 + this->i, n) - 1)));

    cout << "A is: " << A << endl;
    cout << "Bal is: " << Bal << endl;
    cout << "i is: " << this->i << endl;
}
void Loan_Data::MakePayment(double pay)
{
    cout << "i is: " << i << endl;
    cout << "Bal is: " << Bal << endl;
    cout << "Enter payment first payment amount: $";
    cin >> pay;

    cout << "Bal is: " << Bal << endl;

    Bal = ((i + 1) * Bal) - pay;
      A = pay;  
}

void Loan_Data::PrintAmortizationSchedule()
{
    double iP = (i * Bal);
    double pP = (A - (i*Bal));
    double endingBalance = ((1 + i)*Bal - A);
    double payment2 = (i + 1)*Bal;

    cout << "Beginning Bal." << "\t""\t" << cout << "Interest paid" << "\t""\t" << cout << "Principle paid" << "\t""\t" << cout << "Ending Bal." << "\t""\t" << endl;

     if ((i + 1)*Bal > A)
     {
         cout << p << "\t""\t""\t""\t" << iP << "\t""\t""\t""\t" << pP << "\t\t""\t""\t" << endingBalance << endl;
         endingBalance = Bal;
     }
     else if (Bal < A)
     {
         cout << Bal << "\t""\t""\t""\t" << iP << "\t""\t""\t""\t" << (payment2 - (i*Bal)) << "\t\t""\t""\t" << ((1 + i)*Bal - payment2) << endl;
         Bal = ((1 + i)*Bal - payment2);
     }
     else if (Bal == 0)
     {
         cout << "0" << "\t""\t""\t""\t""\t" << "0" << "\t""\t""\t""\t""\t" << "0" << "\t\t""\t""\t""\t" << "0" << endl;
     }

}

int main(int argc, char *argv[])
{
    double Bal;
    double p;
    double n;
    double i;
    double pay;
    double A; 


    Loan_Data loan1(p, n, i);

    loan1.MakePayment(pay);

    loan1.PrintAmortizationSchedule();

    return 0;

}

Answer 1

使用 do while 修改您的 main 循环 --

int main(int argc, char *argv[])
{
 char ch='n';
do {
 double Bal;
 double p;
 double n;
 double i;
 double pay;
 double A;
 Loan_Data loan1(p, n, i);
 loan1.MakePayment(pay);
 loan1.PrintAmortizationSchedule();
 printf("Do you want to continue ");
 ch=getchar();
 }while(ch=='y');
return 0;

}

当条件为真时执行 while 循环重复封闭的代码，即如果用户在第一次结束时输入 y 程序将继续，否则它将退出。