Question

我在C ++中还很陌生，遇到了一些麻烦。为此，我正在尝试创建抵押计算器。我遇到的问题是它没有打印出正确的月付款和总还款额。这是我到目前为止所拥有的：

#include <iostream>
#include <iomanip>
#include <cmath>

using namespace std;

int main () {

    double annualInterestRate(0); // yearly interest rate
    double loanAmount(0); // the amount of the loan
    double monthlyInterestRate(0); // interest rate amount monthly
    double numberofPayments(0); // the amount of payments
    double totalYearsToRepay(0); // years needed to payback
    double totalPayBack(0); // total amount being paid back
    double monthlyPayment(0); 

    while (true) {

        cout << "Enter the amount of the loan:";
        cin >> loanAmount;

        cout << "Enter annual interest rate in decimal term (example 0.075):";
        cin >> annualInterestRate;

        cout << "Enter the length of the loan in years:";
        cin >> totalYearsToRepay;

        loanAmount = loanAmount;

        cout << "loanAmount: $" << setprecision(2) << fixed << loanAmount << endl;

        annualInterestRate = annualInterestRate;

        cout << "annualInterestRate: $" << setprecision(5) << fixed << annualInterestRate << endl;

        cout << "totalYearsToRepay: " << setprecision(0) << fixed << totalYearsToRepay << endl;

        // find monthly interest rate.
        monthlyInterestRate=annualInterestRate / 12;

        totalYearsToRepay = totalYearsToRepay;

        numberofPayments = totalYearsToRepay* 12;

        monthlyPayment = (loanAmount * (monthlyInterestRate) * totalYearsToRepay) / (totalYearsToRepay-1);

        cout << "Monthly Payment: $" << setprecision(2) << fixed << monthlyPayment << endl;

        totalPayBack = (monthlyPayment) * (numberofPayments);

        cout << "Total Pay Back: $" << setprecision (2) << fixed << totalPayBack << endl;

    }
}

这是应打印内容的示例：

Loan Amount: $50000.00
Annual Interest Rate: 0.06250 
Years to repay: 10
Monthly Payment: $561.40 
Total Pay Back: $67368.06

我没有得到每月的还款额和总还款额。我不知道数学部分出了什么问题。请帮忙！给定的公式为monthly payment= loanAmount * monthlyInterestRate * powerFactor / powerFactor -1，其中powerFactor = (1+monthlyInterestRate)^numberofpayments

Answer 1

我将使用此处https://www.thecalculatorsite.com/articles/finance/compound-interest-formula.php

所述的公式

然后我将A值除以该人必须还清该公式中称为A的总价的月份数。

您正在寻找所谓的“复合利率”。

Answer 2

在发布的代码中有此行

monthlyPayment = (loanAmount * (monthlyInterestRate) * totalYearsToRepay)
               / (totalYearsToRepay-1);

在评论中，OP清除

给出的公式是：
每月付款=贷款金额*每月利率* powerFactor / powerFactor-1
在哪里
powerFactor =（1+每月利率）^付款次数

可以将其转换为这些C ++代码行：

double powerFactor = std::pow(1.0 + monthlyInterestRate, numberofPayments);
double monthlyPayment = loanAmount * monthlyInterestRate * powerFactor
                      / (powerFactor - 1.0);
//  The parenthesis, here, are needed, due to standard math operator precedence

值得注意的是，代码还包含其他问题，例如分配给自己的变量或永无止境的循环

while (true)
{
    // Put a break statement somewhere or change the condition
}

C ++抵押贷款计算器

2 个答案: