C++ 使用用户输入和指数查找现值

Question

我需要帮助来计算现值。用户将输入：支付金额（payamt）、期限（trm）和利率（intrte）。我在计算以下等式时遇到问题：

现值=支付金额*（（1-（1+利息）^-期限）/利率）

这是我目前的代码：

#include <iostream>
using namespace std;

int main()

{
int trm = 0
    ;

double intrte = 0.0
    ;

float payamt = 0.0,
    presVal = 1
    ;

char
    response = '\0'
    ;

    cout << "Would you like to compute a present value? Enter Y for yes; N for no.";
    cin >> response;

    if (response != 'Y') {
        return 0;
    }

    cout << "\nPayment Amount: $";                  //payment in $ and cents for each year
    cin >> payamt;

    cout << "\nTerm (in years): ";                  //term number of years of payments
    cin >> trm;

    cout << "\nInterest Rate (between 0 and 100): ";//interest rate
    cin >> intrte;

    cout << "\n\nThe present value for a payment amount of $" << payamt
    << " and an interest rate of " << intrte
    << "%, and a term of " << trm
    << " years is $" << presVal
    << ".\n\n" << endl;

    presVal == payamt * (1 - ((1 + intrte), (-trm)))/intrte;
}

Answer 1

当您包含 cmath (#include <cmath>) 时，您可以使用 double pow(double base, double exponent) 函数将一个数字乘以另一个数字的幂。更多信息可以在这里找到：http://www.cplusplus.com/reference/cmath/pow/

你的公式变成了： presVal = payamt * (1 - pow(1+intrte, -trm))/intrte;