Question

我对ceil（）函数有疑问。我在下面的代码中尝试将C中的两个小数位向上舍入为变量monthlyPayment，并且输出中的ceil函数似乎被忽略。在图像中输出与它应该是的相比。 img

#include "stdafx.h"
#include "stdio.h"
#include "math.h"
#define MONTHS 12

int main()
{
    double principle;
    double rate;
    double numYears;
    double numMonths;
    double monthlyPayment;
    double monthlyRate;

    printf("Welcome to the morgage calculator.\nEnter your principal amount to get started. ");
    scanf_s("%lf", &principle);
    printf("Enter the yearly morgage interest rate ");
    scanf_s("%lf", &rate);
    printf("Enter the number of years ");
    scanf_s("%lf", &numYears);
    numMonths = numYears * MONTHS;
    monthlyRate = rate / MONTHS / 100;
    monthlyPayment = ((monthlyRate) / (1 - pow((1 + monthlyRate), (-numMonths)))* principle);
    monthlyPayment = monthlyPayment * 100;
    ceil(monthlyPayment);
    monthlyPayment = monthlyPayment / 100;
    double toPrince = 0.0;
    double interest = 0.0;
    printf("Your total monthly payment ammount:$ %.2lf\n", monthlyPayment);
    printf("Month\tPrinciple\tInterest\t $ to Principle\n");
        for (int index = 1; index <= numMonths;) {
            interest = principle * monthlyRate;
            toPrince = monthlyPayment - interest;   
            printf("%2d%16.2lf %16.2lf %16.2lf\n", index, principle, interest, toPrince);
            principle = principle - toPrince;
            index++;
        }
}

Answer 1

如果变量返回结果，

ceil()不会更改变量。应该是：

double result = ceil(var);

Answer 2

您可以通过观察C函数无法修改其参数来发现问题，除非您将指针传递给您想要修改的内容。这就是在调用scanf时添加＆符号的原因。

ceil(monthlyPayment)中没有＆符号，monthlyPayment不是指针;因此，不可能进行修改。

您可以修改monthlyPayment的汇总代码，如下所示：

monthlyPayment = ceil(monthlyPayment * 100) / 100;

函数ceil（）被忽略

2 个答案: