我试着做了一个计算电价的c语言程序，但是一行行不通

Question

我试着做了一个计算电价的c语言程序，但是一行不行。

这是我的代码。

#include <stdio.h>

int main()
{
    int usageElectric;      //amount of electricity used
    int basicMoney;         //basic price
    int totalMoney;         //total price
    double usageMoneyPerKw; //kw per used price
    double totalFinalMoney; //final usage price
    double tax;             //tax


    printf("put in the amount of electricity used (kw) : ");  //put in 150kw.
    scanf("%d", &usageElectric);

    basicMoney = 660;   //basic price = 0
    usageMoneyPerKw = 88.5; //kw per usage price : .5
    totalMoney = basicMoney + (usageElectric * usageMoneyPerKw);    

    tax = totalMoney * (9 / 100);   //This line is the problem line = doesn't work

    totalFinalMoney = totalMoney + tax; 

    printf("Tax is %d\n", tax);  // a line to show that the tax isn't being caluculated properly

    printf("The final usage price is %lf.", totalFinalMoney);

    return 0;
}

如果输入为 150(kw)，则 totalFinalMoney 应为 $15189.150000

任何人都可以帮我解决为什么这条线不起作用吗？

tax = totalMoney * (9 / 100);

如果正常运行，结果应该如下：

tax = 13935 * (9/100) = 1254.15

因此，最终结果应该是：

The final usage price is 15189.150000

Answer 1

在子表达式9/100中，两个操作数都是整数，所以除法是整数除法，意味着任何小数部分都被截断，所以它的计算结果为0。

如果改为浮点常量，就会得到浮点除法。所以把上面的改成：

9.0/100.0

或者简单地说：

0.09

Answer 2

您只需像这样 ((double)9 / 100) 进行类型转换 (9/10)。从现在开始，它正在将 9/10 的输出视为整数并将结果作为 0.

并且在打印 tax 时，您应该使用 %lf 而不是 %d。

#include <bits/stdc++.h>

using namespace std;

int main()
{

    int usageElectric;      //amount of electricity used
    int basicMoney;         //basic price
    int totalMoney;         //total price
    double usageMoneyPerKw; //kw per used price
    double totalFinalMoney; //final usage price
    double tax;             //tax


    printf("put in the amount of electricity used (kw) : ");  //put in 150kw.
    scanf("%d", &usageElectric);

    basicMoney = 660;   //basic price = 0
    usageMoneyPerKw = 88.5; //kw per usage price : .5
    totalMoney = basicMoney + (usageElectric * usageMoneyPerKw);    

    tax = totalMoney * ((double)9 / 100);   //This line is the problem line = doesn't work

    totalFinalMoney = totalMoney + tax; 

    printf("Tax is %lf\n", tax);  // a line to show that the tax isn't being caluculated properly

    printf("The final usage price is %lf.", totalFinalMoney);
}

我试着做了一个计算电价的c语言程序，但是一行行不通

I tried making a electricity price calculating c language program, but one line doesn't work

c

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