Question

我正在尝试为我正在编写的C ++程序创建里程超时计算功能。我在使用此函数在switch语句中正常工作时遇到问题。我想要达到（或计算）的是里程数超过carSize里程限制*租用的天数。每个carSize都有不同的超额/英里计算率。

到目前为止我的代码是：

double calcMilesFee(int miles, int days, char carSize)
{
    double milesFee = 0;
    double compactOverageCharge = .05;
    double midSizeOverageCharge = .07;
    double fullSizeOverageCharge = .09;
    int compactDailyMilesLimit = 20;
    int midSizeDailyMilesLimit = 25;
    int fullSizeDailyMilesLimit = 30;

    switch (carSize)
    {
        case 'c':
        case 'C':
        {
            while (miles > compactDailyMilesLimit * days)
            {
                milesFee =  (miles * days) / compactDailyMilesLimit;
            }
            if (milesFee > compactDailyMilesLimit)
            {
                milesFee = milesFee * compactOverageCharge;
                cout << "Overage Fee is " << milesFee << endl;
                break;
            }
        }


        case 'm':
        case 'M':
        {
            while (miles > midSizeDailyMilesLimit * days)
            {
                milesFee =  (miles * days) / midSizeDailyMilesLimit;
            }
            if (milesFee > midSizeDailyMilesLimit)
            {
                milesFee = milesFee * midSizeOverageCharge;
                cout << "Overage Fee is " << milesFee << endl;
                break;
            }
        }

        case 'f':
        case 'F':
        {
            while (miles > fullSizeDailyMilesLimit * days)
            {
                milesFee =  (miles * days) / fullSizeDailyMilesLimit;
            }
            if (milesFee > fullSizeDailyMilesLimit)
            {
                milesFee = milesFee * fullSizeOverageCharge;
                cout << "Overage Fee is " << milesFee << endl;
                break;
            }
        }
    }
    return milesFee;

}

Answer 1

您的问题包括：

除了使用if条件外，您永远不会从每个开关案例标签中断。
你的while循环永远不会结束。 while循环体中没有任何内容可以改变条件。

那就是说，这个问题比你做出来的要简单得多：

#include <iostream>
#include <cmath>

double calcMilesFee(int miles, int days, char carSize)
{
    const double compactOverageCharge = .05;
    const double midSizeOverageCharge = .07;
    const double fullSizeOverageCharge = .09;
    const int compactDailyMilesLimit = 20;
    const int midSizeDailyMilesLimit = 25;
    const int fullSizeDailyMilesLimit = 30;
    double overageCharge = 0.0;
    int dailyMilesLimit = 0;
    double milesFee = 0;

    switch (carSize)
    {
        case 'c':
        case 'C':
            dailyMilesLimit = compactDailyMilesLimit;
            overageCharge = compactOverageCharge;
            break;

        case 'm':
        case 'M':
            dailyMilesLimit = midSizeDailyMilesLimit;
            overageCharge = midSizeOverageCharge;
            break;

        case 'f':
        case 'F':
            dailyMilesLimit = fullSizeDailyMilesLimit;
            overageCharge = fullSizeOverageCharge;
            break;
    }

    milesFee = std::max(0, miles - (days * dailyMilesLimit)) * overageCharge;
    std::cout << "Overage Fee is " << milesFee << std::endl;
    return milesFee;
}

正如我在评论中提到的，我建议不要使用浮点进行货币计算，除非您的任务是强制性的。你可以把最终结果作为一个浮点值，但是我写这个我会使用整数精度到一些硬限制（比如十分之一便士）并执行浮点转换一次和最后

Answer 2

每个案例陈述都应以break结尾。在您的情况下，如果任何内部if语句失败，则不会使下一个case语句执行而导致不同的行为。

租车里程超额计算功能

2 个答案: