c# - 开关的返回值始终为 0

Question

我正在为学校做一个项目，我正在尝试计算汽车在一定距离内的油耗，但开关始终返回 0。我尝试了不同的方法，但似乎都不起作用。

    public Double DetermineFuelConsumption (String Car, Double Kilometers)
    {
        Double FuelConsumption = 0;

        switch (Car)
        {
            // (14 / 100) ---> Liters per 100 Kilometers
            case "LaFerrari":
                FuelConsumption = (14 / 100) * Kilometers;
                break;
            case "Nissan GT-R Nismo":
                FuelConsumption = (12 / 100) * Kilometers;
                break;
            case "Pagani Huayra":
                FuelConsumption = (18 / 100) * Kilometers;
                break;
            case "McLaren P1":
                FuelConsumption = (8 / 100) * Kilometers;
                break;
            case "Lamborghini Aventador":
                FuelConsumption = (16 / 100) * Kilometers;
                break;
            case "Smart":
                FuelConsumption = (4 / 100) * Kilometers;
                break;
            case "Porsche 911":
                FuelConsumption = (9 / 100) * Kilometers;
                break;
            case "Audi R8":
                FuelConsumption = (15 / 100) * Kilometers;
                break;
        }
        return FuelConsumption;
    }

Answer 1

所有这些数字除以 100 都会得到 0。

这是整数除法:一个整数除以一个整数的结果总是一个整数。您需要指定您的数字是浮点类型:

public Double DetermineFuelConsumption (String Car, Double Kilometers)
{
    Double FuelConsumption = 0;

    switch (Car)
    {
        // (14 / 100) ---> Liters per 100 Kilometers
        case "LaFerrari":
            FuelConsumption = (14d / 100d) * Kilometers;
            break;
        case "Nissan GT-R Nismo":
            FuelConsumption = (12d / 100d) * Kilometers;
            break;
        case "Pagani Huayra":
            FuelConsumption = (18d / 100d) * Kilometers;
            break;
        case "McLaren P1":
            FuelConsumption = (8d / 100d) * Kilometers;
            break;
        case "Lamborghini Aventador":
            FuelConsumption = (16d / 100d) * Kilometers;
            break;
        case "Smart":
            FuelConsumption = (4d / 100d) * Kilometers;
            break;
        case "Porsche 911":
            FuelConsumption = (9d / 100d) * Kilometers;
            break;
        case "Audi R8":
            FuelConsumption = (15d / 100d) * Kilometers;
            break;
    }
    return FuelConsumption;
}

这里，d 后缀指定这些数字是 double ，而不是整数。