Question

我正在尝试接受用户输入，然后使用该输入来计算图表，但每次设置该值时，该值都会重置为初始值为零。我知道这是因为方法StraightLineDepreciation()正在返回一条消息，告诉我我没有输入一个数字，只有在值为0时返回，这就是初始值。它似乎在断开开关循环后重置。这是我的计划。

    static void Main(string[] args)
    {
        double amount = 0;
        int years = 0;
        char menuItem;
        Console.WriteLine("This program computes depreciation tables using various methods of depreciation");
        menuItem = GetMenuChoice();
        while (menuItem != 'Q')
        {
            ProcessMenuItem(menuItem,amount,years);
            menuItem = GetMenuChoice();
        }           
        Console.WriteLine("Goodbye!");
        Console.ReadLine();
    }



    static void ProcessMenuItem(char menuItem, double amount, int years)
    {
        switch (menuItem)
        {
            case 'A':
                ProcessSetValues(ref amount, ref years);
                Console.WriteLine("{0} {1}", amount, years);
                break;
            case 'B':
                StraightLineDepreciation( amount, years);
                break;
            case 'C':
                break;
            case 'D':
                break;
        }
    }
    static void ProcessSetValues(ref double amount, ref int years)
    {
        amount = GetPositiveDouble("How much money is to be depreciated?");
        years = GetPositiveInteger("Over how many years");
        return;

    }
    static void StraightLineDepreciation( double amount,  int years)
    {
        if(amount != 0 && years != 0)
        {
            amount = amount / years;
            Console.WriteLine("Year    Depreciation");
            Console.WriteLine("---- ---------------");
            for (int counter = 0; counter < years; counter++)
            {
                Console.WriteLine("    {0,+6}{1}", amount, years);
            }
        }
        else
        {
            Console.WriteLine("You have not entered any values for the amount and years.");
        }
    }

Answer 1

你能否确保所有出现的方法都通过ref，因为我认为这就是问题所在：

ProcessMenuItem(ref menuItem,ref amount,ref years);
StraightLineDepreciation( ref amount, ref years);

或者只是创建一个包装类并传递引用类型而不是使用值类型。

class DepreciationTracker
{
    double amount;
    int years;
}

ProcessMenuItem( DepreciationTracker obj)
{
     //modify obj
}
StraightLineDepreciation( DepreciationTracker obj)
{
     //modify obj
}

还会在Value vs Reference Types上推荐一本入门书。

C＃值在断开开关盒后重置

1 个答案: