c# - 如果/如果其他/其他

Question

我是 C# 新手，遇到以下问题。

计算车辆应缴纳税款的程序。用户输入汽车类型(有 3 种类型)、许可证长度(6 或 12 个月)和排放范围(5 种类型)，程序打印出许可证费用:

只要我选择 6 个月的许可长度，我的代码就可以完美运行。

请帮助我理解我犯了什么错误，谢谢。

static void Main(string[] args)
    {
        bool check;
        int car, length;
        double rate = 0;
        string band = "";


        Console.WriteLine("{0,-12} {1,-12} {2,-12}", "Diesel Car", "Petrol Car", "Alt. Fuel Car");
        Console.WriteLine("{0,-12} {1,-12} {2,-12}", "TC 49", "TC 48", "TC 59");

        Console.WriteLine("Enter Car Type (TC #): ");
        check = int.TryParse(Console.ReadLine(), out car);
        if (check)
        {
            if (car == 49)
            {

                    Console.WriteLine("Enter Licience length in months(6 or 12)");
                    length = int.Parse(Console.ReadLine());
                    if (length == 6)
                    {
                        Console.WriteLine("Enter Emission Band (AA, A, B, C, D): ");
                        band = Console.ReadLine();
                        if (band == "AA")
                        {
                            rate = 44;
                        }
                        else if (band == "A")
                        {
                            rate = 60.5;
                        }
                        else if (band == "B")
                        {
                            rate = 71.5;
                        }
                        else if (band == "C")
                        {
                            rate = 82.5;
                        }
                        else if (band == "D")
                        {
                            rate = 88;
                        }
                        else
                            Console.WriteLine("ERROR"); //error for band != AA,A,B,C or D

                    }
                    else if (length == 12)
                    {
                        if (band == "AA")
                        {
                            rate = 80;
                        }
                        else if (band == "A")
                        {
                            rate = 110;
                        }
                        else if (band == "B")
                        {
                            rate = 130;
                        }
                        else if (band == "C")
                        {
                            rate = 150;
                        }
                        else if (band == "D")
                        {
                            rate = 160;
                        }
                        else
                            Console.WriteLine("ERROR"); //error for band != AA,A,B,C or D 
                    }
                    else
                        Console.WriteLine("ERROR"); // error for length != 6 or 12

            }
            else if (car == 48)
            {
                Console.WriteLine("Enter Licience length in months(6 or 12)");
                length = int.Parse(Console.ReadLine());
                if (length == 6)
                {
                    Console.WriteLine("Enter Emission Band (AA, A, B, C, D): ");
                    band = Console.ReadLine();
                    if (band == "AA")
                    {
                        rate = 38.5;
                    }
                    else if (band == "A")
                    {
                        rate = 55;
                    }
                    else if (band == "B")
                    {
                        rate = 66;
                    }
                    else if (band == "C")
                    {
                        rate = 77;
                    }
                    else if (band == "D")
                    {
                        rate = 85.25;
                    }
                    else
                        Console.WriteLine("ERROR"); //error for band != AA,A,B,C or D

                }
                else if (length == 12)
                {
                    if (band == "AA")
                    {
                        rate = 70;
                    }
                    else if (band == "A")
                    {
                        rate = 100;
                    }
                    else if (band == "B")
                    {
                        rate = 120;
                    }
                    else if (band == "C")
                    {
                        rate = 140;
                    }
                    else if (band == "D")
                    {
                        rate = 155;
                    }
                    else
                        Console.WriteLine("ERROR"); //error for band != AA,A,B,C or D 
                }
                else
                    Console.WriteLine("ERROR"); // error for length != 6 or 12
            }
            else if (car == 59)
            {
                Console.WriteLine("Enter Licience length in months(6 or 12)");
                length = int.Parse(Console.ReadLine());
                if (length == 6)
                {
                    Console.WriteLine("Enter Emission Band (AA, A, B, C, D): ");
                    band = Console.ReadLine();
                    if (band == "AA")
                    {
                        rate = 33;
                    }
                    else if (band == "A")
                    {
                        rate = 49.5;
                    }
                    else if (band == "B")
                    {
                        rate = 60.5;
                    }
                    else if (band == "C")
                    {
                        rate = 71.5;
                    }
                    else if (band == "D")
                    {
                        rate = 82.5;
                    }
                    else
                        Console.WriteLine("ERROR"); //error for band != AA,A,B,C or D

                }
                else if (length == 12)
                {
                    if (band == "AA")
                    {
                        rate = 60;
                    }
                    else if (band == "A")
                    {
                        rate = 90;
                    }
                    else if (band == "B")
                    {
                        rate = 110;
                    }
                    else if (band == "C")
                    {
                        rate = 130;
                    }
                    else if (band == "D")
                    {
                        rate = 150;
                    }
                    else
                        Console.WriteLine("ERROR"); //error for band != AA,A,B,C or D 
                }
                else
                    Console.WriteLine("ERROR"); // error for length != 6 or 12
            }
            else
                Console.WriteLine("ERROR"); // error for car number != 48,49 or 59
        }
        else
            Console.WriteLine("ERROR"); //error for car num != int
        Console.WriteLine(rate);
    }

Answer 1

你的代码中有多个概念问题，但你的问题为什么不起作用是因为:

if (length == 6)
{
    Console.WriteLine("Enter Emission Band (AA, A, B, C, D): ");
    band = Console.ReadLine();
    //..other stuff
}
else if (length == 12)
{
    //here band has his initial value
}

所以你需要询问if(length == 6)

之外的band

如何改进代码。嵌套 if 是非常糟糕的做法，因此您应该始终考虑编写没有箭头结构的代码(嵌套 if)。

public static void Main()
{
    int car = 0;
    int length = 0;
    Console.WriteLine("Enter Car Type (TC #): ");

    if(!int.TryParse(Console.ReadLine(), out car))
    {
        Console.WriteLine("Not valid number");
        return;
    }

     Console.WriteLine("Enter Licience length in months(6 or 12)");
     if(!int.TryParse(Console.ReadLine(), out length))
     {
         Console.WriteLine("Not valid number");
         return;
     }

     Console.WriteLine("Enter Emission Band (AA, A, B, C, D): ");
     string band = Console.ReadLine();

     Dictionary<Tuple<int,int,string>, decimal> carDataDic = GetCarDetails();

     decimal ratio = 0;

     Tuple<int, int, string> checkRatioKey = new Tuple<int, int, string>(car, length, band);

     if(!carDataDic.TryGetValue(checkRatioKey, out ratio))
     {
         Console.WriteLine("No value found for input data");
         return;
     }

     Console.WriteLine("Ratio is: " + ratio);
}

public static Dictionary<Tuple<int,int,string>, decimal> GetCarDetails()
{
     Dictionary<Tuple<int,int,string>, decimal> values= new Dictionary<Tuple<int,int,string>, decimal>();

     //Tuple Items -> Item1=car, Item2=length, Item3= band), value in Dictionary is the rate which you should have
     values.Add(new Tuple<int, int, string>(49, 6, "AA"), 44);
     values.Add(new Tuple<int, int, string>(49, 6, "A"), 60.5);
     //define all of your cases.

     return values;
}

Tuple 具有类的作用，您可以在其中存储特定于汽车的数据。它很好用，因为您可以将它用作 Dictionary 中的键。