C# 中的乘法

Question

我是 C# 新手，使用 Switch 尝试了以下乘法程序。该程序完美地通过了 Switch 案例，但相乘结果未显示在控制台中。你能帮忙吗：

using System;

public class Program
{
 public static void Main(string[] args)
 {
    int _pLicense = 50;
    int _sLicense = 100;
    int _eLicense = 150;
    String lType;
    int nSeats;
Console.WriteLine("\n1.Personal License\n2.Startup License\n3.Enterprise License");
        Console.WriteLine("Enter the license type");
        lType = Console.ReadLine();
        //lType = char.Parse(Console.ReadLine());


switch(lType)
    {
        case "1":
            Console.WriteLine("Enter the number of seats");
            nSeats = int.Parse(Console.ReadLine());
            //Console.WriteLine(_pLicense);
            int Cost = _pLicense*nSeats;
            Console.WriteLine("Personal License Cost : $", +Cost);
            break;
        case "2":
            Console.WriteLine("Enter the number of seats");
            nSeats = int.Parse(Console.ReadLine());
            //Console.WriteLine(_sLicense);
            Cost = (_sLicense * nSeats);
            Console.WriteLine("Startup License Cost : $", Cost);
            break;
        case "3":
            Console.WriteLine("Enter the number of seats");
            nSeats = int.Parse(Console.ReadLine());
            //Console.WriteLine(_pLicense);
            Cost = (_eLicense * nSeats);
            Console.WriteLine("Enterprise License Cost : $", Cost);
            break;
        default:
        Console.WriteLine("Invalid Type");
           break;
    }
}

}

Answer 1

将您的 Console.Writeline 更改为

Console.WriteLine($"Personal License Cost : ${Cost}");

和

Console.WriteLine($"Enterprise License Cost : ${Cost}");

您还可以使用 {Cost:d} 设置成本格式，请参阅 https://docs.microsoft.com/en-us/dotnet/standard/base-types/composite-formatting。

最好不要使用int.Parse，因为输入字符会报错。所以将代码更改为

if(int.TryParse(Console.ReadLine(), out int nSeats)
{
    Console.WriteLine($"Enterprise License Cost : ${Cost}");
}
else
{
    //Try again
}

您不必在顶部声明 nSeats，它会处理错误。

这就是我编写代码的方式

public static void Main(string[] args)
{
    int nSeats = 0;
    Console.WriteLine("\n1.Personal License\n2.Startup License\n3.Enterprise License");
    Console.WriteLine("Enter the license type");
    var lType = Console.ReadLine();  //ReadLine returns a string, so it will automatically make lType a string
    int _LicenseCost = lType == "1" ? 50 : lType == "2" ? 100 : lType == "3" ? 150 : 0;
    if(_LicenseCost > 0)
    {
        while(true)
        {
            Console.WriteLine("Enter the number of seats");
            if(int.TryParse(Console.ReadLine(), out nSeats))
                break;
            else
                Console.WriteLine("Please enter a valid number");
        }
        Console.WriteLine((lType == "1" ? "Personal" : lType == "2" ? "Startup" : lType == "3" ? "Enterprise" : "") + $" License Cost : ${_LicenseCost * nSeats}");
    }
    else
        Console.WriteLine("License type is not valid. Good bye!");
}

Answer 2

您缺少像 {0}

这样的格式化程序

 Console.WriteLine("Enterprise License Cost : [=10=]", Cost);

Answer 3

您缺少显示实际结果的代码。你可以试试这个：

Console.WriteLine("Personal licence : " + cost);

等等

Answer 4

为清楚起见，只需使用以下内容：

var cost = (_sLicense * nSeats);
Console.WriteLine("Startup License Cost : " + cost);

Answer 5

首先，在 switch 语句之外声明您的 Cost 变量。您可以将其与其他变量一起声明。其次，在switch语句的每个case中赋值并显示Cost变量。

using System;

public class Program
{
 public static void Main(string[] args)
 {
    int _pLicense = 50;
    int _sLicense = 100;
    int _eLicense = 150;
    String lType;
    int nSeats;
    int Cost;

Console.WriteLine("\n1.Personal License\n2.Startup License\n3.Enterprise License");
        Console.WriteLine("Enter the license type");
        lType = Console.ReadLine();
        //lType = char.Parse(Console.ReadLine());


switch(lType)
    {
        case "1":
            Console.WriteLine("Enter the number of seats");
            nSeats = int.Parse(Console.ReadLine());
            //Console.WriteLine(_pLicense);
            Cost = _pLicense*nSeats;
            Console.WriteLine("Personal License Cost : $" + Cost);
            break;
        case "2":
            Console.WriteLine("Enter the number of seats");
            nSeats = int.Parse(Console.ReadLine());
            //Console.WriteLine(_sLicense);
            Cost = (_sLicense * nSeats);
            Console.WriteLine("Startup License Cost : $" + Cost);
            break;
        case "3":
            Console.WriteLine("Enter the number of seats");
            nSeats = int.Parse(Console.ReadLine());
            //Console.WriteLine(_pLicense);
            Cost = (_eLicense * nSeats);
            Console.WriteLine("Enterprise License Cost : $" + Cost);
            break;
        default:
        Console.WriteLine("Invalid Type");
           break;
    }
}

Answer 6

字符串格式示例：

string name = "Fred";
String.Format("Name = {0}, hours = {1:hh}", name, DateTime.Now);

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