C＃中的乘法

Question

I'm new to C# and tried the following program on multiplication using Switch. The program is perfectly going thru the Switch cases, but the multiplied result is not displaying in the console. Can you please help:

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

Change your Console.Writeline to

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

and

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

You can also format Cost using {Cost:d} see https://docs.microsoft.com/en-us/dotnet/standard/base-types/composite-formatting .

It is also advisable that you don't use int.Parse because it will throw an error if a character is entered. So change the code to something like

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

You don't have to declare nSeats at the top, and it handles the error.

This is how I would've write the code

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

For clarity, simply use the following:

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

Answer 3

您缺少格式化程序{0}

 Console.WriteLine("Enterprise License Cost : ${0}", Cost);

Answer 4

Your are missing code to displaying actual result. You can try this:

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

etc.

Answer 5

Firstly, declare your Cost variable outside the switch statement. You can declare it along with your other variables. Secondly, assign and display the Cost variable in each case of the switch statement.

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

String formatting example:

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