c# Command Line arguments

Question

I am trying to make my program run from commands line arguments, so i have 3 options in my code that you can choose to run.

The question is that i want to parse the port along with the arguments, how do i do that?

Each option has a different program configuration. My attempt show below; so inside the the program i also want to pass the the port as a argument so when i write "program 1 5656" in the console. The application sees that its the first option 1 to run and then parses the 5656 into the port variable.

I tried below but when i enter the command it gives me the wrong option as in it start option 2 instead of 1.

class MainClass
{
    static void Main(string[] args)
    {
        // Test if input arguments were supplied:
        if (args.Length == 1)
        {
            int port = int.Parse(args[1]);
            server = new TcpListener(IPAddress.Any, port);
            //Rest of the program
        }
        if (args.Length == 2)
        {
            int port = int.Parse(args[2]);
            server = new TcpListener(IPAddress.Any, port);
            //Rest of the program
        }
        if (args.Length == 3)
        {
            int port = int.Parse(args[3]);
            server = new TcpListener(IPAddress.Any, port);
            //Rest of the program
        }
    }
}

The question is that i want to parse the port along with the arguments, how do i do that? (Updated the question — Freon
– Freon, Commented Aug 16, 2016 at 10:25
"it gives me the wrong option" doesn't describe exactly what you're doing or what you're seeing. — Jon Skeet
– Jon Skeet, Commented Aug 16, 2016 at 10:27
@Sayse so you mean that i should start at 0? in the port parts? — Freon
– Freon, Commented Aug 16, 2016 at 10:31

Dmitrii Bychenko · Accepted Answer · 2016-08-16 11:09:19Z

1

It seems, that you want port being the last parameter:

  static void Main(string[] args) {  
    // if we have parameters...
    if (args.Length > 0) { 
      //TODO: int.TryParse is a better choice
      int port = int.Parse(args[args.Length - 1]); // ... port is the last one
      server = new TcpListener(IPAddress.Any, port);
      // Rest of the program
    }
  }

Edit: if you want to pass just two parameters (option and port)

  static void Main(string[] args) { 
    if (args.Length == 2) {
      //TODO: int.TryParse is a better choice 
      int option = int.Parse(args[0]);
      int port = int.Parse(args[1]);

      // Rest of the program, e.g.
      if (option == 1) {
        ...  
      } 
      else if (option == 2) {
        ...
      }
      else if (option == 3) {
        ...
      }   
    }
  }

edited Aug 16, 2016 at 11:09

answered Aug 16, 2016 at 10:46

Dmitrii Bychenko

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5 Comments

Freon Over a year ago

So that allows me to select the each configuration, so if i choose option one i would write "program 1 1234" 1 being the first config/option and 1234 being the last parameter for port.

Dmitrii Bychenko Over a year ago

@Freon: Yes, as far as I can see from your code, you're looking for something like that, with port being the last parameter

Freon Over a year ago

Because like before i had it via user input on console, so like if (option == "1"){//Rest of program} . Now i want to do the same but just passing the parameters. Anyway when i run your version it always gives me the first option, i cant choose option 2

Dmitrii Bychenko Over a year ago

@Freon: in this case, first read exactly two parameters (option and port) and then put the if on option value, not on args.Length; see my edit

Freon Over a year ago

Thanks, i realised i could still use if statements/switch statements

Tom Söhne · Accepted Answer · 2016-08-16 11:04:08Z

0

Is this, what you want?

class MainClass
{
    static void Main(string[] args)
    {
        // Test if input arguments were supplied:
        var switchvalue = int.Parse(args[0]);
        if (switchvalue == 1)
                {
            int port = int.Parse(args[1]);
            server = new TcpListener(IPAddress.Any, port);
            //Rest of the program
        }
        if (switchvalue == 2)
        {
            int port = int.Parse(args[1]);
            server = new TcpListener(IPAddress.Any, port);
            //Rest of the program
        }
        if (switchvalue == 3)
        {
            int port = int.Parse(args[1]);
            server = new TcpListener(IPAddress.Any, port);
            //Rest of the program
        }
    }
}

edited Aug 16, 2016 at 11:04

answered Aug 16, 2016 at 10:50

Tom Söhne

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2 Comments

Freon Over a year ago

Kind of like that but when i type "program 1 1234" it just hangs, no errors. When i run on Vstudio it gives me Index was outside the bounds of the array.

Freon Over a year ago

Ahh yeah forgot to change the args to 1. It works now. It was hard to explain what i was wanting but thank you. Didnt know that you can easily use a switch statement to pass as a arg[0]

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