// @nuget: CommandLineParser -Version 2.6.0

​

using System;

using System.Collections.Generic;

using CommandLine;

​

using System.Linq;

​

public class Program

{

    public static void Main()

    {

         //var args ="-a xyz vv".Split(); //cause MissingRequiredOptionError

          string[] args ="vv -a xyz".Split();

         var result=    Parser.Default.ParseArguments<Options>(args);

        Console.WriteLine(result.Tag);

        result.WithParsed<Options>( o => { Console.WriteLine("A.count={0} | C={2}",o.A.Count() ,o.B,o.C); })

              .WithNotParsed(errs => HandleParseError(errs));

    }

    static void HandleParseError(IEnumerable<Error> errs)

     {

       errs.Dump();

     }

}

​

class Options

{

[Option('a', "aa", Required = false, Separator = ',')]

public IEnumerable<string> A { get; set; }

[Option('b', "bb", Required = false)]

public string B { get; set; }

[Value(0, Required = true)]

public string C { get; set; }

}

​