The documentation for the CommandLineParser Nuget package at https://commandline.codeplex.com/ is out-of-date. Below is an updated working example of command line parsing, including displaying parsing errors
using System;
using System.Collections.Generic;
using CommandLine;
using CommandLine.Text;
namespace CmdLineParser
{
class Options
{
[Option('i', "input", Required = true, HelpText = "Input file to read.")]
public string InputFile { get; set; }
[Option('l', "length", DefaultValue = -1, HelpText = "The maximum number of bytes to process.")]
public int MaximumLength { get; set; }
[Option('v', null, HelpText = "Print details during execution.")]
public bool Verbose { get; set; }
[ValueList(typeof(List<string>), MaximumElements = 2)]
public IList<string> Items { get; set; }
[HelpOption]
public string GetUsage()
{
return HelpText.AutoBuild(this, (HelpText current) =>
HelpText.DefaultParsingErrorsHandler(this, current));
}
[ParserState]
public IParserState LastParserState { get; set; }
}
class Program
{
static void Main(string[] args)
{
var options = new Options();
var parser = new CommandLine.Parser();
var result = parser.ParseArguments(args, options);
if (result)
{
if (options.Verbose)
{
Console.WriteLine(options.InputFile);
Console.WriteLine(options.MaximumLength);
}
else
Console.WriteLine("working ...");
}
else
{
Console.WriteLine(options.GetUsage());
}
Console.WriteLine("Press any key to continue...");
Console.ReadKey();
}
}
}