Parsing command-line options in C#

Question

I've seen people write custom classes to more easily handle command line options in various languages. I wondered if .NET (3.5 or lower) has anything built in so that you don't have to custom-parse things like:

myapp.exe file=text.txt

Answer 1

For quick-and-dirty utilities where you don't need anything sophisticated, many times a console application takes command lines of the form:

program.exe command -option1 optionparameter option2 optionparameter

etc.

When that's the case, to get the 'command', just use args[0]

To get an option, use something like this:

var outputFile = GetArgument(args, "-o");

Where GetArgument is defined as:

string GetArgument(IEnumerable<string> args, string option)
    => args.SkipWhile(i => i != option).Skip(1).Take(1).FirstOrDefault();

Answer 2

Here is another possible approach. Very simple but it has worked for me in the past.

string[] args = {"/a:b", "/c:", "/d"};
Dictionary<string, string> retval = args.ToDictionary(
     k => k.Split(new char[] { ':' }, 2)[0].ToLower(),
     v => v.Split(new char[] { ':' }, 2).Count() > 1 
                                        ? v.Split(new char[] { ':' }, 2)[1] 
                                        : null);

Answer 3

If you don't like to use a library and something simple is good enough you could do this:

string[] args = Environment.GetCommandLineArgs().Skip(1).ToArray();
Func<string, string> lookupFunc = 
    option => args.Where(s => s.StartsWith(option)).Select(s => s.Substring(option.Length)).FirstOrDefault();

string myOption = lookupFunc("myOption=");

;

Answer 4

Edit: No.

But there are parsers that people have built such as...

Arguably the best out there: C# Command Line Argument Parser

Answer 5

This is a fairly old post, but here's something I devised and use in all of my console applications. It's just a small snippet of code that can be injected into a single file and everything will work.

http://www.ananthonline.net/blog/dotnet/parsing-command-line-arguments-with-c-linq

Edit: This is now available on Nuget, and is part of the open-source project CodeBlocks.

It was devised to be declaratively and intuitively used, like so (another usage example here):

args.Process(
    // Usage here, called when no switches are found
    () => Console.WriteLine("Usage is switch0:value switch:value switch2"),

    // Declare switches and handlers here
    // handlers can access fields from the enclosing class, so they can set up
    // any state they need.
    new CommandLine.Switch(
        "switch0",
        val => Console.WriteLine("switch 0 with value {0}", string.Join(" ", val))),
    new CommandLine.Switch(
        "switch1",
        val => Console.WriteLine("switch 1 with value {0}", string.Join(" ", val)), "s1"),
    new CommandLine.Switch(
        "switch2",
        val => Console.WriteLine("switch 2 with value {0}", string.Join(" ", val))));