Best way to parse command line arguments in C#?

Question

When building console applications that take parameters, you can use the arguments passed to Main(string[] args).

In the past I've simply indexed/looped that array and done a few regular expressions to extract the values. However, when the commands get more complicated, the parsing can get pretty ugly.

So I'm interested in:

• Libraries that you use
• Patterns that you use

Assume the commands always adhere to common standards such as answered here.

Solution 1

I would strongly suggest using NDesk.Options (Documentation) and/or Mono.Options (same API, different namespace). An example from the documentation:

bool show_help = false;
List<string> names = new List<string> ();
int repeat = 1;

var p = new OptionSet () {
    { "n|name=", "the {NAME} of someone to greet.",
       v => names.Add (v) },
    { "r|repeat=", 
       "the number of {TIMES} to repeat the greeting.\n" + 
          "this must be an integer.",
        (int v) => repeat = v },
    { "v", "increase debug message verbosity",
       v => { if (v != null) ++verbosity; } },
    { "h|help",  "show this message and exit", 
       v => show_help = v != null },
};

List<string> extra;
try {
    extra = p.Parse (args);
}
catch (OptionException e) {
    Console.Write ("greet: ");
    Console.WriteLine (e.Message);
    Console.WriteLine ("Try `greet --help' for more information.");
    return;
}

Solution 2

I really like the Command Line Parser Library ( http://commandline.codeplex.com/ ). It has a very simple and elegant way of setting up parameters via attributes:

class Options
{
    [Option("i", "input", Required = true, HelpText = "Input file to read.")]
    public string InputFile { get; set; }

    [Option(null, "length", HelpText = "The maximum number of bytes to process.")]
    public int MaximumLenght { get; set; }

    [Option("v", null, HelpText = "Print details during execution.")]
    public bool Verbose { get; set; }

    [HelpOption(HelpText = "Display this help screen.")]
    public string GetUsage()
    {
        var usage = new StringBuilder();
        usage.AppendLine("Quickstart Application 1.0");
        usage.AppendLine("Read user manual for usage instructions...");
        return usage.ToString();
    }
}

Solution 3

The WPF TestApi library comes with one of the nicest command line parsers for C# development. I highly recommend looking into it, from Ivo Manolov's blog on the API:

// EXAMPLE #2:
// Sample for parsing the following command-line:
// Test.exe /verbose /runId=10
// This sample declares a class in which the strongly-
// typed arguments are populated
public class CommandLineArguments
{
   bool? Verbose { get; set; }
   int? RunId { get; set; }
}

CommandLineArguments a = new CommandLineArguments();
CommandLineParser.ParseArguments(args, a);

Solution 4

Look at http://github.com/mono/mono/tree/master/mcs/class/Mono.Options/

Solution 5

Looks like everybody has their own pet command-line parsers, figure I had better add mine as well :).

http://bizark.codeplex.com/

This library contains a command-line parser that will initialize a class with the values from the command-line. It has a ton of features (I've been building it up over many years).

From the documentation...

Command-line parsing in the BizArk framework has these key features:

• Automatic initialization: Class properties are automatically set based on the command-line arguments.
• Default properties: Send in a value without specifying the property name.
• Value conversion: Uses the powerful ConvertEx class also included in BizArk to convert values to the proper type.
• Boolean flags: Flags can be specified by simply using the argument (ex, /b for true and /b- for false) or by adding the value true/false, yes/no, etc.
• Argument arrays: Simply add multiple values after the command-line name to set a property that is defined as an array. Ex, /x 1 2 3 will populate x with the array { 1, 2, 3 } (assuming x is defined as an array of integers).
• Command-line aliases: A property can support multiple command-line aliases for it. For example, Help uses the alias ?.
• Partial name recognition: You don’t need to spell out the full name or alias, just spell enough for the parser to disambiguate the property/alias from the others.
• Supports ClickOnce: Can initialize properties even when they are specified as the query string in a URL for ClickOnce deployed applications. The command-line initialization method will detect if it is running as ClickOnce or not so your code doesn’t need to change when using it.
• Automatically creates /? help: This includes nice formatting that takes into account the width of the console.
• Load/Save command-line arguments to a file: This is especially useful if you have multiple large, complex sets of command-line arguments that you want to run multiple times.

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