How to get string.Split() to recognize quoted string as a single entity?

Question

I was trying to write a console method to simulate command-line argument input, but I can't get string.Split() to recognize "fourth arg" as a single entity. For example, using the space character as the separator, if I entered a string like:
firstarg second-arg third:arg "fourth arg"
into an args[] using string.Split(), the args[] gets 5 strings instead of 4. It parses "fourth arg" into two strings:
\"fourth and arg\". A true command-line argument would treat "fourth arg" as a single entity
fourth arg. See code example below.

using System;
using static System.Console;

namespace Temp
{
    class Program
    {
        private static void Main ()
        {
            SimulateCommandLineArgs ();
            _ = ReadKey ();
        }

        private static void SimulateCommandLineArgs ()
        {
            string input;
            string [] args;

            Write ("Enter list of input items separated by spaces: ");

            input = ReadLine ();
            args = input.Split (' ', 20, StringSplitOptions.TrimEntries);

            WriteLine ($"There are {args.Length} arguments.");

        }

    }
}

Answer 1

Hello @Nicholas Piazza ,

I understand what you want want to achieve.

Using the string.split() is perhaps not the best solution...

Have you already checked out RegEx? There you can get an array of groups of characters...

I found this possible solution:

[^\s"']+|"([^"]*)"|'([^']*)'  

It turns your example in four groups:

Yes, there is a learning curve with RegEx but it's worth it!

The tester I used, even generated this code:

using System;
using System.Text.RegularExpressions;

public class Example
{
public static void Main()
{
string pattern = @"[^\s""']+|""([^""])""|'([^'])'";
string input = @"firstarg second-arg third:arg ""fourth arg""";
RegexOptions options = RegexOptions.Multiline;
foreach (Match m in Regex.Matches(input, pattern, options))
{
Console.WriteLine("'{0}' found at index {1}.", m.Value, m.Index);
}
}
}

Regards,

Sander

Answer 2

Perhaps one of the following would help.

• NuGet Gallery | Microsoft.Extensions.CommandLineUtils 1.1.1
• NuGet Gallery | CommandLineParser 2.8.0

Also see .NET - Parse the Command Line with System.CommandLine | Microsoft Learn.