using System;
using System.Text.RegularExpressions;
 
public class Test
{
	public static void Main()
	{
            var pattern = @"^(?=\d+[a-z]+(?:-\d+[a-z]+)*$)(?>(?<gal>\d+)gal-?)?(?>(?<qt>\d)+qt-?)?(?>(?<pt>\d+)pt-?)?(?>(?<cup>\d+)cup-?)?(?>(?<oz>\d+)oz-?)?$";        
            string[] strings = {"1gal-1qt-2pt-2cup-5oz", "1gal-6oz", "1gal"};
            foreach (string s in strings) {
                var regex = new Regex(pattern);
                GroupCollection groups = regex.Match(s).Groups;
 
                foreach (string groupName in regex.GetGroupNames())
                {
                    Console.WriteLine("Group: {0}, Value: {1}", groupName, groups[groupName].Value);
 
                }
                Console.WriteLine("====================================");
            }
	}
}
 

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