Use Plossum CommandLine to parse and verify DateTime

CommandLineOptions.cs

using System;
using Plossum.CommandLine;

namespace ConsoleApp
{
    [CommandLineManager(ApplicationName = "ProgramName", Copyright = "Copyright (c) Bobby Chopra")]
    internal class CommandLineOptions
    {
        private string _date;


        [CommandLineOption(Description = "Displays this help text")]
        public bool Help = false;

        [CommandLineOption(Description = "Specifies the Date for the Child Pages", MinOccurs = 1)]
        public string Date
        {
            get { return _date; }
            set
            {
                DateTime dateAsArg;

                if (!DateTime.TryParse(value, out dateAsArg))
                    throw new InvalidOptionValueException("The argument is not a date", false);

                if (dateAsArg < DateTime.Today.AddMonths(-6) || dateAsArg > DateTime.Today.AddMonths(1))
                    throw new InvalidOptionValueException( "The date is too far away", false);

                _date = dateAsArg.ToString("MM/dd/yyyy");
            }
        }
    }
}

Program.cs

using System;
using Plossum.CommandLine;

namespace ConsoleApp
{
    internal class Program
    {
        private static int Main(string[] args)
        {
            var options = new CommandLineOptions();
            var parser = new CommandLineParser(options);
            parser.Parse();
            Console.WriteLine(parser.UsageInfo.GetHeaderAsString(78)); // 78 is the screen width

            if (options.Help)
            {
                Console.WriteLine(parser.UsageInfo.GetOptionsAsString(78));
                return 0;
            }
            else if (parser.HasErrors)
            {
                Console.WriteLine(parser.UsageInfo.GetErrorsAsString(78));
                return -1;
            }

            //get date
            var date = options.Date;
            // ... continue
            return 0;
        }
    }
}