CommandLineHelper.cs

    public class CommandLineHelper
    {
        /// <summary>
        /// Get value from command line
        /// </summary>
        /// <remarks>
        /// Example:
        ///   GetCommandLineValue(args, "--START", out _startDate, DateTime.MinValue);
        /// </remarks>
        /// <param name="args"></param>
        /// <param name="key"></param>
        /// <param name="value"></param>
        /// <param name="defaultValue"></param>
        /// <returns></returns>
        public static bool GetValue<T>(IReadOnlyList<string> args, string key, out T value, T defaultValue)
        {
            return GetValue(args, new List<string>() { key }, out value, defaultValue);
        }

        /// <summary>
        /// Get value from command line
        /// </summary>
        /// <remarks>
        /// Example:
        ///   GetCommandLineValue(args, {"-s", "--START"}, out _startDate, DateTime.MinValue);
        /// </remarks>
        /// <typeparam name="T"></typeparam>
        /// <param name="args"></param>
        /// <param name="keys"></param>
        /// <param name="value"></param>
        /// <param name="defaultValue"></param>
        /// <returns></returns>
        public static bool GetValue<T>(IReadOnlyList<string> args, List<string> keys, out T value, T defaultValue)
        {
            foreach (var key in keys)
            {
                for (var i = 0; i < args.Count; i++)
                {
                    if (args[i].Equals(key, StringComparison.OrdinalIgnoreCase))
                    {
                        //get the text
                        string text;
                        if (typeof(T) == typeof(bool))
                        {
                            text = "true";
                        }
                        else if (i + 1 < args.Count)
                        {
                            text = args[i + 1];
                        }
                        else
                        {
                            continue;
                        }
                        //convert text to value's type
                        var tc = System.ComponentModel.TypeDescriptor.GetConverter(typeof(T));
                        value = (T)tc.ConvertFromString(null, CultureInfo.InvariantCulture, text);
                        return true;
                    }
                }
            }
            value = defaultValue;
            return false;
        }

        /// <summary>
        /// Get value from command line
        /// </summary>
        /// <remarks>
        /// Example:
        ///   GetCommandLineValue(args, "--START", out _startDate, DateTime.MinValue);
        /// </remarks>
        /// <param name="args"></param>
        /// <param name="key"></param>
        /// <param name="defaultValue"></param>
        /// <returns></returns>
        public static T GetValue<T>(IReadOnlyList<string> args, string key, T defaultValue)
        {
            return GetValue(args, new List<string>() { key }, defaultValue);
        }


        /// <summary>
        /// Get value from command line
        /// </summary>
        /// <remarks>
        /// Example:
        ///   GetCommandLineValue(args, {"-s", "--START"}, out _startDate, DateTime.MinValue);
        /// </remarks>
        /// <typeparam name="T"></typeparam>
        /// <param name="args"></param>
        /// <param name="keys"></param>
        /// <param name="defaultValue"></param>
        /// <returns></returns>
        public static T GetValue<T>(IReadOnlyList<string> args, List<string> keys, T defaultValue)
        {
            foreach (var key in keys)
            {
                for (var i = 0; i < args.Count; i++)
                {
                    if (args[i].Equals(key, StringComparison.OrdinalIgnoreCase))
                    {
                        //get the text
                        string text;
                        if (typeof(T) == typeof(bool))
                        {
                            text = "true";
                        }
                        else if (i + 1 < args.Count)
                        {
                            text = args[i + 1];
                        }
                        else
                        {
                            continue;
                        }
                        //convert text to value's type
                        var tc = System.ComponentModel.TypeDescriptor.GetConverter(typeof(T));
                        var value = (T)tc.ConvertFromString(null, CultureInfo.InvariantCulture, text);
                        return value;
                    }
                }
            }
            return defaultValue;
        }


        /// <summary>
        /// Check common cries for help
        /// </summary>
        /// <remarks>
        /// ?, /?, -?, -help, --help
        /// </remarks>
        /// <param name="args"></param>
        /// <returns></returns>
        public static bool ShowHelp(IReadOnlyList<string> args)
        {
            if (
                args.Contains("?") ||
                args.Contains("--HELP", StringComparer.InvariantCultureIgnoreCase) ||
                args.Contains("-HELP", StringComparer.InvariantCultureIgnoreCase) ||
                args.Contains("/?") ||
                args.Contains("-?")
                )
            {
                return true;
            }

            return false;
        }

    }