Add a Tree Menu to DataGrid Header Text

using System;

namespace DataGridWithTreeMesu
{
	/// <summary>
	/// Summary description for DateTime.
	/// </summary>
	public class MyDateTime
	{
		public MyDateTime()
		{
			//
			// TODO: Add constructor logic here
			//
		}

		/// <summary>
		/// JulianToGregorian
		/// </summary>
		/// <PARAM name="strGregDate">string</PARAM>
		/// <PARAM name="strFormat">string</PARAM>
		public string JulianToGregorian(string strGregDate, string strFormat)
		{
			DateTime dtStart; 
			DateTime dtTrms;	 
			int iDays;	 
			int iYear;	 		 
			string strDate;
			int iPos;
			Array arParams = null;
			 
			strFormat = strFormat.ToUpper();
			arParams = strGregDate.Split('.');
			iYear = Convert.ToInt32((arParams.GetValue(0)).ToString());
			iDays = Convert.ToInt32((arParams.GetValue(1)).ToString());
			dtStart = new DateTime(iYear, 1, 1);
			dtTrms = dtStart.AddDays(iDays - 1);
			strDate = dtTrms.ToString();
			iPos = strDate.IndexOf(' ');
			strDate = strDate.Substring(0, iPos);

			strDate = ChangeDateFormat(strDate, strFormat);
			return strDate;
		}

		/// <summary>
		/// ChangeDateFormat
		/// </summary>
		/// <PARAM name="strDate">string</PARAM>
		/// <PARAM name="strFormat">string</PARAM>
		public string ChangeDateFormat(string strDate, string strFormat)
		{
			DateTime dateToInsert;
		 
			try
			{
				dateToInsert = DateTime.Parse(strDate);
			}
			catch
			{
				dateToInsert = DateTime.MinValue;
			}

			strFormat = strFormat.ToUpper();
			if(strFormat.StartsWith("MM") && strFormat.IndexOf("YYYY") != -1)
				strDate = dateToInsert.ToString("MM/dd/yyyy");
			else
				if(strFormat.StartsWith("MM") && strFormat.IndexOf("YY") != -1)
				strDate = dateToInsert.ToString("MM/dd/yy");
			else
				if(strFormat.StartsWith("DD") && strFormat.IndexOf("YYYY") != -1)
				strDate = dateToInsert.ToString("dd/MM/yyyy");
			else
				if(strFormat.StartsWith("DD") && strFormat.IndexOf("YY") != -1)
				strDate = dateToInsert.ToString("dd/MM/yy");

			return strDate;
		}


	}
}