C#

using Microsoft.VisualBasic;
using System;
using System.Collections;
using System.Collections.Generic;
using System.Data;
using System.Diagnostics;
using System.Runtime.InteropServices;

public class Form1
{

	private void Form1_Load(System.Object sender, System.EventArgs e)
	{
		CueBannerText.SetCueText(TextBox1, "Enter Name here");
	}
	public Form1()
	{
		Load += Form1_Load;
	}
}



public static class CueBannerText
{
	[DllImport("user32.dll", CharSet = CharSet.Auto)]
	private static Int32 SendMessage(IntPtr hWnd, int msg, int wParam, 	[MarshalAs(UnmanagedType.LPWStr)]
string lParam)
	{
	}
	[DllImport("user32", EntryPoint = "FindWindowExA", CharSet = CharSet.Ansi, SetLastError = true, ExactSpelling = true)]
	private static extern IntPtr FindWindowEx(IntPtr hWnd1, IntPtr hWnd2, string lpsz1, string lpsz2);

	private const int EM_SETCUEBANNER = 0x1501;

	public static void SetCueText(Control cntrl, string text)
	{
		if (cntrl is ComboBox) {
			IntPtr Edit_hWnd = FindWindowEx(cntrl.Handle, IntPtr.Zero, "Edit", null);
			if (!(Edit_hWnd == IntPtr.Zero)) {
				SendMessage(Edit_hWnd, EM_SETCUEBANNER, 1, text);
			}
		} else if (cntrl is TextBox) {
			SendMessage(cntrl.Handle, EM_SETCUEBANNER, 1, text);
		}
	}
}

string strQuery= @"SELECT myID,myItem FROM Table1 WHERE IdCountry=1";
SqlConnection cnnCbx = new SqlConnection(cnnClass.CnnString);
cnnCbx.Open();
SqlDataAdapter daCbx = new SqlDataAdapter(strCbxQueryItems, cnnCbx);
DataTable dtCbx = new DataTable();
daCbx.Fill(dtCbx);
cbxKindOfItems.ValueMember = "myID";
cbxKindOfItems.DisplayMember = "myItem";
cbxKindOfItems.DataSource = dtCbx.DefaultView;

public double Percentile(double[] sequence, double excelPercentile)
        {
            Array.Sort(sequence);
            int N = sequence.Length;
            double n = (N - 1) * excelPercentile + 1;
            // Another method: double n = (N + 1) * excelPercentile;
            if (n == 1d) return sequence[0];
            else if (n == N) return sequence[N - 1];
            else
            {
                int k = (int)n;
                double d = n - k;
                return sequence[k - 1] + d * (sequence[k] - sequence[k - 1]);
            }
        }