How to add a blank item at the top of DropDownList in dropdownlist add blank item
DropDownList is an web server control. this is a list web server control. dropdownlist control allow us to select a single item from a drop-down-list. generally dropdownlist items contain item text and value. sometime we need to create blank item (item with no visible text) and add it to dropdownlist programmatically.

dropdownlist visible area always display an item that can be first item or selected item. when page loaded, we can display a blank item in dropdownlist by putting the item at first position. to do this programmatically, we need to create a new list item and set its text and value to empty string. after creating the item we will insert it to dropdownlist items collection at index 0. finally the dropdownlist will display a blank item at items first position.

the first blank item also very useful when we want to use dropdownlist SelectedIndexChanged event effectively. then it will allow us to fire SelectedIndexChanged event by selecting first item with text (actually second item because first item is blank).

the following c# example code demonstrate us how can we create and display a blank item in dropdownlist top position in an application.

<%@ Page Language="C#" AutoEventWireup="true"%>  
<!DOCTYPE html>
<script runat="server">
    protected void Page_Load(object sender, EventArgs e)
        if (!Page.IsPostBack)
            string[] birds = { "Fairy Prion", "Antarctic Prion", "Cahow", "Cape Petrel" };
            DropDownList1.DataSource = birds;

            //this line create a new list item.
            ListItem li = new ListItem();
            li.Text = string.Empty;
            li.Value = string.Empty;

            //this line add a blank list item dynamically at list top.
            DropDownList1.Items.Insert(0, li);
<html xmlns="">      
<head id="Head1" runat="server">      
    <title> dropdownlist add blank item</title>
    <form id="form1" runat="server">      
        <h2 style="color:MidnightBlue; font-style:italic;">      
   example - dropdownlist add blank item
        <hr width="550" align="left" color="Gainsboro" />      
        <br /><br />
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