How to add empty alternative to dropDownList

Question

I am populating a dropdownlist using the following code:

SPList categories = SPContext.Current.Web.Lists["Categories"];
                dropdownlist.DataSource = categories.Items;
                dropdownlist.DataValueField = "ID";
                dropdownlist.DataTextField = "Title";
                dropdownlist.DataBind();

I need to change the code so that if the user do not want to select any value from dropdownlist he will be able to to select an empty option. How can I add an empty alternative to the dropdown so to make a selection not required?

Answer 1

SPList categories = SPContext.Current.Web.Lists["Categories"];
                dropdownlist.DataSource = categories.Items;
                dropdownlist.DataValueField = "ID";
                dropdownlist.DataTextField = "Title";
                dropdownlist.DataBind();

// Add this after DataBind()

dropdownlist.items.Insert(0, new ListItem("",""));