How to Add DropDownList during Runtime in C# or Dropdown in code behind

This is the code for Drop downlist when you have to add different data in dropdown during runtime.
where “Carbon” is the text value and “1″ is the Value

Code:

public void Button1_Click (object sender, System.EventArgs e) { this.ListBox1.Items.Add(new ListItem("Carbon", "1")); this.ListBox1.Items.Add(new ListItem("Oxygen", "2")); }