Gets the value associated with the specified input control.
Assembly: System.Web (in System.Web.dll)
Use the method to get the value associated with the specified input control, regardless of the control type. For example, you can use this method to get the value in a TextBox control, as well as the value of the selected item from a ListBox control. If the specified control cannot be found, null is returned.
This method is used primarily by control developers.