(a)
NavigateUrlField="MessageID"; NavigateUrlFormatString="MessageDetails.aspx? MessageID= {0}";(b)
node.NavigateUrl = String.Format(NavigateUrlFormatString, (DataBinder.Eval(iter.Current, navigateUrlField)).ToString());(c)
node.NavigateUrl = "Post.aspx?MessageID=1";
Example 3: Evaluating expressions.