How to display alphabetically sorted data in Repeater

<asp:Repeater id='Repeater1' runat='server'>
<ItemTemplate >
	<b>
	<u><p>
	<%#GetFirstAlphabet(DataBinder.Eval(Container.DataItem, 'LastName').ToString())%>
	</p></u> 
</b>
<%#DataBinder.Eval(Container.DataItem, 'LastName').ToString()%>
,<%#DataBinder.Eval(Container.DataItem, 'FirstName').ToString()%><br>
</ItemTemplate>
</asp:Repeater>

VB.NET

If Not Page.IsPostBack Then
	’Populate the Data in the Repeater
End If

protected function GetFirstAlphabet(ByVal strval As String) As String
Dim alphabet As String = ViewState('alphabet')
If alphabet = Left(strval, 1) Then
	Return ''
Else
	alphabet = Left(strval, 1)
	ViewState('alphabet') = alphabet
	Return alphabet
End If
End Function

C#

if(!Page.IsPostBack)
{
	//Populate the Data in the Repeater		
}

protected string GetFirstAlphabet(string strval)
{
	string  alphabet   =(string) ViewState['alphabet'];
	if( alphabet == strval.Substring(0,1) )
	{
		return '';
	}
	else
	{
		alphabet = strval.Substring(0,1);
		ViewState['alphabet'] = alphabet;
		return alphabet;
	}
}