try this it is confirm code:
1. First add java script to head section
<script type="text/javascript">
function checkDate(sender, args) {
if (sender._selectedDate < new Date()) {
alert("You cannot select a day earlier than today!");
sender._selectedDate = new Date();
// set the date back to the current date
sender._textbox.set_Value(sender._selectedDate.format(sender._format))
}
}
</script>
2.then call it into date picker like this:
<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
<asp:CalendarExtender ID="TextBox1_CalendarExtender" OnClientDateSelectionChanged="checkDate" runat="server"
TargetControlID="TextBox1">
</asp:CalendarExtender>
</form>
Its End:
I Also put all page code for better understating for you:
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="testFinal.aspx.cs" Inherits="ArunHome_Design_testFinal" %>
<%@ Register assembly="AjaxControlToolkit" namespace="AjaxControlToolkit" tagprefix="asp" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<script type="text/javascript">
function checkDate(sender, args) {
if (sender._selectedDate < new Date()) {
alert("You cannot select a day earlier than today!");
sender._selectedDate = new Date();
sender._textbox.set_Value(sender._selectedDate.format(sender._format))
}
}
</script>
</head>
<body>
<form id="form1" runat="server">
<%----%>
<asp:ToolkitScriptManager ID="ToolkitScriptManager1" runat="server">
</asp:ToolkitScriptManager>
<br />
<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
<asp:CalendarExtender ID="TextBox1_CalendarExtender" OnClientDateSelectionChanged="checkDate" runat="server"
TargetControlID="TextBox1">
</asp:CalendarExtender>
</form>
</body>
</html>