<%@ Page Language="C#" %>
<script language="JavaScript">
function MultipleOfFive_Clnt( source, args) {
if( args.Value % 5 == 0 )
args.IsValid = true;
else
args.IsValid = false;
}
</script>
<script language="C#" runat="server">
void MultipleOfFive_Svr(object source, ServerValidateEventArgs e) {
e.IsValid = false;
int num;
if ( Int32.TryParse( e.Value, out num ) )
if ( num % 5 == 0 )
e.IsValid = true;
}
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<body>
<form id="Form1" action="Default.aspx" method="post" runat="server">
<asp:Button ID="MyButton" runat="server" Text="Submit" />
<asp:TextBox ID="MyTextBox" runat="server" />
<asp:CustomValidator
ID="MyCustomValidator" runat="server"
ControlToValidate="MyTextBox"
ClientValidationFunction="MultipleOfFive_Clnt"
OnServerValidate="MultipleOfFive_Svr"
ErrorMessage="Must be a multiple of 5!"
ValidateEmptyText="False" />
</form>
</body>
</html>