Hi,

I have to validate TextBox.
I have a customValidate control for textbox.  I have following function for
customValidate control.

but if I type in textbox bobby
It throws exception that index shouldnot be less than zero
but if I type bobby@yahoo.com(bobby gill).  It works.  I want that if I if I
type bobby the validation control gives me error that it is not valid

public void ValidateUserID(object sender, ServerValidateEventArgs args)
   {
       CustomValidator valDate = sender as CustomValidator;
       args.IsValid = true;
       string str = args.Value;
       //string str = this.txtAddUsers.Text;
       string subStr1 = str.Substring(0, str.IndexOf("( "));
       bool isValidEmail = IsValidEmail(subStr1);
     
     
       if (isValidEmail == true)
       {
           args.IsValid = true;
       }
       else
       {
           args.IsValid = false;
           valDate.ErrorMessage = "Email is Invalid!";
           return;  
       }
       
   }
 public static bool IsValidEmail(string EmailAddress)
       {
           // Return true if strIn is in valid e-mail format.
           return Regex.IsMatch(EmailAddress,
@"^([\w-\.]+)@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.)|(([\w-]+\.)+))([a-zA-Z]{2,4}|[0-9]{1,3})(\]?)$");