[سعود]

السؤال الاول

كود :

 Function IsEmail(ByVal email As String) As Boolean
       Static emailExpression As New Regex("^[_a-z0-9-]+(.[a-z0-9-]+)@[a-z0-9-]+(.[a-z0-9-]+)*(.[a-z]{2,4})$")
       Return emailExpression.IsMatch(email)
   End Function

الثاني

كود :

 Function isnum(ByVal num As String) As Boolean
       Static numExpression As New Regex("^[0-9]*$")
       Return numExpression.IsMatch(num)
   End Function

الثالث

كود :

Function isletter(ByVal leter As String) As Boolean
       Static leterExpression As New Regex("^[a-z]{6,6}$", RegexOptions.IgnoreCase)
       Return leterExpression.IsMatch(leter)
   End Function