Asp form verification function

'*************************************
'Check whether only English and numbers are included
'*************************************

Function IsvalidValue (ArrayN, Str)
IsvalidValue = False
Dim GName
For Each GName in ArrayN
If Str = GName Then
IsvalidValue = True
Exit
End If
Next
End Function

'*************************************
'Check for valid digits
'*************************************

Function IsInteger (Para)
IsInteger = False
If Not (IsNull (Para) Or Trim (Para) = "Or Not IsNumeric (Para) Then
IsInteger = True
End If
End Function

'*************************************
'User name Detection
'*************************************

Function IsValidUserName (byVal UserName)
Dim I, c
Dim VUserName
IsValidUserName = True
For I = 1 To Len (UserName)
C = LCase (Mid (UserName, I, 1 ))
If InStr ("$! <>? # ^ % @~ '& * ();: + =' "", C)> 0 Then
IsValidUserName = False
Exit Function
End If
Next
For Each VUserName in Register_UserName
If UserName = VUserName Then
IsValidUserName = False
Exit
End If
Next
End Function

'*************************************
'Check whether the email address is valid
'*************************************

Function IsValidEmail (Email)
Dim names, Name, I, c
IsValidEmail = True
Names = Split (email ,"@")
If UBound (names) <> 1 Then
IsValidEmail = False
Exit Function
End If
For Each Name IN names
If Len (Name) <= 0 Then
IsValidEmail = False
Exit Function
End If
For I = 1 To Len (Name)
C = LCase (Mid (Name, I, 1 ))
If InStr ("abcdefghijklmnopqrstuvwxyz _-.", c) <= 0 And Not IsNumeric (c) Then
IsValidEmail = False
Exit Function
End If
Next
If Left (Name, 1) = "." Or Right (Name, 1) = "." Then
IsValidEmail = False
Exit Function
End If
Next
If InStr (names (1), ".") <= 0 Then
IsValidEmail = False
Exit Function
End If
I = Len (names (1)-faster Rev (names (1 ),".")
If I <> 2 And I <> 3 Then
IsValidEmail = False
Exit Function
End If
If InStr (email, "...")> 0 Then
IsValidEmail = False
End If
End Function