' The user is asked to enter a 5-character string. If the
' length of the entry is not 5, the result of Exit Function is
' to return the empty string and issue a message telling you
' the entry is invalid.
Function AssignCode As String
Dim code As String
code$ = InputBox("Enter a 5-character code")
If Len(code$) <> 5 Then Exit Function
AssignCode = code$ ' It is a valid code.
End Function
If AssignCode() <> "" Then
MessageBox "You entered a valid code."
Else
MessageBox "The code you entered is not valid."
End If