[vb6] InputBox is OK or Cancel?

You display an InputBox. But did the user press Cancel - or OK without entering anything? If you thought there was no way to tell the difference, you're wrong.

You see, if the user presses cancel, vbNullString is returned. However if they press OK, the empty string ("") is sent back. But in Visual Basic, vbNullString equates to an empty string, so you can't compare the two - even though in reality, they're completely different.

However you can use the StrPtr ('string pointer') function to determine whether the return string is indeed a vbNullString - as by definition, a vbNullString 'pointer' is zero.

Private Sub Form_Load()
  Dim strInput

  strInput = InputBox("Enter something:")

  If StrPtr(strInput) = 0 Then
    MsgBox "You pressed Cancel button!"
  ElseIf strInput = "" Then
    MsgBox "You press OK button with blank value!"
  End If
  End
End Sub