如何在VBA中評估Or語句？

Question

我只是想知道Or條件語句在VBA / VB6中是如何工作的。 基本上，如果我們有If A Or B Then ，布爾表達式的評估順序是什么？ 如果A為真，B還會被評估嗎？

Answer 1

以下是一些測試結果：

Public Sub DoTesting()

    ' Displays "Test1" followed by "Test2", so they're evaluated in order.
    ' Also, both expressions are evaluated even though Test1() is False.
    If Test1() And Test2() Then
    End If

    ' Displays "Test2" followed by "Test1", so they're evaluated in order.
    ' Also, both expressions are evaluated even though Test2() is True.
    If Test2() Or Test1() Then
    End If

    ' Displays "Test1" only. Test2() is not evaluated.
    If Test1() Then If Test2() Then Debug.Print ""

End Sub

Public Function Test1() As Boolean
    MsgBox "Test1"
    Test1 = False
End Function

Public Function Test2() As Boolean
    MsgBox "Test2"
    Test2 = True
End Function

因此，在這兩個表達式Or或And一直被運用，為了不分勝負。 您可以使用If ... Then If ... Then實現簡單的內聯短路。