为什么 "If Value is Nothing" 抛出 "Object Required (Error 424)"

Question

以下代码在 if 语句中抛出 Object Required (Error 424) 与 Nothing 相比，与给定的值无关。为什么？

Public Function SqlizeCellValue(ByVal Value As Variant) As Variant
    If Value Is Nothing Then
        SqlizeCellValue = Nothing
    ElseIf Value = Null Then
        SqlizeCellValue = Null
    ElseIf Value = "" Then
        SqlizeCellValue = Null
    ElseIf Value = "0" Then
        SqlizeCellValue = Null
    ElseIf Value = "---" Then
        SqlizeCellValue = Null
    ElseIf LCase(Value) = "n.c." Then
        SqlizeCellValue = Null
    Else
        SqlizeCellValue = Value
    End If
End Function
Public Sub TestSqlizeCellValue()
    Debug.Assert SqlizeCellValue("") Is Null
    Debug.Assert SqlizeCellValue("0") Is Null
    Debug.Assert SqlizeCellValue("---") Is Null
    Debug.Assert SqlizeCellValue(Nothing) Is Nothing
    Debug.Assert SqlizeCellValue(Null) Is Null
End Sub

Answer 1

因为你的函数定义中的Value设置为类型Variant，只有一个Object可以是Set到Nothing

为什么 "If Value is Nothing" 抛出 "Object Required (Error 424)"

Why does "If Value is Nothing" throw "Object Required (Error 424)"

vba

if-statement

nothing