vba 为什么 If Not IsEmpty 不过滤掉空字符串？
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Why doesn't If Not IsEmpty filter out empty strings?
提问by Kyle
What is wrong with my Ifcondition?
我的If病情有什么问题？
If Not IsEmpty(Wrkgps_L3) And Not IsEmpty(Wrkgps_L4) Then
Wrkgps_L3L4 = Wrkgps_L3 & "," & Wrkgps_L4
End If
The Notcondition doesn't seem to work. The code within the Ifstatement gets executed even when both Wrkgps_L3and Wrkgps_L4are empty strings.
该Not条件似乎不起作用。If即使Wrkgps_L3和Wrkgps_L4都是空字符串，语句中的代码也会被执行。
Update:
更新：
Wrkgps_L3and Wrkgps_L4are variables that contain results returned from a function. I noticed that IsEmpty(Wrkgps_L3) = Falseeven though Wrkgps_L3 = "". I had to rewrite my code to
Wrkgps_L3和Wrkgps_L4是包含从函数返回的结果的变量。我注意到IsEmpty(Wrkgps_L3) = False即使Wrkgps_L3 = "". 我不得不重写我的代码
If (Wrkgps_L3 <> "") And (Wrkgps_L4 <> "") Then
In any case, I am still intrigued to know why IsEmptydoesn't work on variables with ""?
无论如何，我仍然很想知道为什么IsEmpty不能使用""?
回答by Michael Liu
In Visual Basic, Emptyand ""(an empty string) are two different things. Emptyis the uninitialized state of a Variantvariable, and IsEmptytests whether a Variantvariable has the Emptyvalue:
在 Visual Basic 中，Empty和""（空字符串）是两个不同的东西。Empty是Variant变量的未初始化状态，并IsEmpty测试Variant变量是否具有Empty值：
Dim x As Variant
If IsEmpty(x) Then
Debug.Print "x is empty"
End If
As you've observed, you must compare against ""when checking whether a Stringvariable contains an empty string.
正如您所观察到的，您必须""在检查String变量是否包含空字符串时进行比较。
回答by Steve Rindsberg
If the variables are strings, you could also:
如果变量是字符串，您还可以：
If Len(Wrkgps_L3) + Len(Wrkgps_L4) = 0 Then
' They're both empty string variables
Else
' One or the other contains at least one character
End If
