vba - 检查空数组

vba - checking for empty array

提问by TPR

Function IsVarArrayEmpty(anArray As Variant)

Dim i As Integer

On Error Resume Next
    i = UBound(anArray, 1)
If Err.Number = 0 Then
    IsVarArrayEmpty = False
Else
    IsVarArrayEmpty = True
End If

End Function

It is returning true for uninitialized and false for initialized. I want to see if it has any data/content. However, the problem is I feel the above code is returning false even when there is no data in the array. How do I check that?

它为未初始化返回真，为初始化返回假。我想看看它是否有任何数据/内容。但是，问题是我觉得即使数组中没有数据，上面的代码也会返回 false。我如何检查？

(I tried setting string s equal to the byte array. That was "". That means the array is empty, right?)

（我尝试将 string s 设置为等于字节数组。那是“”。这意味着数组是空的，对吧？）

回答by assylias

I personally use this - now if you ReDiman array with ReDim v (1 To 5) As Variant, isArrayEmpty(v)will return false because vhas 5 items, although they are all uninitialised.

我个人使用这个 - 现在如果你ReDim的数组带有ReDim v (1 To 5) As Variant,isArrayEmpty(v)将返回 false 因为v有 5 个项目，尽管它们都未初始化。

Public Function isArrayEmpty(parArray As Variant) As Boolean
'Returns true if:
'  - parArray is not an array
'  - parArray is a dynamic array that has not been initialised (ReDim)
'  - parArray is a dynamic array has been erased (Erase)

  If IsArray(parArray) = False Then isArrayEmpty = True

  On Error Resume Next

  If UBound(parArray) < LBound(parArray) Then
      isArrayEmpty = True
      Exit Function
  Else
      isArrayEmpty = False
  End If

End Function

回答by sancho.s ReinstateMonicaCellio

I am simply pasting below the code by the great Chip Pearson.
Also check out his page on array functions.

我只是在伟大的 Chip Pearson 的代码下面粘贴。
还可以查看他关于数组函数的页面。

I hope this helps.

我希望这有帮助。

Public Function IsArrayEmpty(Arr As Variant) As Boolean
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
' IsArrayEmpty
' This function tests whether the array is empty (unallocated). Returns TRUE or FALSE.
'
' The VBA IsArray function indicates whether a variable is an array, but it does not
' distinguish between allocated and unallocated arrays. It will return TRUE for both
' allocated and unallocated arrays. This function tests whether the array has actually
' been allocated.
'
' This function is really the reverse of IsArrayAllocated.
'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''

    Dim LB As Long
    Dim UB As Long

    err.Clear
    On Error Resume Next
    If IsArray(Arr) = False Then
        ' we weren't passed an array, return True
        IsArrayEmpty = True
    End If

    ' Attempt to get the UBound of the array. If the array is
    ' unallocated, an error will occur.
    UB = UBound(Arr, 1)
    If (err.Number <> 0) Then
        IsArrayEmpty = True
    Else
        ''''''''''''''''''''''''''''''''''''''''''
        ' On rare occassion, under circumstances I
        ' cannot reliably replictate, Err.Number
        ' will be 0 for an unallocated, empty array.
        ' On these occassions, LBound is 0 and
        ' UBound is -1.
        ' To accomodate the weird behavior, test to
        ' see if LB > UB. If so, the array is not
        ' allocated.
        ''''''''''''''''''''''''''''''''''''''''''
        err.Clear
        LB = LBound(Arr)
        If LB > UB Then
            IsArrayEmpty = True
        Else
            IsArrayEmpty = False
        End If
    End If

End Function

回答by Siddharth Rout

Try this

尝试这个

Sub Sample()
    Dim Ar As Variant
    Dim strTest As String

    strg = "Blah"
    Ar = Split(strg, "|")
    Debug.Print "TEST1 : "; IsArrayEmpty(Ar)

    strg = "Blah|Blah"
    Ar = Split(strg, "|")
    Debug.Print "TEST2 : "; IsArrayEmpty(Ar)

End Sub

Function IsArrayEmpty(Ar As Variant) As Boolean
    If InStr(TypeName(Ar), "(") > 0 Then
        If Not IsEmpty(Ar) Then
            If UBound(Ar) > 0 Then
                IsArrayEmpty = False
            Else
                IsArrayEmpty = True
            End If
        End If
    End If
End Function

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does your code assume the array stores strings only? – TPG 7 mins ago

您的代码是否假定数组仅存储字符串？– TPG 7 分钟前

Yes. It did. If you want to test for all conditions then I would recommend using the API. Here is an example

是的。它做了。如果您想测试所有条件，那么我建议使用 API。这是一个例子

Private Declare Sub CopyMemory Lib "kernel32" Alias "RtlMoveMemory" _
(pDst As Any, pSrc As Any, ByVal ByteLen As Long)

Sub Sample()
    Dim Ar() As Long

    Debug.Print ArrayNotEmpty(Ar) '<~~ False

    ReDim Ar(1)

    Debug.Print ArrayNotEmpty(Ar) '<~~ True
End Sub

Public Function ArrayNotEmpty(Ar) As Boolean
    Dim Ret As Long

    CopyMemory Ret, ByVal VarPtr(Ar) + 8, ByVal 4
    CopyMemory Ret, ByVal Ret, ByVal 4
    ArrayNotEmpty = (Ret <> 0)
End Function