类模块数组属性 ByRef Variant Index
设置数组属性（ByRef），其中修改了传递的参数值，为何不能够改变被传址数组的值
如何使类的属性既能传递给数组，又能传递给数组的一个元素？


Class1.cls

VB code

Option ExplicitPrivate B() As BytePublic Property Get mArray() As Byte()               'Optional bIndex As Variant  'If IsMissing(bIndex) Then    Let mArray = B()  'Else    'mArray = b(bIndex)  'End IfEnd PropertyRem                                                  如何既能传递数组，又能传递数组的一个元素Public Property Let mArray(ByRef vData() As Byte)    'Optional bIndex As Variant  'If IsMissing(bIndex) Then    Erase B()    Let B() = vData()  'Else    'b(bIndex) = vData(vIndex)  'End If    On Error GoTo ErrCancel:  If CStr((LBound(vData()))) <> "" Then    vData(LBound(vData())) = 123                     '测试 Byref 是否能够改变被传址数组的值  End If  Stop  Exit PropertyErrCancel:  On Error GoTo 0End PropertyPublic Property Let Test(ByRef mString As String, mStart As Long, Optional mLength As Variant, vData As String)  If IsMissing(mLength) Then    Mid(mString, mStart) = vData  Else    Mid(mString, mStart, mLength) = vData  End IfEnd PropertyPublic Property Get Test(mString As String, mStart As Long, Optional mLength As Variant) As String  If IsMissing(mLength) Then    Test = Mid(mString, mStart)  Else    Test = Mid(mString, mStart, mLength)  End IfEnd Property

Form1.frm

VB code

Option ExplicitPrivate Sub Command1_Click()  Dim Cls1 As Class1  Set Cls1 = New Class1  Dim B() As Byte  ReDim B(30) As Byte    Rem 测试1  Dim S As String  S = "abcdefg"  Cls1.Test(S, 1, 3) = "12"  Debug.Print Cls1.Test(S, 1, 3)      'Byref 起到作用  '__________________________________________  Debug.Print      Rem 测试2  B(LBound(B())) = 234  Let B() = Cls1.mArray()  On Error Resume Next  Debug.Print B(LBound(B()))         'Cause an error  ReDim B(10) As Byte  Let Cls1.mArray() = B()            'Byref 没有起到作用  Debug.Print B(LBound(B()))  StopEnd Sub

[解决办法]
对啊

只有 Property Let 类属性中才会这样

只能用 Sub 或 Function ( ) 才有办法用 ByRef 喔


[解决办法]
Property Let 与 Functiont 和 Sub 不同之处就
1是没有返回值
2是只能用于属性表达式或Let语句的左边

也就是你示例代码中：Let Cls1.mArray() = B() 这一行，对表达式右边的数组B没有作用，也就是B不作为返回值返回你的修改...
作为参数，数组缺省就是ByRef，但属性的参数（你代码中的vData）是由赋值表达式的右边传递的，这就是与 Functiont 和 Sub 的参数不同之处...所以只能说你代码中第二个Property Let似是而非，改变的并非与属性相关的vData....
[解决办法]
你这是写的什么呀。
很简单的：

Public Property Get mArray() As Byte()
mArray = B
End Property

Public Property Let mArray(vData() As Byte)
b=vdata
End Property

'给单个元素赋值
Public Property Let item(index as long, v as byte)
b(index)=v
End Property