VB学习笔记_数组赋值测试

动态数组赋值，两种写法都可以正确执行：

'第一种写法：Dim a As Variant
Private Sub cmdCommand1_Click()
    Dim a As Variant
    a = "1,2,3,4,dsd-ad5,6,45,65345"
    Dim b() As String
    b = Split(a, ",")
    Debug.Print b(4)
End Sub

'第二种写法：Dim a 
Private Sub cmdCommand1_Click()
    Dim a
    a = "1,2,3,4,dsd-ad5,6,45,65345"
    Dim b() As String
    b = Split(a, ",")  'b()=Split(a, ",")也可以
    Debug.Print b(4)
End Sub

但以下写法却报错：

Private Sub cmdCommand1_Click()
    Dim a              '即使写成 Dim a as variant 或者 string，也报错
    a = "1,2,3,4,dsd-ad5,6,45,65345"
    Dim b()            '即使写成 Dim b() as variant也报错          
    b = Split(a, ",")  
    Debug.Print b(4)
End Sub

这是什么原因，谁知道请指点一下