byval 对引用类型无效么？？
Public Class Class2
Public a As Integer

End Class


Public Class Form1

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

Dim a As New Class2
a.a = 5
ccc(a)
TextBox1.Text = a.a


End Sub


Public Sub ccc(ByVal b As Class2)


b.a = 3


End Sub


End Class


输出3

[解决办法]
我的理解是这里的b只是形参，所以只存在一个引用a，不管用ByRef还是ByVal都是输出3。