附件双色球自选号，现在有两个问题不能实现，1.不能出现‘ 0 2.号码不能重复。大家讨论下。

附件以双色球为例现在0不会出现了；待解决号码不能重复。
请问怎样才能让随机数不重复?
  Dim b As New System.Random


        Dim c As Integer

        
        Me.TextBox7.Text = ""

        Dim rand As New Random()
        c = rand.Next(1, 9)
        Me.TextBox7.Text = CStr(c)
        Dim a(7) As Decimal

        Dim i As Integer







        Me.TextBox1.Text = ""
        For i = 1 To 7
            a(i) = b.Next(1, 33)




            Me.TextBox1.Text = Me.TextBox1.Text + CStr(a(i)) + " "
        Next

对的