怎样用VB产生一个不定个数的随机数组?

Private Sub Command1_Click()
Me.Cls
Dim i As Integer '数组元素的个数
Dim a() As Byte '数组每单元 0-255
Dim nMax As Integer
nMax = 500 '定义最大阀值
Dim s As Integer '数组前几个数的和
Randomize
Do While s < nMax 's >= nMax 跳出循环
i = i + 1
ReDim Preserve a(i)
a(i) = Int(Rnd() * 256) '产生 0-255 的随机数
Print a(i)
s = s + a(i)
Loop
Text1.Text = s 'Text1 显示
End Su