请问 vb中 怎样把一个 long类型的值 赋给byte数组第 n，n+1，n+2，n+3位？

Private Sub Command1_Click()
Dim a, d As Long
Dim b(0 To 20), t As Byte
Dim i, j, k As Integer
a = 123456789
j = 0
'对long进行除10取余的方法,余数就是每次的各位数,存进数组,j是位数
While a <> 0
b(j) = a Mod 10
a = Int(a / 10)
j = j + 1
Wend
'由于每次都是把余数存进数组,所以顺序与原数相反,所以这里进行了逆序操作
For i = 0 To j / 2
t = b(i)
b(i) = b(j - i - 1)
b(j - i - 1) = t
Next i
'把数组的值输出
For i = 0 To j
Print b(i);
Next i
End Sub