VB程序编写二进制转变成八进制

Private Sub Command1_Click()
Dim a As String, b As Long, c As String
a = Trim(InputBox("输入二进制值："))
If Len(a) = 0 Then MsgBox "输入数据错误": Exit Sub
For i = 1 To Len(a)
If Mid(a, i, 1) <> "0" And Mid(a, i, 1) <> "1" Then MsgBox "输入数据错误": Exit Sub
Next i
If (Len(a) Mod 3) > 0 Then a = String((3 - Len(a) Mod 3), "0") + a
For i = Len(a) To 1 Step -3
b = CLng(Mid(a, i, 1)) + 2 * CLng(Mid(a, i - 1, 1)) + 4 * CLng(Mid(a, i - 2, 1))
c = CStr(b) + c
Next i
MsgBox "二进制数" & a & "转换为八进制数为：" & c
End Sub

Public Function BIN_to_OCT(ByVal Bin As String) As String
Dim i As Long
Dim H As String
If Len(Bin) Mod 3 <> 0 Then
Bin = String(3 - Len(Bin) Mod 3, "0") & Bin
End If

For i = 1 To Len(Bin) Step 3
Select Case Mid(Bin, i, 3)