VB代码如何正确使用

我需要自动生成助记码，如Z当归(10头）生成ZDG10T,使用了代码Function GetPY(ByVal str As String) As String Dim i As Integer Dim py As String Dim code As Long For i = 1 To Len(str) code = AscW(Mid(str, i, 1)) If code < 0 Then code = code + 65536 Select Case code Case -20319 To -20284: py = py & "A" Case -20283 To -19776: py = py & "B" Case -19775 To -19219: py = py & "C" Case -19218 To -18711: py = py & "D" Case -18710 To -18527: py = py & "E" Case -18526 To -18240: py = py & "F" Case -18239 To -17923: py = py & "G" Case -17922 To -17418: py = py & "H" Case -17417 To -16475: py = py & "J" Case -16474 To -16213: py = py & "K" Case -16212 To -15641: py = py & "L" Case -15640 To -15166: py = py & "M" Case -15165 To -14923: py = py & "N" Case -14922 To -14915: py = py & "O" Case -14914 To -14631: py = py & "P" Case -14630 To -14150: py = py & "Q" Case -14149 To -14091: py = py & "R" Case -14090 To -13319: py = py & "S" Case -13318 To -12839: py = py & "T" Case -12838 To -12557: py = py & "W" Case -12556 To -11848: py = py & "X" Case -11847 To -11056: py = py & "Y" Case -11055 To -10247: py = py & "Z" Case Else: py = py & Mid(str, i, 1) ' 非汉字保留原字符 End Select Next GetPY = UCase(py) End Function 生成的确是原文字，请问这个是怎么回事