vb 去掉最后一个 "\"以及\ 后的内容

st = "c:\aa\bb\cc\dd\ee\jj.exe"
s = Left(st, InStrRev(st, "\"))

函数
Public Function ParsePath(sPathIn As String) As String
ParsePath = sPathIn
For I = Len(sPathIn) To 1 Step -1
If InStr("\", Mid$(sPathIn, I, 1)) Then
ParsePath = Left$(sPathIn, I - 1)
Exit For
End If
Next
End Function

使用方法：
Private Sub Form_Load()
MsgBox ParsePath("12345\121212")
End Sub