求大神解释下这个VBA的函数，是做什么的？

求大神解释下这个VBA的函数，是做什么的，并且举个例子，非常感谢！

Public Function Position_Element(Data_Src As String, Data_ToSearch As String) As Integer

Dim Num_Element As Integer
Dim Txt As String
Dim Str_C As String

Data_Src = UCase(Data_Src)
Data_ToSearch = UCase(Data_ToSearch)
Position_Element = 0

If Data_Src = "" Or Data_ToSearch = "" Then
Exit Function
End If

If Data_Src = Data_ToSearch Then
Position_Element = 1
Exit Function
End If

If InStr(1, Data_Src, Data_ToSearch) Then
Num_Element = 1
Txt = ""
For p = 1 To Len(Data_Src)
Str_C = Mid(Data_Src, p, 1)
Select Case Str_C
Case ","
If Txt = Data_ToSearch Then
Position_Element = Num_Element
Exit Function
Else
Num_Element = Num_Element + 1
Txt = ""
End If
Case Else
Txt = Txt & Str_C
End Select
If p = Len(Data_Src) And Txt = Data_ToSearch Then Position_Element = Num_Element
Next p
End If

End Function

这个函数的作用是：
数学,语文,思想政治,英语,化学
请问，“英语”排在上述字符串第几的位置？这个函数就是告诉你 4

如果是excel的VBA，有个现成的函数叫做Split，可以大大简化这个代码，不需要写得那么复杂~

function he(st as range, ed as range) he.value = application.worksheetfunction.sum(st,ed) end function