如何在VBA 2003中使用InStr函數？

Question

下面的代碼在調用InStr函數返回的錯誤5：

Option Explicit 

Sub Test() 
    Dim wb As Workbook 
    Dim wbs As Workbooks 
    Dim str As String 
    Dim LPosition As Integer 

    Set wbs = Application.Workbooks 
    For Each wb In wbs 
     str = wb.Name 
     LPosition = InStr(0, str, "_", vbTextCompare) 
     MsgBox LPosition 
    Next wb 
End Sub 

可能有人請解釋一下爲什麼？

Answer 1

InStr函數的起始索引爲1基於=> 0爲無效值。

見例外的http://msdn.microsoft.com/en-us/library/8460tsh1%28v=vs.80%29.aspx