求助]如何用VBA遍历指定目录下的所有子文件夹和文件-字典模式

你好，请问
Sub Test() '使用双字典，旨在提高速度
Dim MyName, Dic, Did, I, T, F, TT, MyFileName
T = Time
Set Dic = CreateObject("Scripting.Dictionary") '创建一个字典对象
Set Did = CreateObject("Scripting.Dictionary")
Dic.Add ("D:\"), ""
I = 0
Do While I < Dic.Count
Ke = Dic.keys '开始遍历字典
MyName = Dir(Ke(I), vbDirectory) '查找目录
Do While MyName <> ""
If MyName <> "." And MyName <> ".." Then
If (GetAttr(Ke(I) & MyName) And vbDirectory) = vbDirectory Then '如果是次级目录
Dic.Add (Ke(I) & MyName & "\"), "" '就往字典中添加这个次级目录名作为一个条目
End If
End If
MyName = Dir '继续遍历寻找
Loop
I = I + 1
Loop
Did.Add ("文件清单"), "" '以查找D盘下所有EXCEL文件为例
For Each Ke In Dic.keys
MyFileName = Dir(Ke & "*.xls")
Do While MyFileName <> ""
Did.Add (Ke & MyFileName), ""
MyFileName = Dir
Loop
Next
For Each Sh In ThisWorkbook.Worksheets
If Sh.Name = "XLS文件清单" Then
Sheets("XLS文件清单").Cells.Delete
F = True
Exit For
Else
F = False
End If
Next
If Not F Then
Sheets.Add.Name = "XLS文件清单"
End If
Sheets("XLS文件清单").[A1].Resize(Did.Count, 1) = WorksheetFunction.Transpose(Did.keys)
TT = Time - T
MsgBox Minute(TT) & "分" & Second(TT) & "秒"
End Sub
---------------------------这段代码中 F = True/F = False 的“F”代表什么？？？？

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