Loop through all Sheets in Active Workbook

Retrieve all Worksheets Names in Active Workbook

Option Explicit

Sub LoopAllSheets()

Dim sht As Excel.Worksheet
' declare an array of type String without committing to maximum number of members
Dim sht_Name() As String
Dim i As Integer

' get the number of worksheets in Active  Workbook , and put it as the maximum number of members in the array
ReDim sht_Name(1 To ActiveWorkbook.Worksheets.count)

i = 1

' loop through all worksheets in Active Workbook
For Each sht In ActiveWorkbook.Worksheets
    sht_Name(i) = sht.Name ' get the name of each worksheet and save it in the array
    i = i + 1
Next sht

End Sub

Loop Through all Sheets in all Files in a Folder

Sub Theloopofloops()

 Dim wbk As Workbook
 Dim Filename As String
 Dim path As String
 Dim rCell As Range
 Dim rRng As Range
 Dim wsO As Worksheet
 Dim sheet As Worksheet


 path = "pathtofile(s)" & "\"
 Filename = Dir(path & "*.xl??")
 Set wsO = ThisWorkbook.Sheets("Sheet1") 'included in case you need to differentiate_
              between workbooks i.e currently opened workbook vs workbook containing code

 Do While Len(Filename) > 0
     DoEvents
     Set wbk = Workbooks.Open(path & Filename, True, True)
         For Each sheet In ActiveWorkbook.Worksheets  'this needs to be adjusted for specifiying sheets. Repeat loop for each sheet so thats on a per sheet basis
                Set rRng = sheet.Range("a1:a1000") 'OBV needs to be changed
                For Each rCell In rRng.Cells
                If rCell <> "" And rCell.Value <> vbNullString And rCell.Value <> 0 Then

                   'code that does stuff

                End If
                Next rCell
         Next sheet
     wbk.Close False
     Filename = Dir
 Loop
 End Sub