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' Function to create a list of all worksheet names in the active workbook
Function SheetList() As Variant
    ' Makes the function recalculate every time there is a change in the worksheet
    Application.Volatile

    ' Declare variables
    Dim sheet As Worksheet               ' Variable to hold each worksheet during loop
    Dim strSheetList() As String         ' Dynamic array to store worksheet names
    Dim lngNumSheets As Long             ' Counter for number of worksheets

    ' Initialize lngNumSheets based on Option Base setting
    If LBound(Array()) = 1 Then lngNumSheets = 1 ' Initialize to 1 if Option Base 1 is set

    ' Loop through each worksheet in the active workbook
    For Each sheet In ActiveWorkbook.Worksheets
        ' Resize the array to hold an additional worksheet name
        ReDim Preserve strSheetList(lngNumSheets)

        ' Assign the worksheet name to the current position in the array
        strSheetList(lngNumSheets) = sheet.Name

        ' Increment the worksheet counter
        lngNumSheets = lngNumSheets + 1
    Next sheet

    ' Assign the array of worksheet names to the function's return value.
    ' Returns a dynamic array along columns, i.e., 1 row x nn columns.
    ' Use the Transpose() function in Excel to convert it into a list down a single column, i.e., nn rows x 1 column.
    SheetList = strSheetList()
End Function

Function SheetList() As Variant
    Application.Volatile ' This makes the function recalculate whenever any cell in the workbook changes
    
    Dim sheet As Worksheet, strSheetList() As String, lngNumSheets As Long ' This declares the variables for the sheet object, the array of sheet names, and the number of sheets
    If LBound(Array()) = 1 Then lngNumSheets = 1 ' This checks if the lower bound of the array is 1, which means the Option Base setting is 1, and sets the initial value of lngNumSheets accordingly