For every blank cell in column, run an auto fill macro - excel

Question

To this:
I would like the set of code to be able to pick up every blank in column C and perform a macro in it. It would have been easy if my sheet has a fixed range, however, my list is constantly increasing in rows... Hence, I would need the macro to be able to run macro on blank cells and skip on those filled cells. The macro should also end upon the last filled cell in the column.
Sub Testing()
Dim Rl As Long ' last row
Dim Tmp As Variant
Dim R As Long ' row counter
With ThisWorkbook.ActiveSheet ' modify to suit
Rl = .Cells(.Rows.Count, "C").End(xlUp).Row
' work on column C
For R = 1 To Rl ' start the loop in row 1
Tmp = .Cells(R, "C").Value
If Len(Tmp) Then
Cells(R, "C").Select
Call AutoFill
End If
Next R
End With
Sub AutoFill()
Application.EnableEvents = False
Dim rng As Range
Set rng = Range(Selection, Selection.End(xlDown))
Set rng = rng.Resize(rng.Rows.Count - 1, rng.Columns.Count)
rng.FillDown
End Sub

Answer 1

Your problem is here: If Len(Tmp) Then and that's just checking if Tmp has any length. So this actually ignores your empty cells by skipping them. Instead you are selecting cells with values in them.
Do not loop all cells in a range. Instead just look at those empty cells of interest. For example:
Sub Testing()
Dim LR As Long, LC as Long
Dim rng As Range
Dim ws As Worksheet
Set ws = ThisWorkbook.Worksheets("Sheet1")
With ws
LR = .Cells(.Rows.Count, "A").End(xlUp).Row
LC = .Cells(LR, .Columns.Count).End(xlToLeft).Column
Set rng = .Range(.Cells(1, 1), .Cells(LR, LC))
If WorksheetFunction.CountBlank(rng) > 0 Then
For Each area In rng.SpecialCells(xlCellTypeBlanks).Areas
area.Offset(-1).Resize(area.Rows.Count + 1).FillDown
Next
End If
End With
End Sub
As you can see I left out .Select and ActiveSheet as that's poor coding and usually not needed at all.