Comparing cells pairs in a column for duplicates Excel VBA - excel

Question

Hello,
Appreciate your help in advance
I have used this code below to find matching values in a column.
I am looking for help to do the following:
The code below compares all cells in the column at once for matching values starting at cell B3 and going down, then highlights all matching cells. The code works fine.
But Instead, I need to check for duplicates in pairs comparing two cells at a time instead of the whole column, and also in reverse column order starting from the bottom cell in the column and going to top.
Example of match process would be:
Compare Cell B10 = B9 (highlight both if they match, If not, Move to next pair to check, B9 = B8, B8 = B7, and so on )
Dim rg As Range
Set rg = Range("B3", Range("B3").End(xlDown))
Dim uv As UniqueValues
Set uv = rg.FormatConditions.AddUniqueValues
uv.DupeUnique = xlDuplicate
uv.Interior.Color = vbRed
Thanks

Answer 1

First you need a loop, to give you more control over what Excel is doing. Loop over your wanted range like this:
For Each cell In rg
Next cell
But to go backwards, it's harder. You'll have to get the highest and lowest row numbers in your range, and step-1 through them.
for a = rg_highestrow to rg_lowestRow step -1
next
The problem is, this doesn't know what column you're using. The .range object is going to make things complicated. So, write a method that accepts a param of which col you want to do, and what starting and ending row. Like this:
sub find_duplicates(byval colnumber as integer, byval startrow as integer, byval endrow as integer)
end sub
Then you can loop backwards, using step -1:
for a = endrow to startrow step -1
next
You'll need the logic to spot duplicates between the current cell, and the other cell. To do this, refer to the "previous cell". This means, you want to start your loop on the SECOND row, not the first. Like this:
for a = (endrow-1) to startrow step -1
next
This won't work if there's only one row in your range. So test if your range only has one row. If it only has one, a comparison is impossible, so quit. Putting it all together so far:
sub find_duplicates(byval colnumber as integer, byval startrow as integer, byval endrow as integer)
if endrow-startrow<1 then exit sub 'Needs at least 2 rows to function. Exit.
for row_a = (endrow-1) to startrow step -1 'Loop backwards using step-1, but stop short of the very last item.
'Do the comparison of row_a and row_a+1
if Cells(row_a,colnumber).Value = Cells(row_a+1,colnumber).Value then
'They match. Do whatever you need to do
end if
next
end sub
You can call it like this:
find_duplicates(2,10,20)
This will search the indicated column from row 20 to row 10, comparing pairs of rows' cells for duplicate values.

Answer 2

This code below has worked perfectly.
the -1 in the offset formula has helped me compare current cell to previous one (as in reverse order)
Dim rngMyCell As Range
Dim wsMySheet As Worksheet
Application.ScreenUpdating = False
Set wsMySheet = ActiveSheet
For Each rngMyCell In wsMySheet.Range("F3:F" & wsMySheet.Range("F" & Rows.Count).End(xlUp).Row)
If Val(rngMyCell.Offset(-1, 0)) = Val(rngMyCell) Then
wsMySheet.Range("F" & rngMyCell.Row & ":F" & rngMyCell.Row).Interior.Color = RGB(255, 255, 0)
Else
wsMySheet.Range("F" & rngMyCell.Row & ":F" & rngMyCell.Row).Interior.Color = xlNone
End If
Next rngMyCell
Set wsMySheet = Nothing
Application.ScreenUpdating = True