Formula or VBA to populate blank cells

[OfficeUser]

Hopefully I can explain properly, so here goes.

In column A:C I have data in some cells while others are blank.

[TABLE="width: 207"]
<colgroup><col span="2"><col></colgroup><tbody>[TR]
[TD]Red [/TD]
[TD]Q30[/TD]
[TD="align: right"]1[/TD]
[/TR]
[TR]
[TD]Blue[/TD]
[TD][/TD]
[TD="align: right"]2[/TD]
[/TR]
[TR]
[TD]Green[/TD]
[TD]QX70[/TD]
[TD="align: right"]3[/TD]
[/TR]
[TR]
[TD]Yellow[/TD]
[TD]QX70[/TD]
[TD="align: right"]3[/TD]
[/TR]
[TR]
[TD]White[/TD]
[TD]FX50S[/TD]
[TD="align: right"]4[/TD]
[/TR]
[TR]
[TD]Purple[/TD]
[TD]Q50[/TD]
[TD="align: right"]5[/TD]
[/TR]
[TR]
[TD]Black[/TD]
[TD]FX35[/TD]
[TD="align: right"]6[/TD]
[/TR]
[TR]
[TD]Gray[/TD]
[TD][/TD]
[TD="align: right"]6[/TD]
[/TR]
[TR]
[TD]White[/TD]
[TD][/TD]
[TD="align: right"]6[/TD]
[/TR]
[TR]
[TD]Orange[/TD]
[TD][/TD]
[TD="align: right"]6[/TD]
[/TR]
[TR]
[TD]Teal[/TD]
[TD]QX80[/TD]
[TD="align: right"]7[/TD]
[/TR]
[TR]
[TD]Violet[/TD]
[TD][/TD]
[TD="align: right"]8[/TD]
[/TR]
[TR]
[TD]Tan[/TD]
[TD]Q50[/TD]
[TD="align: right"]9[/TD]
[/TR]
</tbody>[/TABLE]

I am looking for a way to look at the row the blank cell is in, compare the value in C to the one above it, and if the same populate the value in B with the one above it. It would look like this:

[TABLE="width: 207"]
<colgroup><col span="2"><col></colgroup><tbody>[TR]
[TD]Red [/TD]
[TD]Q30[/TD]
[TD="align: right"]1[/TD]
[/TR]
[TR]
[TD]Blue[/TD]
[TD][/TD]
[TD="align: right"]2[/TD]
[/TR]
[TR]
[TD]Green[/TD]
[TD]QX70[/TD]
[TD="align: right"]3[/TD]
[/TR]
[TR]
[TD]Yellow[/TD]
[TD]QX70[/TD]
[TD="align: right"]3[/TD]
[/TR]
[TR]
[TD]White[/TD]
[TD]FX50S[/TD]
[TD="align: right"]4[/TD]
[/TR]
[TR]
[TD]Purple[/TD]
[TD]Q50[/TD]
[TD="align: right"]5[/TD]
[/TR]
[TR]
[TD]Black[/TD]
[TD]FX35[/TD]
[TD="align: right"]6[/TD]
[/TR]
[TR]
[TD]Gray[/TD]
[TD]FX35[/TD]
[TD="align: right"]6[/TD]
[/TR]
[TR]
[TD]White[/TD]
[TD]FX35[/TD]
[TD="align: right"]6[/TD]
[/TR]
[TR]
[TD]Orange[/TD]
[TD]FX35[/TD]
[TD="align: right"]6[/TD]
[/TR]
[TR]
[TD]Teal[/TD]
[TD]QX80[/TD]
[TD="align: right"]7[/TD]
[/TR]
[TR]
[TD]Violet[/TD]
[TD][/TD]
[TD="align: right"]8[/TD]
[/TR]
[TR]
[TD]Tan[/TD]
[TD]Q50[/TD]
[TD="align: right"]9
[/TD]
[/TR]
</tbody>[/TABLE]

If they dont match then it simply stays blank. I would want to do this for rows 1:10000. Any ideas how to do this using a formula or a macro? Thank You!

 

[JoeMo]

Here's a macro you can try. Assumes data starts A1.

Sub OfficeUser()
Dim c As Range
On Error Resume Next
Application.ScreenUpdating = False
For Each c In Range("B:B").SpecialCells(xlCellTypeBlanks)
    If c.Offset(0, 1).Value = c.Offset(-1, 1).Value Then c.Value = c.Offset(-1, 0).Value
Next c
Application.ScreenUpdating = True
End Sub

 

[mumps]

Assuming your data starts in row 2:

Sub CopyCell()
    Application.ScreenUpdating = False
    Dim LastRow As Long
    LastRow = Cells.Find("*", SearchOrder:=xlByRows, SearchDirection:=xlPrevious).Row
    Dim rng As Range
    For Each rng In Range("B2:B" & LastRow)
        If rng = "" Then
            If rng.Offset(0, 1) = rng.Offset(-1, 1) Then
                rng = rng.Offset(-1, 0)
            End If
        End If
    Next rng
    Application.ScreenUpdating = True
End Sub

 

[OfficeUser]

Both work well, I just need to figure out how to speed them up. I am using this instead but still very slow. Thanks to you both, I appreciate it!!

[COLOR=#333333]For Each rng In Range("B2:B10000")[/COLOR]

 

[SpillerBD]

Both work well, I just need to figure out how to speed them up. I am using this instead but still very slow. Thanks to you both, I appreciate it!!

[COLOR=#333333]For Each rng In Range("B2:B10000")[/COLOR]

I would say Mumps since he limits the last row, but not to use the loop at all.
I would say leverage the FindSpecial, and then paste the logic formula into those blank cell.

 

[SpillerBD]

So more like...

Sub Macro26()
'
' Macro26 Macro
'
'
   Application.ScreenUpdating = False
    Dim LastRow As Long
    LastRow = Cells(Rows.Count, 1).End(xlUp).Row
    Dim rng As Range
    
    Range("B2:B" & LastRow). _
        SpecialCells(xlCellTypeBlanks).Formula = "=IF(RC[1]=R[-1]C[1],R[-1]C,"""")"
    Range("B2:B" & LastRow).Copy
    Range("B2:B" & LastRow).PasteSpecial Paste:=xlPasteValues, Operation:=xlNone, SkipBlanks _
        :=False, Transpose:=False
    Application.CutCopyMode = False
    
    Application.ScreenUpdating = True
   
    
End Sub

 

[OfficeUser]

I would say Mumps since he limits the last row, but not to use the loop at all.
I would say leverage the FindSpecial, and then paste the logic formula into those blank cell.

Not sure how to remove the loop...

Edit: You beat me to the post...

 

[OfficeUser]

So more like...

Sub Macro26()
'
' Macro26 Macro
'
'
   Application.ScreenUpdating = False
    Dim LastRow As Long
    LastRow = Cells(Rows.Count, 1).End(xlUp).Row
    Dim rng As Range
    
    Range("B2:B" & LastRow). _
        SpecialCells(xlCellTypeBlanks).Formula = "=IF(RC[1]=R[-1]C[1],R[-1]C,"""")"
    Range("B2:B" & LastRow).Copy
    Range("B2:B" & LastRow).PasteSpecial Paste:=xlPasteValues, Operation:=xlNone, SkipBlanks _
        :=False, Transpose:=False
    Application.CutCopyMode = False
    
    Application.ScreenUpdating = True
   
    
End Sub

Works much faster. Thanks!