Loop through first cells of selected merged ranges only - excel

Question

I am trying to give the user the option to do simple arithmetic operations on selected cells.
The thing is that most cells are merged ranges.
I got the following already but the problem with it is that it loops through all cells while I only want it to only affect those cells that are not merged or only to the first cells of merged ranges.
Sub test()
Application.ScreenUpdating = False
Dim cel As Range
Dim selectedRange As Range
myValue = InputBox("Enter")
Set selectedRange = Application.Selection
For Each cel In selectedRange.Cells
On Error Resume Next
cel.Value = Evaluate(cel.Value & myValue)
Next cel
End Sub

Answer 1

Although VBasic2008's answer works, it's not totally correct. The problem is that each cell in merged range always returns True for MergedCells property. This means that excessive processing is done in a loop (i.e. incrementing a value) for cells other than top-left cell. To fix this situation, you should test each cell for the need to process. You can do this in several ways:
You can compare the address of a cell with the top-left cell address (Option 1 in code).
You can test the length of cell's value. If it's zero, then it's not top-left cell, so you skip it (Option 2 in code).
Code:
Sub IncrValues()
Dim rng As Range, myValue%
myValue = InputBox("Enter")
For Each cell In Selection
If cell.MergeCells Then
'// Option 1:
If cell.Address = cell.MergeArea(1).Address Then
cell.Value = cell.Value + myValue
End If
'// Option 2:
'If Len(cell) > 0 Then
' cell.Value = cell.Value + myValue
'End If
Else
cell.Value = cell.Value + myValue
End If
Next
End Sub

Answer 2

The MergeCells Property
Using the MergeCells property in an If statement, you check if a cell is not merged, then execute the following statement(s), otherwise the statement(s) after Else.
In the following example, the range I3:M12 is selected and 5 is entered as myValue. The first table is the state of the second table before.
The Code
Sub test()
Dim cel As Range
Dim selectedRange As Range
Dim myValue As Double
Application.ScreenUpdating = False
myValue = InputBox("Enter")
Set selectedRange = Application.Selection
For Each cel In selectedRange.Cells
If Not cel.MergeCells Then
' If not merged cell.
cel.Value = Evaluate(cel.Value & myValue)
Else
' if merged cell.
cel.Value = Evaluate(cel.Value + myValue)
End If
Next cel
Application.ScreenUpdating = True
End Sub
Count
We can expand the previous tables by adding a COUNT column,
where it is more obvious how the merged cells are being 'ignored' in Excel i.e. all cells except the first cell of a merged area will not be counted (or summed up, or ...).
The following shows the difference between counting the cells in VBA and in Excel.
Sub MergeTest()
With Range("J3:J12")
Debug.Print .Cells.Count
Debug.Print WorksheetFunction.Count(.Cells)
End With
With Range("J3:N12")
Debug.Print .Cells.Count
Debug.Print WorksheetFunction.Count(.Cells)
End With
End Sub
The results in the Immediate window are
10,
9,
50,
46,
which shows how VBA will count every cell, but Excel will exclude all cells of a merged area except the first.
In VBA Help search for the MergeArea property for some further info.