How to sum columns without using Loop in VBA - excel

Question

I am trying to reformat a report so it can feed into my system like below:
wbOutput.Sheets(1).Range("B" & O_lrow + 1 & ":B" & O_lrow + lRow).Value = wbSource.Sheets(1).Range("F1:F" & lRow).Value
One issue I encounter is column F needs to be the sum of two source column and below doesn't work:
wbOutput.Sheets(1).Range("F" & O_lrow + 1 & ":F" & O_lrow + lRow).Value = wbSource.Sheets(1).Range("N1:N" & lRow).Value + wbSource.Sheets(1).Range("O1:O" & lRow).Value
I am trying to avoid using loop as there are many rows and I don't want the marco slow down too much.
Is there any simple way to achieve this without using a loop?

Answer 1

You can try this:
wbOutput.Sheets(1).Range("F" & O_lrow + 1 & ":F" & O_lrow + lRow).Value = _
wbSource.Sheets(1).Evaluate("N1:N" & lRow & " + O1:O" & lRow)

Answer 2

This is a way, using the Application.Sum function:
Option Explicit
Sub SumTest()
Dim SumA As Range
Dim SumB As Range
With wbSource.Sheets(1)
Set SumA = .Range("N1:N" & lRow)
Set SumB = .Range("O1:O" & lRow)
End With
wbOutput.Sheets(1).Range("F" & O_lrow + 1 & ":F" & O_lrow + lRow) = Application.Sum(SumA, SumB)
End Sub

Answer 3

You already have two good answers, just want to add my 2 cents here...
If you have lots of data, you should consider using arrays, and one way of doing what you are trying to achieve can be the below, please see comments for further details:
Dim wsOutput As Worksheet: Set wsOutput = wbOutput.Sheets(1) 'allocate the output worksheet to a variable
Dim wsSource As Worksheet: Set wsSource = wbSource.Sheets(1) 'allocate the source worksheet to a variable
Dim arrSource As Variant
Dim arrOutput() As Variant 'Could change this to match your expected data type output
Dim R As Long, C As Long
arrSource = wsSource.Range("N1:O" & lRow) 'Get the source data into an array
ReDim arrOutput(1 To UBound(arrSource), 1 To 1) 'set the size of the output
For R = 1 To UBound(arrSource)
For C = 1 To UBound(arrSource, 2)
arrOutput(R, 1) = arrSource(R, 1) + arrSource(R, 2) 'make your calculations here
Next C
Next R
wsOutput.Range("F" & O_lrow + 1 & ":F" & O_lrow + lRow) = arrOutput 'spit it back to the sheet once is done