Sum Column B based on Column A using Excel VBA Macro

Question

OK, I have a simple problem that I need help with in a VBA Macro. I have an excel sheet that looks like this...

Product #     Count
101              1
102          


        

Answer 1

Here is a VBA solution that uses multidimensional arrays. I noticed you said you are a bit new to VBA so I tried to put some meaningful comments in there. One thing that might look strange is when I redimension the arrays. That's because when you have multidimensional arrays you can only ReDim the last dimension in the array when you use the Preserve keyword.

Here is how my data looked:

Product Count
101     1
102     1
101     2
102     2
107     7
101     4
101     4
189     9

And here is the code. It has the same output as my last answer. Test this in a new workbook and put the test data in Sheet1 with headers.

Option Explicit

Sub testFunction()
    Dim rng As Excel.Range
    Dim arrProducts() As String
    Dim i As Long

    Set rng = Sheet1.Range("A2:A9")

    arrProducts = getSumOfCountArray(rng)

    Sheet2.Range("A1:B1").Value = Array("Product", "Sum of Count")

    ' go through array and output to Sheet2
    For i = 0 To UBound(arrProducts, 2)
        Sheet2.Cells(i + 2, "A").Value = arrProducts(0, i)
        Sheet2.Cells(i + 2, "B").Value = arrProducts(1, i)
    Next

End Sub

' Pass in the range of the products
Function getSumOfCountArray(ByRef rngProduct As Excel.Range) As String()
    Dim arrProducts() As String
    Dim i As Long, j As Long
    Dim index As Long

    ReDim arrProducts(1, 0)

    For j = 1 To rngProduct.Rows.Count
        index = getProductIndex(arrProducts, rngProduct.Cells(j, 1).Value)
        If (index = -1) Then
            ' create value in array
            ReDim Preserve arrProducts(1, i)
            arrProducts(0, i) = rngProduct.Cells(j, 1).Value ' product name
            arrProducts(1, i) = rngProduct.Cells(j, 2).Value ' count value
            i = i + 1
        Else
            ' value found, add to id
            arrProducts(1, index) = arrProducts(1, index) + rngProduct.Cells(j, 2).Value
        End If
    Next

    getSumOfCountArray = arrProducts
End Function

Function getProductIndex(ByRef arrProducts() As String, ByRef strSearch As String) As Long
    ' returns the index of the array if found
    Dim i As Long
    For i = 0 To UBound(arrProducts, 2)
        If (arrProducts(0, i) = strSearch) Then
            getProductIndex = i
            Exit Function
        End If
    Next

    ' not found
    getProductIndex = -1
End Function