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

Assuming the data is in columns A and B, you can do it with a formula:

=SUMIF(A:A,101,B:B)

Or if you put 101 in C1:

=SUMIF(A:A,C1,B:B)

EDIT

However if you still require VBA, here is my (quick and dirty) proposal - I use a dictionary to keep track of the sum for each item.

Sub doIt()

  Dim data As Variant
  Dim i As Long
  Dim countDict As Variant
  Dim category As Variant
  Dim value As Variant

  Set countDict = CreateObject("Scripting.Dictionary")

  data = ActiveSheet.UsedRange 'Assumes data is in columns A/B

  'Populate the dictionary: key = category / Item = count
  For i = LBound(data, 1) To UBound(data, 1)
    category = data(i, 1)
    value = data(i, 2)
    If countDict.exists(category) Then
      countDict(category) = countDict(category) + value 'if we have already seen that category, add to the total
    Else
      countDict(category) = value 'first time we find that category, create it
    End If
  Next i

  'Copy dictionary into an array
  ReDim data(1 To countDict.Count, 1 To 2) As Variant

  Dim d As Variant
  i = 1
  For Each d In countDict
    data(i, 1) = d
    data(i, 2) = countDict(d)
    i = i + 1
  Next d

  'Puts the result back in the sheet in column D/E, including headers
  With ActiveSheet
    .Range("D1").Resize(UBound(data, 1), UBound(data, 2)) = data
  End With

End Sub