walk me through this code for comparing values in a column

[ammartino44]

Hello. Could someone walk me through with a LOT of of detail what this code is doing and what each piece of the code means? Thanks!!

Sub comparevalues()
Dim sws, dws As Worksheet
Dim rng, rng1, cell As Range
Dim lr As Long
Dim n As Integer
Set sws = ThisWorkbook.Sheets("Sheet1")
Set dws = ThisWorkbook.Sheets("Sheet2")
sws.Activate
lr = sws.Cells(Rows.Count, 2).End(xlUp).Row
Set rng = sws.Range("B2:B" & lr)
Set rng1 = sws.Range("P2:P" & lr)
Application.ScreenUpdating = False
sws.Range("B1:C1").Copy dws.Range("A1")
sws.Range("P1:Q1").Copy dws.Range("C1")
For Each cell In rng
    On Error Resume Next
    n = WorksheetFunction.Match(cell, rng1, 0)
    If Err = 0 Then
        If cell.Offset(0, 1) <> Cells(n + 1, "Q") Then
            Cells(n + 1, "R") = "Wrong Amount"
            cell.Resize(1, 2).Copy dws.Range("A" & Rows.Count).End(3)(2)
            Cells(n + 1, "P").Resize(1, 2).Copy dws.Range("C" & Rows.Count).End(3)(2)
        End If
    End If
    Err = 0
Next cell
Columns("R:S").AutoFit
Application.ScreenUpdating = True
End Sub

[mikeTRON]

I think this will help you if you are not familiar with walking through code.
http://www.cpearson.com/excel/DebuggingVBA.aspx

[mikeTRON]

I think some of this code is from Excel 2003, and I am a newb when it comes to VBA but I have commented about every line of code.

Copy and paste this into the VBA editor to have it display the comments in a different color

Sub comparevalues()

'=============================================
'Declare Variables
'=============================================
Dim sws As Worksheet
Dim dws As Worksheet
Dim rng As Range
Dim rng1 As Range
Dim cell As Range
Dim lr As Long
Dim n As Integer

'=============================================
'Define Variables
'=============================================
Set sws = ThisWorkbook.Sheets("Sheet1") 'This sets the variable sws to "Sheet1" in this workbook
Set dws = ThisWorkbook.Sheets("Sheet2") 'This sets the variable sws to "Sheet2" in this workbook
sws.Activate 'this activates sws (or Sheet1)
lr = sws.Cells(Rows.Count, 2).End(xlUp).Row 'This declares lr as the last used cell in column B by starting from the bottom and going up to the first cell used
Set rng = sws.Range("B2:B" & lr) 'this defines rng as B2:B(Last Row number used)
Set rng1 = sws.Range("P2:P" & lr) 'this defines rng1 as P2:P(last rell used just like above)

'==========================================================================================================
' Example to clarify in comments directly below
'==========================================================================================================
'So the easy way to explain the above is lr probably stands for LASTROW and it finds the last row used
'    by going to the very bottom of column B then going up to find the first non empty cell
'        For simplicity lets assume lr=650
'    So once we declared lr, then you then define rng as B2:B650 and rng1 as P2:P650
'All in that is all used to allow for a dynamic range that will adjust as you get more rows used
'==========================================================================================================

Application.ScreenUpdating = False ' 'turns Off Screen updating for SPEED mostly

sws.Range("B1:C1").Copy dws.Range("A1") 'This copies Sheet1 cells B1:C1 to Sheet2 cells A1:B1
sws.Range("P1:Q1").Copy dws.Range("C1") 'This copies Sheet1 cells P1:Q1 to Sheet2 cells C1:D1

'=============================================
'Begin loop
'=============================================
For Each cell In rng 'This says loop through EACH cell in the defined range "rng"
    On Error Resume Next 'If there is an error, simply go to the next cell in the range "rng"
    
    n = WorksheetFunction.Match(cell, rng1, 0) 'This declares variable "n" (which was NOT defined above!) as the matching row # in rng1
    If Err = 0 Then 'If no error then proceed with the following
        If cell.Offset(0, 1) <> Cells(n + 1, "Q") Then 'This verifies that the cell to the right of the active cell is NOT equivalent to the column Q and row below "n" defined above
        'If above statement is true, then do the following
            Cells(n + 1, "R") = "Wrong Amount" 'In column R and row under the "n" type "Wrong Amount"
            cell.Resize(1, 2).Copy dws.Range("A" & Rows.Count).End(3)(2) 'this selects active cell and one row down and 2 columns to the right _
                                                                        'Then copies it and pastes it to Sheet2 A and bottom of the data
            Cells(n + 1, "P").Resize(1, 2).Copy dws.Range("C" & Rows.Count).End(3)(2)
        End If 'Ends the if statment
    End If
    Err = 0
Next cell 'This goes to the next cell in the range "rng

'=============================================
'End Macro procedures
'=============================================
Columns("R:S").AutoFit 'This auto adjusts the width of the columns
Application.ScreenUpdating = True 'Turns Screen Updating back on
End Sub