Put entire column (each value in column) in an array?

not sure if anyone else will have this problem or not so I figured I'd post the answer I found. I like the solution of the array posted by @Ripster (and thanks for that, it almost worked) but it won't really work in this case. What I'm working with is a large sheet of data with 1 ID column, and I want to check other sheets to see if there are duplicates in that sheet (using ID column). not delete though, just mark so I can check them out. With potentially upwards of 50K rows looping through each row would take a LONG time.

So, what I figured out I can do is copy the ID column from the other sheet into the main sheet, and use the conditional formatting option to mark duplicates in some colour. (It'll mark the rows in both columns) and then I can filter the column by colour to show me only the colour I used to mark the duplicates. If I programmatically add a column to the sheet I'm checking with the row numbers, I can even include that column in the main sheet so when I filter for colour I can see which rows they were in their sheet.

After doing that I can record and adapt a macro to do this automatically for my less programming inclined co-workers

Thanks much all!

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Edit - Added Code

After selecting the columns to compare, here is the code to mark the duplicates with red text and no fill:

  Selection.FormatConditions.AddUniqueValues
    Selection.FormatConditions(Selection.FormatConditions.Count).SetFirstPriority
    Selection.FormatConditions(1).DupeUnique = xlDuplicate
    With Selection.FormatConditions(1).Font
        .Color = -16383844
        .TintAndShade = 0
    End With
    Selection.FormatConditions(1).StopIfTrue = False

and then, since both columns have the duplicates marked you select the one that you actually want to examine and heres the code to filter:

`Selection.AutoFilter
ActiveSheet.Range("$C$1:$C$12").AutoFilter Field:=1, Criteria1:=RGB(156, 0 _
    , 6), Operator:=xlFilterFontColor`

(in my test i used column c as the one to filter, that can be programmatically with a cells() reference or a range(cells(), cells()) sort of reference

I wish everyone the best of luck in their future endevors! thanks again to @ripster

Here are three different ways to load items into an array. The first method is much faster but simply stores everything in the column. You have to be careful with this though because it creates a multidimensional array which isn't something that can be passed to AutoFilter.

Method 1:

Sub LoadArray()
    Dim strArray As Variant
    Dim TotalRows As Long

    TotalRows = Rows(Rows.Count).End(xlUp).Row
    strArray = Range(Cells(1, 1), Cells(TotalRows, 1)).Value

    MsgBox "Loaded " & UBound(strArray) & " items!"
End Sub

Method 2:

Sub LoadArray2()
    Dim strArray() As String
    Dim TotalRows As Long
    Dim i As Long

    TotalRows = Rows(Rows.Count).End(xlUp).Row
    ReDim strArray(1 To TotalRows)

    For i = 1 To TotalRows
        strArray(i) = Cells(i, 1).Value
    Next

    MsgBox "Loaded " & UBound(strArray) & " items!"
End Sub

if you know the values ahead of time and just want to list them in a variable you can assign a variant using Array()

Sub LoadArray3()
    Dim strArray As Variant

    strArray = Array("Value1", "Value2", "Value3", "Value4")

    MsgBox "Loaded " & UBound(strArray) + 1 & " items!"
End Sub