Is it possible to fill an array with row numbers which match a certain criteria without looping?

Question

I would like to fill an array in VBA with the row numbers of only rows which meet a certain criteria. I would like the fastest method possible (for example, something like <

Answer 1

There is an assumption in the question title: that a looping solution is slow and a non-looping solution is faster. So, I conducted some comparisons to check that.

Test Case

I created some sample data consisting of 50,000 samples, and 50% matching values. For the fastest methods I created two more sample sets, again with 50,000 rows and one with 10% matching rows, another with 90% matching row.

I ran each of the posted methods over this data in a loop, repeating the logic 10 times (so times are for processing a total of 500,000 rows).

                  50%        10%        90%  
ExactaBox        1300       1240       1350  ms
Scott Holtzman 415000         
John Bustos     12500       
Chris neilsen     310        310        310
Brettdj           970        970        970
OP               1530       1320       1700

So the moral is clear: just because it includes a loop, doesn't make it slow. What is slow is access the worksheet, so you should make every effort to minimise that.

Update Added test of Brettdj's comment: single line of code

For completeness sake, here's my solution

Sub GetRows()
    Dim valMatch As String
    Dim rData As Range
    Dim a() As Long, z As Variant
    Dim x As Long, i As Long
    Dim sCompare As String

    Set rData = Range("A1:A50000")
    z = rData
    ReDim a(1 To UBound(z, 1))
    x = 1
    sCompare = "aa"
    For i = 1 To UBound(z)
        If z(i, 1) = sCompare Then a(x) = i: x = x + 1
    Next
    ReDim Preserve a(1 To x - 1)    
End Sub