I wonder if there's a better way to do this?

I want to build an array of line numbers where a date falls within the
Dates in Cols K and M.

The Date in 'K' is always before 'M' and they're formatted as text "03
Jan 1965" etc.

At the moment I'm using a For Next Loop to look at every line
in the sheet. This seems wasteful as there are several thousand
lines and only 100 or less cases that will match. OR - does this not
matter i.e. every line would need checking anyway?

Here's what I have :-

Variable A holds the target date.
(LastRow is from Ron de Bruin's Last Function)
----
For f = 2 To LastRow
If inTheRange(.Cells(f, "K"), .Cells(f, "M"), A) Then
ReDim Preserve l(UBound(l) + 1)
l(UBound(l)) = f
End If
Next f

Function inTheRange(DateIn, DateOut, ThisDate) As Boolean
If IsDate(DateIn) = True Then
If IsDate(DateOut) = True Then
If CDate(ThisDate) = CDate(DateIn) And CDate(ThisDate) <=
CDate(DateOut) Then inTheRange = True
End If
End If
End Function
----

Thanks for any suggestions.

Cheers - Kirk