>Thanks, Tamar
>
>That's exactly as I learnt it and understood it (if you read my question then I roughly described it thus). OK I was interested in how George would do that in a do while loop.
>
>Terry
>
>>>... As I learnt it in college it means going backward and foreward in the list, halving the distance as you go (in essence). If that's so, please could you indicate how does ascan() do it, and how you would do it via a do while?
>>>
Terry,

Here's an example. I'm doing this off the top of my head, so it hasn't been debugged. Nevertheless, it should be close enough. If there are questions (or mistakes) please let me know. This function will return either the offset into a single dimension array, or the next greatest value. Naturally, the array is passed by referene

FUNCTION BArraySearch

LPARAMETERS tarray, tsearchfor, tlsoftsearch

LOCAL lnfirst, lnlast, lnmid, llfound, lnresult
lnfirst = 1
lnlast = ALEN(tarray, 1)
llfound = .F.
lnresult = 0
DO WHILE NOT llfound AND lnfirst < lnlast
  lnmid = INT(lnfirst + lnlast)
  llfound = (tsearchfor = tarray[lnmid])
  IF NOT llfound THEN
    IF tsearchfor > tarray[lnmid] THEN
      lnfirst = lnmid + 1
    ELSE
      lnlast = lnmid - 1
    ENDIF
  ENDIF
ENDDO
IF llfound THEN
  lnresult = lnmid
ELSE
  IF llsoftsearch THEN
    lnresult = lnlast
  ENDIF
ENDIF
RETURN lnresult

The beauty of this is that it can be implemented, not only with a array, but an ordered list or cursor.