Repeat speed and stripping chars

[Geoff Canyon]

At 8:38 AM -0500 1/9/02, Ivers, Doug E wrote:
>Thanks, Geoff!  The speed of "repeat for each char..." is a valuable
>revelation for me!  With this new understanding, what would be the most
>efficient code for a
>"stripChars(theText,theChars)" function?  Normally, I would say "repeat with
>i = number of chars of theText down to 1" so that I can delete chars with
>out messing up the indexing.  Is there a similar way to reverse the "repeat
>for each..."?  If not, should I pull out the chars I want and assemble a new
>return string?

Exactly:

put empty into tResult
repeat for each char C in tMyString
if C is in tMyListOfAcceptableChars then
put C after tResult
end if
end repeat
--tResult is now the string you want.

The repeat with i =... form will be much slower for large strings, and will get slower geometrically. The repeat for each form gets slower linearly. (both assessments are rough estimates)

regards,

Geoff