Re: right$

[Hans Boldt <boldt@xxxxxxxxxx>]

Bob Cozzi wrote:
> %trimR is expensive? I though only %trim was expensive.
> Since you wrote %TRIMx why don't you make them work faster! :)
> Also, another argument for an INLINE keyword as the overhead of using a
> procedure call far outweighs using %TRIMR in that procedure.

Well, the statement in question is "Eval InString=%Trimr(InString)".

First, is %TRIMR expensive?  %TRIMR is implemented by a loop that
searches backwards through the string character by character until a
non-blank is found.  Well, that's not too bad, unless you have a lot
of trailing blanks.

Second, is string assignment expensive?  Well, in this case, you're
copying character by character from the expression to the target for
the length of the source string.

But if you're trimming the right-most blanks from a varying length
character variable, there's a faster way to do it:

eval %len(string) = %checkr(' ':string);

In this case, you're searching for the right-most non-blank, and
assigning the position of that character to the length of the
character varying string.  If the entire string is blank, then
%CHECKR returns 0, and the length of the string is set to 0.

Sure, %CHECKR involves it's own loop through the string, but in this
case, there's no assignment of possibly lots of characters to the
assignment target.  A quick test showed improvements from around 10%
to 35%, with greater improvement as the number of trailing blanks
increased.  This suggests that %TRIMR may well be the bottleneck.

(OK, the performance improvement isn't that great, and may not
necessarily be worth it overall.  I was just expecting bigger gains
than that.  Like I said, yesterday afternoon I was in a nitpicky mood!)

Cheers!  Hans