I rather like punkkid's answer but, in the spirit of TIMTOWTDI, here's another way.

my $index = rindex($string, ' ', 15);
# Chop it at 15 even if we didn't find a space...
$index = 15 if($index < 0);
$string = substr($string, 0, $index);
[download]

Note, however, that this will be foiled on words separated with more than one space... Or tabs.

You could, of course, do away with the synthetic variable ($index) if you don't care about chopping non-space containing strings... But you probably do. That would make it a one-liner. =)

bbfu
Seasons don't fear The Reaper.
Nor do the wind, the sun, and the rain.
We can be like they are.