[FWP] Quick hack for common length

["Clinton A. Pierce" <clintp@geeksalad.org> (by way ofowner-fwp@technofile.org)]

>From fwp-l Mon Jun 25 15:26:34 2001

In #perl today, we were looking at a longest substrings problem,
utilizing a suffix tree solution.  Part of the C code was:

int comlen(char *p, char *q)
{
	i=0;
	while *p && (*p++ == *q++)
		i++;
	return i;
}

A straight translation from C to Perl yeilded something slow.

The quickest solution I could come up with in perl looked like:

sub comlen_or {
	length((($_[0]^$_[1])=~m/^(\0+)/)[0]);
}

Can anyone improve on that for speed?  I was actually happy with
(and then disappointed) with the regular expression.  Is there a
clever way to get rid of it, that list context and $1?
(unpack and bretheren maybe?)

Enjoy.

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