[Omaha.pm] FW: Huh?

[Jay Hannah]

-----Original Message-----
From: Thompson, Kenn [mailto:KThompson at heiskell.com] 
Sent: Wednesday, January 17, 2007 10:49 AM
To: Jay Hannah
Subject: RE: Huh?

-->> 
-->> > Just ran across this and it stuck me as weird. Any idea why this
-->> happens?
-->> >  
-->> > Given a regex "^$|^\d{1,7}$" ,  the rule says
-->> > "A 0 length string OR a number 1 to 7 characters in length". 
-->> 
-->> It does? Are you sure about that first dollar sign? Wacky. 

Well, it kind of did. The test script passed it, but the app did not.

-->> 
-->> In Perl the regex you describe would be 
-->> 
-->>     /^(|\d{1,7})$/   (untested)
-->> 
-->> or
-->> 
-->>     /^\d{1,7}?$/     (untested)
-->> 
-->> ^ and $ would only occur at the very start and the very end.
-->> 
-->> > Given a regex "^\d{1,7}|^$" ,  the rule says
-->> > "A number 1 to 7 characters in length OR a 0 length string ".
-->> > 
-->> > For reasons I can't seem to fathom, the first regex evals the
-->> > way I want, the second fails the empty string test. Ever seen 
-->> > this before? Perhaps it's just a weird .NET regex quirk?
-->>  
-->> Uhh... I think my examples would pass in Perl. I can't 
-->> comment on .NET off the top of my head. :)
-->> 

It's weird that it didn't complain about the multiple $. Your examples
work
as written tho (and make more sense to me). I forgot about the parens
usage.
I guess I need to go back to regex school. ;)