Session Start: Tue Mar 27 10:26:38 2001
*** Now talking in #topniche
*** Topic is 'Week 6 Perl/CGI Class Tech Chat - This week, Intro to CGI.pm'
*** Set by FurBall on Tue Mar 20 12:37:15
-HelpBot- Welcome to Topniche IRC Webmaster Chat. Webmasters only please!
-HelpBot- Our url: http://www.weboverdrive.com/
*** TDavid is now known as TD-lunch
*** FurBall has joined #topniche
*** HelpBot sets mode: +o FurBall
*** FurBall changes topic to ' :Week 7 Perl/CGI Class Tech Chat - This week, regular expressions'
<FurBall> Hey TD
*** TD-lunch is now known as TDavid
<TDavid> hello :)
<FurBall> Hey there...
<TDavid> hmmm we'll give them a few :)
<FurBall> NP.. :)
*** Itchy has joined #topniche
<FurBall> Hey there itchy!
<Itchy> Hello :o)
<Itchy> school today?
<FurBall> Hey TD... Do me a favor please if you would... Could you try posting to the message board.
<FurBall> Yup!
<Itchy> here?
<FurBall> Or you too itchy.
<FurBall> Yup!
<Itchy> whats up?
<Itchy> which board I mean?
<FurBall> Could you try posting a message at the perl message board? 
<FurBall> www.webmastermatrix.com/tech/perl/msgboard/
<FurBall> Specifically week 7.
<Itchy> it's there :o)
<TDavid> on the phone, furball
<FurBall> You had no problems at all?
<FurBall> Ok.. Then it's me.  Good. :)
<FurBall> NP TD...
<Itchy> nope 
<TDavid> with a potential guest for this friday :))
<FurBall> Ahh.. GOOD! :)
<Itchy> what time school today ?
<FurBall> About 5 minutes.
<Itchy> :o)
*** FurBall has quit IRC (QUIT: User exited)
*** FurBall has joined #topniche
<FurBall> Growl....
*** HelpBot sets mode: +o FurBall
*** FurBall has quit IRC (QUIT: User exited)
*** FurBall has joined #topniche
<FurBall> Ok...
<FurBall> Umm.. Are we ready? ;)
*** HelpBot sets mode: +o FurBall
*** FurBall sets mode: +v Itchy
<Itchy> where is everyone ?
*** FurBall sets mode: +v TDavid
<FurBall> They're not here... ;)
<Itchy> eheh and I'm 2 weeks behind now 
<FurBall> Ahh.. This is a good time for catchup then... :)
<FurBall> Do you have any questions?
<Itchy> lots hehe not sure yet 
<FurBall> Before I get into regular expressions that is.
<Itchy> regular what ?? hehe
<FurBall> We can turn this into a one on one for you...
<FurBall> IE if you want to cover previous weeks, that's fine...
<Itchy> just like lat time i learn lots yup
<FurBall> Ok... :)  Shoot with your first question then... :)
<Itchy> ok I never got the url one to work right but looking at whta beth put on the board i see i don't need to make the arrys a link first 
<Itchy> there is a code for making what ever that arry selection a link
<FurBall> Ok...
<FurBall> What was the problem you were having?
<Itchy> I made all the urls a link inside the array
<FurBall> I see that...
<FurBall> Ahh.. I see what you did.
<FurBall> You should have had two arrays.
<FurBall> One for the actual links themselves and then another one for the descriptions.
<Itchy> ok didn't do a description one then
<FurBall> Yup...
<Itchy> print "<a href='$url'>$url</a><br>"; this is what i missed too was doing this code
<Itchy> then this way i skip making the $url a link in side the Array right 
<Itchy> ?
<FurBall> Yup
<FurBall> But you would have to assign a value to $url before you printed it.
<Itchy> so then we have to make so that what ever link it picks it will pick the right description too?
<FurBall> Yup...
<FurBall> That's easy... ;)
<Itchy> ok thats the ? from me then how ?
<FurBall> Just make sure that the descriptions match to the URL.. 
<FurBall> IE if $url[3] = "http://www.yahoo.com" then make sure that $description[3] = "Yahoo"
<FurBall> Then later, assuming $index = 3, if you do this:
<FurBall> Print "<a href='$url[$index]'>$description[$index]</a><br>";
<FurBall> It will print out the url for yahoo and then the description for yahoo.
<Itchy> so then the link would be the description then or all of it ?
<FurBall> Just the description.
<Itchy> ok
<FurBall> Does that answer your question?
<Itchy> yup I see now how to get it and will built a new page after today 
<FurBall> Ok!
<Itchy> now forms :o)
<FurBall> Next question. :)
<FurBall> Shoot. :)
<Itchy> I'm just reading the assignment now :o)
<FurBall> OK... :)
<Itchy> anything thats a little trivcky that i might ned to look out for?
<FurBall> Nope... 
<Itchy> nice spelling today :o)
<FurBall> :)
<FurBall> Are you familiar with forms?
<Itchy> no problem to make forms work all stright forward stuff then?
<FurBall> Yup...
<Itchy> A bit been looking at html forms for submitting to tgps lots 
<FurBall> And since you've already kinda started to get into cgi.pm... 
<Itchy> a bit yup :o)
<FurBall> The format that I use is different than what you use...
<FurBall> I personally like the object method better BUT... Both work!
<Itchy> which is shorter to write ?
<FurBall> Probably the function method.
<Itchy> thats the one for me then hehe
<Itchy> but why do  you like  the object one? what makes you like it better ?
<FurBall> The downside of the function method (and if you're not using something like mod_perl then it's OK) is that it uses a little bit more memory.
<Itchy> AAAA that would make a differnece on a bit script running then right?
<Itchy> bit = big 
<FurBall> Yes!
<FurBall> The other difference is that I'm more "object oriented" in my thinking...
<FurBall> Next question?
<Itchy> =~ /([\w-.]+\@[\w-.]+)/) whats that stuf hehe
<FurBall> OK...
<FurBall> This is a regular expression. :)
<Itchy> looks like fun
<FurBall> :)
<FurBall> ALL a regular expression is is a way to "search" through a string.
<FurBall> It's also VERY handy for testing strings to see if they match a certain value.
<Itchy> just checking what ever some one puts in to a form text area to make sure it's in the right format
<FurBall> IE if you want to make sure that a URL starts out with http://www. A regular expression is the way to go.
<FurBall> That too!
<FurBall> The simplest regular expression is this: .*
<FurBall> Now, what does that mean? :)  
<FurBall> The . Matches any SINGLE character and the * means that we want to match 0 or more single characters.
<FurBall> TO test a string, you have to use the =~ operator.  IE $url =~ /http:\/\/www/
<FurBall> (The \/ escapes the / so that we match a literal / rather than telling it to end the search)
<FurBall> All of the stuff between the two /'s is your regular expression and is what you're searching for.
<Itchy> so =~ tests to make sure there is a http://www there
<FurBall> Yup...
<Itchy> and the \is stoping the script from ending and making it go forward looking for more stuf
<FurBall> Nope.. The \ is used to "escape" the next character.
<Itchy> so it doesn't read the next charater then
<Itchy> kinda like it's not there
<FurBall> There are some "special" characters that if you wanted to match them (such as the .) you have to use the \ to tell perl to match it as a period.
<Itchy> ok 
<FurBall> The next important concept to understand is ranges.
<FurBall> For example, if you wanted to match any urls that started with http://www.f through http://www.j you would use a range.
<FurBall> Like this: /http:\/\/www\.[f-j]/
<FurBall> The [f-j] is a range.
<FurBall> With me so far?
<Itchy> yup
<Itchy> well i think so :o)
<FurBall> Ok.. Now with ranges, you can do neat things. :) 
<Itchy> like.....hehe
<FurBall> For example, let's say we wanted to match f through j, p, and u through z.  
<FurBall> Here's that range: [f-jpu-z]
<FurBall> The f-j matches anything startign with f through j, the p matches anything starting with p, and the u-z matchs anythign starting u through z.
<Itchy> so  you could use that on a link list that rotates then making it look for the right letter every ay
<FurBall> Right!
<Itchy> cool
<FurBall> Now, let's go back to the regular expression you posted and see how much we understand now.
<FurBall> =~ /([\w-.]+\@[\w-.]+)/) 
<FurBall> Ok.. We know what the =~ / does.
<FurBall> We also know what the [] do.  
<FurBall> What does the \@ do?
<TDavid> yikes, i'm back!
<Itchy> looks in a array  for the info ?
<FurBall> Nope...
<FurBall> What does a \ do again?
<Itchy> its being skipped
<FurBall> Escaped...
<FurBall> Not skipped... ;)
<Itchy> looking for the @ sign i nthe e-mail addy 
<FurBall> Right!
<FurBall> Ok.. So all we have left is the () and the \w and the +.
<Itchy>  the inside of () is what is being looked at 
<FurBall> The plus is a special form the the *.  It says rather than matching ZERO or more occcurences, it says we want to match ONE or more.
<FurBall> (nope... We'll get the the () in a sec. :))
<Itchy> ok
<TDavid> it's what they call greedy hehe :)
<FurBall> Yup.. :)
<FurBall> The () are used to group expressions...
<FurBall> For example, say you wanted to match one or more occurences of the string abcd in a string.
<FurBall> The regular expression for that would be /(abcd)+/
<FurBall> IE it applies the + to the expression abcd.  If you wrote it as /abcd+/, then it would match a string of abc followed by one or more d's.
<FurBall> Make sense so far?
<Itchy> so abcd and abcdd are the same
<TDavid> or abcddddddd
<TDavid> yuppers
<FurBall> Using the second expression.. Yes...
<Itchy> ok making some sence then hehe
<FurBall> But NOT using the first expression... IE /(abcd)+/
<FurBall> Well.. Actually, that's not true. :0
<FurBall> Both regular expressions would match abcd and abcdd
<TDavid> yup it would match in the first one
<TDavid> any combination of abcd would match
<TDavid> as long as they were in that order
<FurBall> Right... :)
<Itchy> so dabc is different
<FurBall> SO... ALL we have left is the \w.
<FurBall> BINGO!
<Itchy> ok next hehe
<TDavid> aabbcccddddd matches
<FurBall> Now for a curve... 
<FurBall> Ready? :)
<Itchy> :O)
<FurBall> \w and it's friends are what we call character classes.
<Itchy> freinds ?
<FurBall> Basically, they are shortcuts for HUGE ranges..
<FurBall> For example, \d is the same as the range [0-9].  IE it matches a single digit.
<FurBall> In this case, \w matches an upper or lowercase letter, a digit, or the underscore symbol.
<TDavid> written long like this [(a-zA-z|0-9|_)]
<FurBall> There's about 6 or 8 \ combos for character classes...
<FurBall> Actually, no.. ;)
<FurBall> It would be this: [a-zA-Z0-9_]
<TDavid> that's right no pipes necessary
<TDavid> unless no brackets
<FurBall> And no parens either.. :)
<FurBall> Right!
<TDavid> hehe :)
<TDavid> you know what I meant :)
<FurBall> Does the \w make sense Itchy?  (yes TD, I did. LOL)
<TDavid> sorry bout that itchy
<Itchy> is ok and yup reading a bit on that too in week
<TDavid> the point is if you didn't use shortcuts then the code would be VERY confusing to look at
<TDavid> er, the regexp that is
<FurBall> Right!
<FurBall> OK... So let's look at that regular expression again: =~ /([\w-.]+\@[\w-.]+)/) 
<FurBall> What does the [\w-.]+ do?
<Itchy> there has to be a upper oe lower case letter od number aor digit there
<TDavid> it must START with that
<FurBall> Yes... And whatelse?
<Itchy> then looks for a @ sign with the +
<TDavid> think of how an email address is structured ... it will help you
<FurBall> No... 
<TDavid> abc@123.com
<FurBall> The + says we want to match one or more of the PREVIOUS expressions... 
<FurBall> IE in this case the [\w-.] expression.
<TDavid> its_my_emailaddy@anydomain.com
<FurBall> What does the \@ do?
<Itchy> makes sure that @ is there 
<FurBall> yup
<Itchy> looks to make sure it's in the string
<FurBall> Ok.. Final question.  Do we need the () in the expression?
<Itchy> yes
<FurBall> Why?
<Itchy> we just talked about that
<FurBall> What is it doing?
<Itchy> or else it looks for something else
<Itchy> grouping the expresa.
<TDavid> yup, it groups the expression
<FurBall> But it's grouping the entire expression...
<FurBall> (As an aside, if we were doing a search and replace with this, then yes, there would be a good reason for the () :) )
<FurBall> So if it's grouping the entire expression...do we really need the () after all? 
<Itchy> I'm not sure but i want to say no we don't need them there
<FurBall> You are right... But do you know why? 
<TDavid> furball can ya give me a call when we're done here mon?
<FurBall> (sure can!)
<FurBall> Let me put it this way... What's the difference between =~ /([\w-.]+\@[\w-.]+)/) 
<FurBall>  And =~ /[\w-.]+\@[\w-.]+/ ?
<FurBall> If any?
<FurBall> P.S. The final ) is just a typo...
<Itchy> aaaaaaaaa'
<FurBall> Yes?
<Itchy> ..../>>>>>>/ works like (........)
<FurBall> Bingo! :)
<Itchy> lost the ? because the first letter was a /
<FurBall> Remember, the regular expression is what is between the two /'s. 
<Itchy> must be a mirc thing 
<Itchy> yup
<FurBall> OOHH... ;)
<FurBall> Ok.. 
<FurBall> Ok.. That does it for regular expressions... ;)
<TDavid> you can also use the m#expressionhere#
<Itchy> cool I sure like these tuesday class's hehe
<TDavid> if furball didn't mention that already
<FurBall> :)
<FurBall> No I didn't... :)
<Itchy> nope you didn't hehe'
<FurBall> OK... Then we are done... :)
<TDavid> yup, itchy, people don't know what they are missing by not coming here :)
<TDavid> a couple hundred dollars per hour worth of information for free! :))
<Itchy> fur sore I know hgow are the friday class's
<FurBall> :)
<Itchy> I moved so been out of touch for a bit 
<FurBall> Hey TD, what's your number again?
<FurBall> (Don't feel like wandering to the website. :))
<Itchy> lol
<TDavid> shame on ya, i want to show you my real time chat interface!
<TDavid> http://www.tdscripts.com/contact.html
<TDavid> try it
<FurBall> Oh wait... :)
<FurBall> Ok...
<TDavid> thank you for coming itchy :))
<Itchy> you bet see you's on friday fur sore 
<FurBall> Oh.. OK.. :)
<FurBall> Great!  See ya there Itchy!
*** Itchy has left #topniche
<FurBall> Ring ring. :)
Session Close: Tue Mar 27 13:23:48 2001