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storing matches

PGScooter
stranger

Apr 20, 2007, 1:13 PM

Post #1 of 6 (8873 views)

storing matches	Can't Post

Hi, I have a few questions about storing matches found with regexes. The "error" I get is that I get the number of results not returned, not the results. I think my problem has to do with scalars, but I'm not sure how to switch modes per se.

The following piece of code works, but I am curious why the ones below do not.

Code

  
 
@pronunciation=($definition=~/Pronunciation\[*\]/g);

How can I store just the first match? The following do not work:

Code

@pronunciation=($definition=~/Pronunciation\[*\]/);  
 
   
 
$pronunciation=($definition=~/Pronunciation\[*\]/);

How can I substitute and store what was substituted? The following does not work:

Code

@pronunciation=($definition=~s/Pronunciation\[*\]/OUT/g);

Thank you!

Scott
The more you teach me, the more I learn. The more I learn, the more I teach.

osmodius
Novice

Apr 21, 2007, 4:02 PM

Post #2 of 6 (8864 views)

Re: [PGScooter] storing matches [In reply to]	Can't Post

Well, in response to your first question - why do they not work? It's because in a scalar context, the match operator (m//) will return true or false, and NOT the string that triggered the match. The following code will work,

Code

if($definition =~ m/(Pronunciation\[*\])/){  
  $pronunciation = $1; 
 }

And for the second question - why does it not work? Because the substitute operator (s///) returns the number of strings substituted, and not the strings that were substituted. To get around this, you can do the following:

Code

while($definition =~ s/(Pronunciation\[*\])/OUT/g){ 
  push(@pronunciation, $1); 
 }

Need some real-time help? Shove admin@ub3r.net on yer MSN.

PGScooter
stranger

Apr 21, 2007, 9:58 PM

Post #3 of 6 (8861 views)

Re: [osmodius] storing matches [In reply to]	Can't Post

Osmodius,

Thank you for the help and the explanation. Although I still don't quite understand why the one I posted that does work is not in scalar context, that clears up some things.

Thanks,

Scott
The more you teach me, the more I learn. The more I learn, the more I teach.

osmodius
Novice

Apr 22, 2007, 4:04 AM

Post #4 of 6 (8858 views)

Re: [PGScooter] storing matches [In reply to]	Can't Post

In response to your further question - why is it not in scalar context? Because you are assigning it to an array. Therefore, the assignment operator is waiting on a rvalue with a list context. And bingo, it gets one! The match operator (m//) returns the list of strings matched WHEN used in conjunction with the /g modifier.

Hope that clears things up for you.

Need some real-time help? Shove admin@ub3r.net on yer MSN.

PGScooter
stranger

Apr 22, 2007, 3:29 PM

Post #5 of 6 (8852 views)

Re: [osmodius] storing matches [In reply to]	Can't Post

Yes, osmodius, that does help, I just have to contemplate this stuff a little bit and let it sink it :)

Thanks
The more you teach me, the more I learn. The more I learn, the more I teach.

KevinR
Veteran

Apr 22, 2007, 7:47 PM

Post #6 of 6 (8849 views)

Re: [PGScooter] storing matches [In reply to]	Can't Post

Some of the stuff here may help although it's not a thorough regexp tutorial:

http://perldoc.perl.org/perlrequick.html
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