PERL Miscellaneous - regex problem with with '|'

Author

regex problem with with '|'

Sharif Islam

2004-07-28, 9:01 pm

I know this is something very simple, but I can't get the right pattern.

#!/usr/bin/perl -w
use strict;
my @array;

@array=('http://www.url.com?db=hph&db=xyz&jid=ABC%22','http://www.direct.asp?db=npx&db=uib&jn=%22PAW%22',
'http://www.www.com?db=abc&jid=HTY');

print "@array\n";
foreach (@array) {
my @newurl = /db=(.{3})/g ;
my @code1 = /jn|jid=([^%22]{3})/ ;
print @newurl;
print @code1;
print "\n";

}
___OUTPUT___
# perl match.pl
http://www.url?db=hph&db=xyz&jid=ABC%22
http://www.direct.asp?db=npx&db=uib&jn=%22PAW%22
http://www.www.com?db=abc&jid=HTY
hphxyzABC
Use of uninitialized value in print at match.pl line 14.
npxuib
abcHTY
____END OUTPUT___

I want hphxyzABC
npxuibPAW
abcHTY
Why the jn or jid part not working?
Thanks,

--
Sharif

Greg Bacon

2004-07-28, 9:01 pm

In article <ce5via$ju6$1@news.ks.uiuc.edu>,
Sharif Islam <mislam@uiuc.edu> wrote:

: [...]
: I want hphxyzABC
: npxuibPAW
: abcHTY

Remember that you need to group the alternatives when that's what
you mean:

$ cat try
#! /usr/local/bin/perl

use warnings;
use strict;

my @array = (
'http://www.url.com?db=hph&db=xyz&jid=ABC%22',
'http://www.direct.asp?db=npx&db=uib&jn=%22PAW%22',
'http://www.www.com?db=abc&jid=HTY',
);

$" = "]["; # mjd's array printing trick
for (@array) {
print "$_ matches:\n";

my @newurl = /db=(.{3})/g;
my @code1 = /(?:jn|jid)=(?:%22)?(.{3})/g;

print " \@newurl = [@newurl]\n";
print " \@code1 = [@code1]\n";
}
[gbacon@cslwww gbacon]$ ./try
http://www.url.com?db=hph&db=xyz&jid=ABC%22 matches:
@newurl = [hph][xyz]
@code1 = [ABC]
http://www.direct.asp?db=npx&db=uib&jn=%22PAW%22 matches:
@newurl = [npx][uib]
@code1 = [PAW]
http://www.www.com?db=abc&jid=HTY matches:
@newurl = [abc]
@code1 = [HTY]

Hope this helps,
Greg
--
... history consists of a series of swindles, in which the masses are
first lured into revolt by the promise of Utopia, and then, when they
have done their job, enslaved over again by new masters.
-- George Orwell

Joe Smith

2004-07-28, 9:01 pm

Sharif Islam wrote:

> I know this is something very simple, but I can't get the right pattern.

> my @code1 = /jn|jid=([^%22]{3})/ ;

You've got a misunderstanding there. Inside of square brackets, "^" means
a negation of the character class that follows, not beginning of string.

/[^%22]{3}/ is the same as /[^2%]{3}/;
it matches any three characters that are not "%" and not "2".
You'll need to use parens, as Greg Bacon showed.
-Joe

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