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Re: Store and match
by prasadbabu (Prior) on Aug 11, 2009 at 06:26 UTC
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The mistake you have done is you have not stored the current line in variable $x. Also \w+ will match only 'note_values' and not the remaining string 'note_values,notes_values2
' as it contains ',' in between.
The below code will meet your requirement. Also refer perlre to learn how to store the matched value in variables.
while($x=<DATA>){
if ($x =~ /^\[Note\](.+)$/){
$var = $1; #store in a variable
print $var;
}
}
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#!/usr/bin/perl
while($x=<DATA>){
if ($x =~ /^\[Note\](.+)$/){
$var = $1; #store in a variable
print $var;
}
}
__DATA__
[Note]
note_values,notes_values2
[Book]
novels,magazines
[Note]
note_values,notes_values3
Hi,
if the values are as above,
then how to print the values of Note.
If the values of Note has "note_values", then how to count the number of occurence | [reply]
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use strict;
use warnings;
my $prev = 0;
my $total = 0;
while(my $x = <DATA>){
$prev = 1 if ($x =~ /^\[Note\]$/);
my $count = 0;
if (($x =~ /note_values/) && $prev){
$count = $x =~ s/(note_values)/$1/g; #if more than one note_va
+lues present in a line
$prev = 0;
}
$total = $total + $count;
}
print "Number of occurence: $total";
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Re: Store and match
by vinoth.ree (Monsignor) on Aug 11, 2009 at 07:26 UTC
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As prasadbabu given correct answer I believe.
As of my understand you want the last potion from the line which begins with Note. I also done this with split function.
use strict;
use warnings;
my $x;
while($x=<DATA>){
chomp($x);
if ($x =~ /^\[Note\]/){
my $find=(split(/\,/,$x))[-1] ;
print "$find\n";
+
+
}
}
__DATA__
[Note]note_values,notes_values2
[Book]novels,magazines
[Note]note_values,notes_values56
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Re: Store and match
by Bloodnok (Vicar) on Aug 11, 2009 at 13:18 UTC
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In general, you might like to have a look at the format, also the assignment in while ($_=<DATA>)... is superfluous - while (<DATA>)... does exactly the same thing.
As to the exact problem, using strictures would have given you a clue to solving the problem since, assuming you rewrite $x =~ /^\[Note\](\w+)/; to my $x =~ /^\[Note\](\w+)/; (to remove the undeclared variable error that would otherwise ensue), you would have seen a use of uninitialised value in pattern match... error, the solution to which is (my $x = $_) =~ /^\[Note\](\w+)/;.
Having done all that, you can then go on to solve the problem of extracting the value from the field - maybe along the lines of $x =~ s/[^,]*,//;, so the final code should, IMO, look like:
<p>#!/usr/bin/perl
use warnings;
use strict;
while (<DATA>){
(my $x = $_) =~ /^\[Note\](\w+)/;
$x =~ s/[^,]*,//;
print $x;
}
__DATA__
[Note]note_values,notes_values2
[Book]novels,magazines
Which generates:
$ perl tst.pl
notes_values2
magazines
$
As required. It then becomes a trivial exercise to ignore lines of no interest...
A user level that continues to overstate my experience :-))
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Re: Store and match
by cdarke (Prior) on Aug 11, 2009 at 07:50 UTC
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Your data line is read into $_, but you are using $x for the match. To get separate the parts: # $_ is the default buffer and pattern space
while(<DATA>){
/^(\[\w+\])(.+)/;
my $prefix = $1;
my $values = $2;
print "prefix:$prefix values:$values\n";
}
Not sure if you require the square brackets in your result or not. Note that \w does not include a comma, and that there are, of course, many other ways to do it. | [reply]
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Re: Store and match
by Utilitarian (Vicar) on Aug 11, 2009 at 07:56 UTC
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#!/usr/bin/perl
use strict;
use warnings;
while($_=<DATA>){
if (/^\[Note\]\w+,(\w+)/){
my $x =$1;
print "$x\n";
}
}
__DATA__
[Note]note_values,notes_values2
[Book]novels,magazines
A couple of comments:
- use strict and use warnings even on a little script they will often catch a simple error that your eyes will gloss over "seeing what I meant to write"
- $x=~/^\[Note\](\w+)/; tries to match the regex in $x
- I think it does what you're looking for, if I read your question correctly
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Re: Store and match
by bichonfrise74 (Vicar) on Aug 11, 2009 at 16:54 UTC
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#!/usr/bin/perl
use strict;
while(<DATA>){
my ($x) = $_ =~ /^\[Note\](.*)/;
print $x if ( defined( $x ) );
}
__DATA__
[Note]note_values,notes_values2
[Book]novels,magazines
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Re: Store and match
by Marshall (Canon) on Aug 11, 2009 at 22:31 UTC
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Your data looks a lot like a ".ini" or "config" file. I suggest looking at something like use Config::INI::Reader, there are other config readers.
Update: I don't think that I was clear at all. Sorry. The idea is to put the data into a standard file format and use one of the Perl modules to parse it for you. I've used some of these .ini or .config file parsers and they work very well. I think it is something to be seriously considered. A file could look like this:
[Note]
note_value1
notes_value2
or
[Note]
values = value1, value2
[Book]
novels = 211
magazines = "Scientific American", "Economist"
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