Unable to retrieve the string bist_top

suvendra123 has asked for the wisdom of the Perl Monks concerning the following question:

I have a file abc.txt which contains below three lines

parameter,value

controller_name,bist_top_ctrl

support_18n,yes

I want to extract the string bist_top_ctrl

from this file

My code is below xyz.pl

use strict;
use warnings;



open(my $in, '<', $ARGV[0]) or die "Unable to open  for read: $!";

while (my $line = <$in>) {



 while ( $line =~ /\controller_name,\s+(\w+)/g ) {
     my $fourth = $1;

print "$fourth";

  }
}


close $in;
[download]

Command to run :- perl xyz.pl abc.txt

I am not getting the string "bist_top_ctrl" at output

Where is the mistake ?

Comment on Unable to retrieve the string bist_top_ctrl from a file Download Code

Replies are listed 'Best First'.
Re: Unable to retrieve the string bist_top_ctrl from a file by jo37 (Curate) on May 22, 2021 at 13:18 UTC
use `\s*` instead of `\s+`. Greetings, -jo `$gryYup$d0ylprbpriprrYpkJl2xyl~rzg??P~5lp2hyl0p$`	[reply] [d/l] [select]
Re: Unable to retrieve the string bist_top_ctrl from a file by kcott (Archbishop) on May 22, 2021 at 14:28 UTC
In addition to what ++jo37 advised, the regex should probably start with `/^c`; not `/\c` end with `)$/`; not `)/g` See perlretut (tutorial) then perlre (details). — Ken	[reply] [d/l] [select]
Re: Unable to retrieve the string bist_top_ctrl from a file by AnomalousMonk (Archbishop) on May 22, 2021 at 15:24 UTC
`while ( $line =~ /\controller_name,\s+(\w+)/g ) { my $fourth = $1; print "$fourth"; }` [download] Also, this loop is rather suspect (and not just because of the rather bizarre indentation). Why not just use an `if`-conditional to do the extraction and printing? Then you won't be forced to use the `/g` modifier to keep the `while`-loop from running forever. `Win8 Strawberry 5.8.9.5 (32) Sat 05/22/2021 11:10:41 C:\@Work\Perl\monks >perl -Mstrict -Mwarnings my $line = "controller_name,bist_top_ctrl\n"; if ($line =~ /controller_name,\s*(\w+)/) { my $fourth = $1; print "'$fourth' \n"; } ^Z 'bist_top_ctrl'` [download] Give a man a fish: `<%-{-{-{-<`	[reply] [d/l] [select]
Re: Unable to retrieve the string bist_top_ctrl from a file by hrcerq (Monk) on May 22, 2021 at 15:55 UTC
Hi, aside from the other suggestions, you could also use split instead of a regex with a capture group, supposing this file will always be structured as a two-column CSV. `while (my $line = <$in>) { my @fields = split /,/, $line; if ($fields[0] = "controller_name") { $fourth = $fields[1]; } }` [download] It could be further improved, but it's just so you get the picture. Update: The fields variable had the wrong sigil and wasn't lexical. Now corrected. return on_success() or die;	[reply] [d/l]