Regex to get string until certain string in Perl

user_6124824 0
Viewed 232

I have a string and I want to extract certain part of the string using regex.

Below is my script. I could able to get the expected output. But need to know do we have any alternative way to achieve this.

#!/usr/bin/perl

use strict; use warnings;

my $str = "Network=ABC,Network=10,Node=N360,Slot=3,Unit=R1,Group=RU,DeviceSet=1,Device=2";

if($str =~ m/(.*),Device/){
    print "Out: $1";
} else {
    print "Not matching";
}

If the string contains Device=<anydigit> at the end, then it should not print Device=<anydigit> and rest everything it should print. I am doing this using (.*) expression. Apart from this any alternative we have?

perl regex
4 Answers

I'd tackle it like this:

#!/usr/bin/perl

use strict; 
use warnings;

use Data::Dumper;

my $str = "Network=ABC,Network=10,Node=N360,Slot=3,Unit=R1,Group=RU,DeviceSet=1,Device=2";

my @field_order = ( $str =~ m/(\w+)=/g);
my %value_of = ($str =~ m/(\w+)=(\w+)/g);

print Dumper \%value_of;

print "Contains Device of $value_of{'Device'}\n" if defined $value_of{'Device'};

pop ( @field_order ) if ( $field_order[-1] eq "Device" ); #discard trailing 'Device' field. 

print Dumper \@field_order;


#Splice together your hash, without including 'Device' on the end. 
print join ",", map { $_ . "=". $value_of{$_}  } @field_order;

In doing this you parse your string into a data structure, and can work with the separate keys and values,

user_25661980

If you simply want to remove the Device=<N> anywhere in the string, including at the end, you can use this replacement:

my $str = "Network=ABC,Network=10,Node=N360,Slot=3,Unit=R1,Group=RU,DeviceSet=1,Device=2";
$str =~ s/,Device=\d+//;
# result: "Network=ABC,Network=10,Node=N360,Slot=3,Unit=R1,Group=RU,DeviceSet=1"

Explanation:

  • search: ,Device=\d+
  • replace: (empty, e.g. remove the match)

This regex is more defensive. If however you'd like to remove the pattern only at the end, append a $ to the regex:

$str =~ s/,Device=\d+$//;
user_74754500

May be this will help

    if($str =~ m/(.*?)\,Device\b/){
       print "Out: $1";
    } else {
       print "Not matching";
    }

Here, (.*?) will find the first set string of Device word. Also, we need to set the boundary for the Word.

user_127306610

First, does you pattern actually match what you want? You want to find Device=<digit> at the end. That's not what your pattern does though. You don't include the information about the digit or the end of line. Anchors are important in these situations:

 /
 ,       # Start of final field to anchor this to a whole column
 Device
 =
 [0-9]
 $       # end of line
 /x

Second, the substitution operation tells you the number of substitutions it made. If it made a substitution, that's a line you want, so print the modified line:

if( $var =~ s/.../\n/ ) {
   print $var
   }
else {
   print "No match\n";
   }
brian_d_foy_27661760
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