The [1] in line 12 of Marshall's post refers to the second column in file1 that you want to extract into the hash keys. The first column would be [0]

 my $col2 = (split /\|/, $_)[1];

perhaps this is easier to understand

#!/usr/bin/perl
use strict;
use warnings;
use Data::Dumper;

#@ARGV = ('file1.txt','file2.txt','file3.txt',2,3);
my ($file1, $file2, $file3, $file1col,$file2col) = @ARGV;

my %hash = ();
open my $fh1,'<', $file1 
     or die "Could not open for read $file1 : $!";
while ( my $row = <$fh1> ) {
    chomp $row;
    next if $row =~ /^\s*$/;
 
    # extract the selected column only
    my @fields = split /\|/, $row ;
    my $key = $fields[$file1col-1];
    $key =~ s/^\s+|\s+$//g;# trim spaces
    $hash{$key} = 1;
}
close $fh1;
print Dumper \%hash;

open my $fh2,'<', $file2 
     or die "Could not open for read $file2 : $!";

open my $fh3,'>', $file3 
     or die "Could not open for write $file3 : $!";
     
while ( my $row = <$fh2> ) {
    chomp $row;
    next if $row =~ /^\s*$/g;
 
    # extract the selected column only
    my @fields = split /\|/, $row ;
    my $key = $fields[$file2col-1];
    $key =~ s/^\s+|\s+$//;# trim spaces

    if ( exists $hash{$key} ) {
       print "$row\n";
    }
}

close $fh2;
close $fh3;

[download]
poj

In reply to Re^5: Comparision Utility PERL by poj
in thread Comparision Utility PERL by vighneshmufc

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