Question

Can anyone please help me with writing a Perl script which can take as input 5 text files and create a new text file with merging each row of all 5 files.
Should this be done by opening 5 read streams at a time or like java some random file reader is available in Perl ?

Thank You!

Answer 1

This program expects a list of files on the command line (or, on Unix systems, a wildcard file spec). It creates an array of filehandles @fh for these files and then reads from each of them in turn, printing the merged data to STDOUT

use strict;
use warnings;

my @fh;
for (@ARGV) {
  open my $fh, '<', $_ or die "Unable to open '$_' for reading: $!";
  push @fh, $fh;
}

while (grep { not eof } @fh) {
  for my $fh (@fh) {
    if (defined(my $line = <$fh>)) {
      chomp $line;
      print "$line\n";
    }
  }
}