#!/usr/bin/perl -w
use strict;
my %myhash=();
my $myhash;

open(DATA_LIST, "<data_list") or die "Can't open data_list to read!: $!\n";
while (<DATA_LIST>){
  chomp;
  my ($Line,$Filed,$Dvalue)=split/\t/;
  #open(MYHASH, ">myhash") or die "Can't open myhash to write : $!\n";

  # vladb: reading data from file 'file_data' into %myhash hash..
  do_hash("file_data");

  # vladb: are you absolutely sure value stored in $Line
  # was also found in the 'file_data' file which was used to
  # initialize the %myhash hash structure?
  print $myhash{$Line},"\n";  # *** vladb: move this line inside the following if(..){} block.

  if (exists $myhash{$Line}){
    print $Filed,"\t ",$Dvalue,"\t", $myhash{$Line},"\n";
  }
} 

sub do_hash {
  my ($filename)=@_;
  open(FH, $filename) or die "Can't open $filename: $!\n";
  while(<FH>){
    chomp;
    my ($Name, $Data)=split/\t/;
    $myhash{$Name}=$Data;
  }
  close FH;
}