#!/usr/bin/perl

use strict;
use warnings;

my $student_file='student.txt';
my $database_file='datenbank.txt';

print "Geben sie die Input-Datei ein : ";
my $kyd = <STDIN>;
chomp $kyd;


my %student;

open(my $fh, '<', $student_file) or die("Can't open $student_file $!\n");
while(<$fh>)
{
  chomp;
  #               <MatrikelNr>\t<Name>
  $student{$1} = $2 if(/^(\d+)\t(.+)$/);
}
close($fh);

open(my $db, '<', $database_file) or die("Can't open $database_file $!\n");

print "Class Auswahl: \n";

my %seen;

while(<$db>)
{
  chomp;
  if(/$kyd\t(\d*)/i && !$seen{$1})
  {
    $seen{$1} = 1;
    print "$1 $student{$1}\n";
  }
}

close($db);