my $state = 'start';
my $crit = 3;

sub getDatensatz{
  my ($entry) = @_;
  my $bool = 0;
  my $set = '';
  my @steigend;
  for my $line(split(/\r?\n/,$entry)){
    chomp $line;
    my $wert = (split(/\s+/,$line))[-1];

    if ($wert >= $crit and $state ne 'high') {
        $state = 'high';
    }
    elsif ($wert < $crit and $state ne 'low') {
        if ($state eq 'high') {
            $bool = 1;
        }
        $state = 'low';
    }

    unless($bool){
      push(@steigend,$line);
    }
    else{
      $set .= $line."\n";
    }
  }
  $set .= $_."\n" for(@steigend);
  $set .= "\n\n";
  return $set;
}

Use of uninitialized value in numeric lt (<) at ./sortier_neu.pl line 55, <$fh> line 9921.
Use of uninitialized value in numeric ge (>=) at ./sortier_neu.pl line 55, <$fh> line 9921.

if ($wert >= $crit and $state ne 'high') {