use Tk;

$window = MainWindow->new(-width=> '0m',-title=> 'Umrechnung');

$oben = $window->Frame->pack();
$titel = $oben->Label(-text=>"Programm für die Umrechnung von Grad Celsius in Kelvin und Fahrenheit.")->pack();

$clean = $window->Frame->pack();
$empty = $clean->Label(-text=>"")->pack();

$window->Label(-text=>'Anfangswert:')->pack();

$eingabe = $window->Text(-width=>20,-height=>1,-borderwidth=> '1m',-cursor=> 'left_side',-background=> 'white',-font=>'courierb12',
-foreground=> 'black')->pack();

$window->Label(-text=>'Endwert:')->pack();
$eingabe2 = $window->Text(-width=>20,-height=>1,-borderwidth=> '1m',-cursor=> 'left_side',-background=> 'white',-font=>'courierb12',
-foreground=> 'black')->pack();

$clean2 = $window->Frame->pack();
$empty2 = $clean2->Label(-text=>"")->pack();

$window->Label(-text=>'Celsius                                        Fahrenheit                                        Kelvin', -font=>'courierb 10 bold' )->pack();
$ausgabe = $window->Text(-width=>60,-height=>10,-borderwidth=> '0m',-cursor=> 'left_side',-background=> 'white',-font=>'courierb 12',
-foreground=> 'black')->pack();

$bottom_frame = $window->Frame()->pack(-side=>'bottom', -pady=>10);
 
$bottom_frame->Button(  -text=>'Alles zeigen',
                        -command=>\&rechnen)->pack(-side=>'left');
                                                
$bottom_frame->Button(  -text => "Alles löschen",
                        -command=>\&loeschen)->pack(-side=>'left');

$bottom_frame->Button(  -text => "Beenden",
                        -command=> sub {exit 0})->pack(-side=>'left');

MainLoop;

sub rechnen {
    my $anfang = $eingabe->Contents;
    my $k = (($anfang * 9)  /5 ) +32;
    my $f = $anfang + 273.15;
    $ausgabe->Contents("Fahrenheit: $k\nKelvin: $f");
}

sub loeschen {
    $ausgabe->Contents('');
}