Quick Sort (Turbo Pascal)

{ Quick Sort
  g0tch4.blogspot.com }

uses crt;
const
 max = 10;
type
 arr = array [1..max] of byte;
 var
    data :arr;
    x,y :byte;

procedure input;
begin
    clrscr;
    writeln ('Program Sorting Data dengan Quick Sort');
    writeln;
    writeln ('Inputkan 10 buah bilangan :');
    writeln ('---------------------------');
    for x:= 1 to max do
    begin
         write ('Data ke-',x,'= '); readln (data[x]);
    end;
    clrscr;
    writeln ('Data Sebelum diurutkan: ');
    writeln ('---------------------------');
    for x:= 1 to max do
         write (data[x],' ');
         writeln;writeln;
         writeln('Data Sesudah diurutkan:');
         writeln('---------------------------');
end;

procedure change(var a,b :byte);
var c : byte;
begin
    c:=a; a:=b; b:=c;
end;

procedure asc_quick(l,r :integer);
var
    mid,j,k :integer;
begin
    j:=l; k:=r; mid:=(l+r) div 2;
    repeat
         while data [j] <> data [mid] do dec(k);
         if j<=k then           begin                change (data [j],data[k]);                inc(j); dec(k);           end;      until j>k;
    if l <> data[mid]  do inc(j);
         while data [k] <>k;
    if l < k then desc_quick(l,k);
    if j < r then desc_quick(j,r);
end;

procedure output;
begin
    for x :=1 to max do
         write(data[x],' ');
         writeln;
end;

begin
    input;
    asc_quick(1,max);write('Secara Ascending  : ');
    output;
    desc_quick(1,max);write('Secara Descending : ');
    output;
    readkey;
end.