Compares: 
     Swaps: 
Assignments 
 END OF DEMO. ! 
return.chn
%Enter a speed from 1 to 9 (1=slowest)
%or 0 to single step thru program     
 Press spacebar to continue... 
 Press ESC to quit...          
' Press 1-9 to change speeds, 0 to pause
Bad variable number.
(----------------------------------------
'---------------------------------------
Right
Pivot
@Press  Space to continue, ESC to quit, 0-9 to change speeds, or 
 to scroll.
8PROGRAM Quick1( Input, Output );   { Quicksort program }
CONST Size = 20;
&TYPE List = ARRAY[1..Size] OF INTEGER;
&  L: List;      { Array to be sorted }
  K: INTEGER;
%PROCEDURE Swap( VAR X, Y : INTEGER );
VAR Temp:INTEGER;
BEGIN
  Temp := X;
	  X := Y;
  Y := Temp
END;     { Swap }
PROCEDURE QSort(
,      Left,    { Position of first element }
+      Right:   { Position of last element }
       INTEGER
      );
  Up, Down, Pivot: INTEGER;
BEGIN
"              { Partition values }
  Up := Left;
  Down := Right;
9  Pivot := L[ (Left+Right) div 2 ];   { Set pivot value }
  REPEAT
6    WHILE L[Up] < Pivot  DO           { Scan forward }
      Up := Up+1;
7    WHILE Pivot < L[Down]  DO         { Scan backward }
      Down := Down-1;
?    IF  Up <= Down  THEN              { Swap & continue scans }
      BEGIN
        SWAP( L[Up], L[Down] );
        Up := Up+1;
        Down := Down-1
	      END
C  UNTIL  Up > Down;                   { until scan pointers cross }
*              { Sort each partition part }
  IF Left < Down
2    THEN  QSort( Left, Down );  { Sort left part }
  IF Up < Right
2    THEN  QSort( Up, Right );  { Sort right part }
END;     { QSort }
!BEGIN    { Main = QuickSortDemo }
  FOR K := 1 TO Size DO
     L[K] := TRUNC( RANDOM*900 );
  QSort( 1, Size );
END.     { QuickSortDemo }
Bad variable number.