Selection Sort in PASCAL

16 Sep 2010

PROGRAM Selection_Sort;

CONST len = 12;

TYPE intarray = ARRAY[1..len] OF INTEGER;
 
FUNCTION ssort (A: intarray): intarray;
VAR
 at, i, j, smaller, tmp: integer;
 newarray: intarray;
BEGIN
  { copy array }
  FOR i:=1 TO len DO
   newarray[i] := A[i];

  { sort }
  FOR i:=1 TO len-1 DO
  BEGIN
   smaller := newarray[i];
   at   := i;
   FOR j:=i+1 TO len DO
   BEGIN
    IF newarray[j] < smaller THEN
    BEGIN
     smaller := newarray[j];
     at  := j;
    END
   END; { FOR j:=i+1 }

   IF newarray[i] > smaller THEN
   BEGIN { swap } 
    tmp := newarray[i];
    newarray[i] := smaller;
    newarray[at] := tmp;
   END
  END; { FOR i:= 0 }
  ssort := newarray;
END;

{ MAIN }
VAR
 a1, a2: intarray;
 buf, i: integer;

BEGIN
 { read array }
 FOR i:=1 TO len DO
 BEGIN
  writeln ('Enter a number');
  readln (buf);
  a1[i] := buf; 
 END;

 { print a1 }
 FOR i:=1 TO len DO
 BEGIN
  write(a1[i], ' ');
 END;
 writeln;

 { sort }
 a2 := ssort (a1);

 { print sorted a2}
 FOR i:=1 TO len DO
 BEGIN
  write(a2[i], ' ');
 END;
 writeln;
END.