Can't get array to sort.

[Pim]

The problem is that this program crashes:

program Arrays;
 
var
   a: array[1..5] of Integer;
   i, j, tmp: Integer;
 
begin
   a[1] := 23;
   a[2] := 45;
   a[3] := 12;
   a[4] := 56;
   a[5] := 34;
   for i := 1 to 4 do
      for j := i to 5
         if a[j] > a[j + 1] then
            begin
               tmp := a[j];
               a[j] := a[j + 1];
               a[j + 1] := tmp;
            end;
end.

I can't figure out what's wrong with it, it's in the tutorial that way exactly. I've been trying to get it right for a while but I just can't make it work. I'm using the latest Free Pascal compiler. The tutorial can be found here.

Thank You.

[dr4g]

fixed your problem at IRC, but just for the people who are sitting are the code thinking about it, when it's already been fixed :)

Your doing
a[j + 1] := tmp;
on th third last line.

Meaning when j reaches 5, your doing
a[5+1] which is a[6]

Which does NOT exist, as you only created 5 elements for your array at the very start..

Error coded 201 came out of this as you mentioned, which is an outofbounds error.

Confirmation: http://community.freepascal.org:10000/bboards/message?message_id=144869&forum_id=24092

Enjoy.

[ProgrammersTalk]

are you sure that the way it's implemnented in VB:

a: array[1..5] of Integer;

it looks really weird for me... seroiusly.. :-/

btw, ignore this post I'm just looked at it and it's really weird...
but yeah, above me said it correctly :)

[PeterATCook]

Your code has a fundemental floor as pointed out by pim your code

var
a: array[1..5] of Integer;
   i, j, tmp: Integer;

begin
   a[1] := 23;
   a[2] := 45;
   a[3] := 12;
   a[4] := 56;
   a[5] := 34;
   // old code
   //for i := 1 to 4 do
   // new line of code next
   for i := 5 Downto 1 do
   // this new line counts down thru the array not up thru it
      for j := i to 4 do
         if a[j] > a[j + 1] then
            begin
               tmp := a[j];
               a[j] := a[j + 1];
               a[j + 1] := tmp;
            end;
end;

The above code works. But i have not tested it agaist other array lists. There are severl well written sort routines for delphi / Pascal that you should be able to find on the net

[milica.djekic]

Please try this. (I have defined an array as global variable.)

procedure TForm1.Button1Click(Sender: TObject);

var
i, j, tmp: Integer;

begin
for i := 1 to Limit do
for j := i + 1 to Limit do
if a > a[j] then
begin
tmp := a;
a := a[j];
a[j] := tmp;
end;
end;

[Ionelul]

Hi,

I see that you try to do a Bubble sort. The correct algorith is :

program Arrays;
 
var
   a: array[1..5] of Integer;
   i, j, tmp: Integer;
 
begin
   a[1] := 23;
   a[2] := 45;
   a[3] := 12;
   a[4] := 56;
   a[5] := 34;
   for i := 1 to 4 do // for i := 1 to n - 1 do
      for j := i + 1 to 5 //for j := i + 1 to n do
         if a[i] > a[j] then 
            begin
               tmp := a[i];
               a[i] := a[j];
               a[j] := tmp;
            end;
end.

Ionut