TStringList to Array

[BubikolRamios]

Code: Pascal  [Select][+][-]

1. var
2.   sa:TStringList;
3.   sb:Array of TStringList;
4.   i: integer;
5. begin
6.   sa := TStringList.Create;
7.   sa.Clear;
8.   sa.Add('1');
9.   sa.Add('2');
10.   SetLength(sb,Length(sb)+1);
11.   sb[0] := sa;
12.   SynEdit1.Lines.add(sb[0].Text);
13.  
14.   sa.Clear;
15.   sa.Add('3');
16.   sa.Add('4');
17.   SetLength(sb,Length(sb)+1);
18.   sb[1] :=  sa;
19.   SynEdit1.Lines.add(sb[1].Text);
20.  
21.   for i := 0 to Length(sb)-1 do
22.   begin
23.        SynEdit1.Lines.add(sb[i].Text);
24.   end;    
25.  

Out:
12
34
34
34

What happens in loop ?  Last two outputs are expected to be
12
34

[molly]

You create one stringlist

Code: [Select]

6.  sa := TStringList.Create;

Then you add values to it:

Code: [Select]

7.  sa.Add('1');
8.  sa.Add('2');

then you set the length of the array:

Code: [Select]

9.  SetLength(sb,Length(sb)+1);

you set the first entry of the array to sa

Code: [Select]

10. sb[0] := sa;

then you clear that same sa stringlist (all values cleared from that list):

Code: [Select]

11.  sa.Clear;

then you add two values to sa:

Code: [Select]

12. sa.Add('3');
13. sa.Add('4');

then you 'expand' the array again to make room for...

Code: [Select]

14.  SetLength(sb,Length(sb)+1);

... yet another entry of the same sa stringlist class.

Code: [Select]

15.   sb[1] :=  sa;

1. Storing a stringlist into an array does not automagically creates a copy for you
2. Using the same reference to the same stringlist means that you are still manipulating that same stringlist (and thus its contents).

PS: you changed the code so my analyses does not match your code accurately anymore.

[BubikolRamios]

Yeah, changed a bit, important thing in changed is this:

Code: Pascal  [Select][+][-]

1. SynEdit1.Lines.add(sb[0].Text);
2. SynEdit1.Lines.add(sb[1].Text);
3. for i := 0 to Length(sb)-1 do
4. begin
5.        SynEdit1.Lines.add(sb[i].Text);
6. end;
7.  

out:
12
34
34
34

So, it looks like the stuff is there, before loop, inside sb
and then in loop it is not there any more.

Using the same reference to the same stringlist means that you are still manipulating that same stringlist (and thus its contents).

OK, got it.
Thanks.