delete object on a list

[DarkBow]

AAARRRRGGGHHHHH

Ive been scouring the internet for an example of how to remove an object from a Tobjectlist with no luck

for iter3:=0 to obby_list.count-1 do
begin
obj:=obby_list.items[iter3];
obby_list.remove(obj);
end;

this example crashes with exception 'unknown'

Just to clarify it a bit, that code snippet will not work, but Srki_82's code will. The problem is that both Remove and Delete methods remove the the object from the list and move all objects that were behind it in the list 1 position up in the list, i.e, when you remove the first object on position 0, the object on position 1 moves to position 0, the object on position 2 to position 1, etc.

Regarding the memory, as long the property OwnsObjects is true Remove will free the object. Not sure if Delete will.

[Dan]

short and simple:

obby_list.Clear;

this will free all the items and clear the list, assuming the class of obby_list is TObjectList.

[slenkar]

Just to clarify it a bit, that code snippet will not work, but Srki_82's code will. The problem is that both Remove and Delete methods remove the the object from the list and move all objects that were behind it in the list 1 position up in the list, i.e, when you remove the first object on position 0, the object on position 1 moves to position 0, the object on position 2 to position 1, etc.

Regarding the memory, as long the property OwnsObjects is true Remove will free the object. Not sure if Delete will.

thanks both of you, i couldnt find any example of how to remove a single object from a Tobjectlist anywhere

[User137]

It's the same principle with any array. "For" works different in C than pascal. For example:

// This loop would print all numbers 1 to 10... They become like constants for the loop at beginning
num:=10;
for i:=1 to num do begin
  num:=1;
  writeln(inttostr(i));
end;

// Same in C would just print 1
num=10;
for (int i=1; i<=num; i++) {
  num=1;
  printf("%d",i);
}

So you have to restrict what you are deleting from the array or list. Simplest was like mentioned from end to start

for i:=0 to list.count-1 do
  if MarkedForDeletion(list[i]) then list.Delete(i);

But ofc you can do it other ways like:

i:=0;
while (i<list.count) do begin
  if MarkedForDeletion(list[i]) then list.Delete(i)
  else inc(i);
end;

[slenkar]

ohhh so the listcount isnt updated every loop in a FOR loop
but in a WHILE loop it IS updated?

I take it that is a compiler optimisation thingy