STL map doesn't add a pair after removing the first pairs

Answer 1

Well you are keying on the size of the map, this seems like it may cause your problems.

So if you have 3 things in the map you will have

  1 => Obj1
  2 => Obj2
  3 => Obj3

if you remove one of these elements, say at 1, you will have

  2 => Obj2
  3 => Obj3

then later you go to insert, and set the key to "size() + 1", size will return 2, and you will try to insert at key 2 + 1 == 3. 3 is already taken. So it will either get overriden or fail (not sure how your find is working above).

Instead of inserting at the size + 1, I would check the last key and increment by 1 if thats how you want to manage the key.

Answer 2

Your question does not make any sense.