c++ - In Lists, is remove same as erase? -

those 2 sample examples of trying say.

first example.

std::list<someclass*> somelist; // have defined someclass m 

1. method remove

   std::remove(somelist.begin(), somelist.end(), m); 

2. method erase

   auto = std::find(somelist.begin(), somelist.end(), m); if (it != somelist.end()) {     somelist.erase(it); } 

question: there difference in behavior or performance?

---

second example.

well actual purpose of asking question,

std::list<someclass*> somelist; someclass* m = nullptr; 

using same methods first example, behavior, using both methods.

here standard says:

• erase:

  iterator erase(const_iterator position); iterator erase(const_iterator first, const_iterator last); 

  invalidates iterators , references erased elements.

• remove:

  void remove(const t& value); template <class predicate> void remove_if(predicate pred); 

  erases elements in list referred list iterator i for following conditions hold: *i == value, pred(*i) != false. invalidates iterators , references erased elements.

if don't have iterator or couple of iterators used erase , have rearrange element(s) first, using remove better choice.

note remove drop elements matching predicate , complexity is:

exactly size() applications of corresponding predicate

on other side, find has still complexity o(n), stops when finds first occurrence satisfies condition.
in particular, it's complexity defined standard as:

at most last - first applications of corresponding predicate.

where following signature:

template<class inputiterator, class t> inputiterator find(inputiterator first, inputiterator last, const t& value); 

differences in behavior: use first proposal drop elements matching predicate, use second proposal (find and) drop first element matching predicate.
differences in performance: same complexity, in worst case won't have benefit (well, in best case have benefits on large containers, o(n) irrelevant if n equal 100).

to reply last question, if want remove nullptrs list , happen there more one, prefer remove instead of find/erase.