push_back vs emplace_back?

Question

I'm a bit confused regarding the difference between `push_back` and `emplace_back`. void emplace_back(Type&& _Val); void push_back(const Type& _Val); void push_back(Type&& _Val); As there is a `push_back` overload taking a rvalue reference I don't quite see what the purpose of `emplace_back` becomes?

Answer 1

The short answer is that std::vector emplace_back forwards parameters to the constructor and avoids any extra copy or move operation required when using std::vector push_back. push_back may construct a temporary object, which then gets moved into the vector; whereas, emplace_back just forwards the argument(s) and constructs it directly in place with no copies or moves needed.

I hope this makes sense?