std::vector<T,Allocator>::push_back (3) - Linux Manuals
void push_back( const T& value ); (1)
void push_back( T&& value ); (2) (since C++11)
Appends the given element value to the end of the container.
1) The new element is initialized as a copy of value.
2) value is moved into the new element.
If the new size() is greater than capacity() then all iterators and references (including the past-the-end iterator) are invalidated. Otherwise only the past-the-end iterator is invalidated.
T must meet the requirements of CopyInsertable in order to use overload (1).
T must meet the requirements of MoveInsertable in order to use overload (2).
If an exception is thrown (which can be due to Allocator::allocate() or element copy/move constructor/assignment), this function has no effect (strong exception guarantee).
If T's move constructor is not noexcept and T is not CopyInsertable into *this, vector will use the throwing move constructor. If it throws, the guarantee is waived and the effects are unspecified. (since C++11)
Some implementations also throw std::length_error when push_back causes a reallocation that would exceed max_size, due to implicitly calling an equivalent of reserve(size()+1).
// Run this code
emplace_back constructs an element in-place at the end
pop_back (public member function)