Erase an element.
iterator erase( const_iterator pos);
Remove the element pointed to by
which must be valid and dereferenceable. Thus the
iterator (which is valid but cannot be dereferenced) cannot be used as
a value for
and iterators to the erased element are invalidated. Other iterators
and references are not invalidated.
Constant on average, worst case linear in
An iterator following the last removed element.
An iterator pointing to the element to be removed.