21 Strings library [strings]

21.4 Class template basic_string [basic.string]

21.4.8 basic_string non-member functions [string.nonmembers]

21.4.8.8 swap [string.special]

template<class charT, class traits, class Allocator> void swap(basic_string<charT,traits,Allocator>& lhs, basic_string<charT,traits,Allocator>& rhs) noexcept;

Effects: lhs.swap(rhs);