Const reference qualifier on a member function [duplicate]
问题 This question already has answers here : What does the single ampersand after the parameter list of a member function declaration mean? (3 answers) Closed 5 years ago . I have seen in an anwser there: Is returning by rvalue reference more efficient? The member function definition: Beta_ab const& getAB() const& { return ab; } I am familiar with the cv-qualifier ( const ) on member functions, but not const& . What does the last const& mean? 回答1: The & is a ref-qualifier . Ref-qualifiers are new