1

For example: 

constexpr T value_or(U&& v) const &

What is & after const?

and sometimes I also see && after const, what is that?

JustWe
  • 4,250
  • 3
  • 39
  • 90
  • 3
    Does this answer your question? [const& , & and && specifiers for member functions in C++](https://stackoverflow.com/questions/28066777/const-and-specifiers-for-member-functions-in-c) – rrswa Mar 19 '20 at 04:13
  • 3
    yes、please mark as duplicated. thanks – JustWe Mar 19 '20 at 04:15

0 Answers0