From cppreference.com
Defined in header
template<>structhash<std::string_view>;(since C++17)template<>structhash<std::wstring_view>;(since C++17)template<>structhash<std::u8string_view>;(since C++20)template<>structhash<std::u16string_view>;(since C++17)template<>structhash<std::u32string_view>;(since C++17)Template specializations of
for the various view classes for hashing views.
These hashes equal the hashes of corresponding
classes: If S is one of the standard basic_string types, SV is the corresponding string view type, and s is an object of type S, then std::hash<S>()(s)==std::hash<SV>()(SV(s)).
Example
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#include<iostream>#include<string_view>#include<unordered_set>usingnamespacestd::literals;intmain(){std::cout<<"\"A\" #: "<<std::hash<std::string_view>{}("A"sv)<<'\n';std::cout<<"L\"B\" #: "<<std::hash<std::wstring_view>{}(L"B"sv)<<'\n';std::cout<<"u8\"C\" #: "<<std::hash<std::u8string_view>{}(u8"C"sv)<<'\n';std::cout<<"u\"D\" #: "<<std::hash<std::u16string_view>{}(u"D"sv)<<'\n';std::cout<<"U\"E\" #: "<<std::hash<std::u32string_view>{}(U"E"sv)<<'\n';// std::hash for string_view family makes it possible to keep these view-types// in unordered_* associative containers, such as unordered_set. But ensure// the lifespan of referenced strings is no less than lifespan of the container,// i.e. no dangling references occurred.std::unordered_setstars{"Rigel"sv,"Capella"sv,"Vega"sv,"Arcturus"sv};for(std::string_viewconst&s:stars)std::cout<<s<<' ';std::cout<<'\n';}Possible output:
"A" #: 6919333181322027406 L"B" #: 11959850520494268278 u8"C" #: 12432341034569643010 u"D" #: 312659256970442235 U"E" #: 18073225910249204957 Arcturus Vega Capella Rigel See also
(C++11)
hash function object
(class template)