std::hash (std::string, std::wstring, std::u16string, std::u32string, std::pmr::string, std::pmr::wstring, std::pmr::u16string, std::pmr::u32string)

< cpp‎ | string‎ | basic string
Non-member functions
Helper classes
Deduction guides(C++17)
Defined in header <string>
template<> struct hash<std::string>;

template<> struct hash<std::wstring>;
template<> struct hash<std::u16string>;

template<> struct hash<std::u32string>;
(since C++11)
template<> struct hash<std::pmr::string>;

template<> struct hash<std::pmr::wstring>;
template<> struct hash<std::pmr::u16string>;

template<> struct hash<std::pmr::u32string>;
(since C++20)

The template specializations of std::hash for the various string classes allow users to obtain hashes of strings.

These hashes equal the hashes of corresponding std::basic_string_view classes: If S is one of these 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)).

(since C++17)


The following code shows one possible output of a hash function used on a string:

#include <iostream>
#include <string>
#include <functional>
int main()
    std::string s = "Stand back! I've got jimmies!";
    std::hash<std::string> hash_fn;
    size_t hash = hash_fn(s);
    std::cout << hash << '\n';



See also

hash function object
(class template)