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std::hash<std::thread::id>

From cppreference.com
< cpp‎ | thread‎ | thread‎ | id
 
 
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std::hash<std::thread::id>
 
Defined in header <thread>
template<> struct hash<std::thread::id>;
(since C++11)

The template specialization of std::hash for the std::thread::id class allows users to obtain hashes of the identifiers of threads.

[edit] Example

#include <chrono>
#include <iostream>
#include <thread>
#include <vector>
using namespace std::chrono_literals;
 
void foo()
{
    std::this_thread::sleep_for(10ms);
}
 
int main()
{
    std::vector<std::thread> v;
    for (int n = 0; n < 4; ++n)
        v.emplace_back(foo);
 
    std::hash<std::thread::id> hasher;
    for (auto& t : v)
    {
        std::cout << "thread " << t.get_id() << " hashes to "
                  << hasher(t.get_id()) << '\n';
        t.join();
    }
}

Possible output:

thread 139786440144640 hashes to 8905351942358389397
thread 139786431751936 hashes to 9222844670065909738
thread 139786423359232 hashes to 18199000599186780501
thread 139786414966528 hashes to 15386662774029264672

[edit] See also

(C++11)
hash function object
(class template) [edit]