std::thread::joinable
From cppreference.com
bool joinable() const noexcept; |
(since C++11) | |
Checks if the std::thread
object identifies an active thread of execution. Specifically, returns true if get_id() != std::thread::id(). So a default constructed thread
is not joinable.
A thread that has finished executing code, but has not yet been joined is still considered an active thread of execution and is therefore joinable.
Contents |
[edit] Parameters
(none)
[edit] Return value
true if the std::thread
object identifies an active thread of execution, false otherwise.
[edit] Example
Run this code
#include <chrono> #include <iostream> #include <thread> using namespace std::chrono_literals; void foo() { std::this_thread::sleep_for(500ms); } int main() { std::cout << std::boolalpha; std::thread t; std::cout << "before starting, joinable: " << t.joinable() << '\n'; t = std::thread{foo}; std::cout << "after starting, joinable: " << t.joinable() << '\n'; t.join(); std::cout << "after joining, joinable: " << t.joinable() << '\n'; t = std::thread{foo}; t.detach(); std::cout << "after detaching, joinable: " << t.joinable() << '\n'; std::this_thread::sleep_for(1500ms); }
Output:
before starting, joinable: false after starting, joinable: true after joining, joinable: false after detaching, joinable: false
[edit] References
- C++23 standard (ISO/IEC 14882:2024):
- 33.4.3.6 Members [thread.thread.member]
- C++20 standard (ISO/IEC 14882:2020):
- 32.4.2.5 Members [thread.thread.member]
- C++17 standard (ISO/IEC 14882:2017):
- 33.3.2.5 thread members [thread.thread.member]
- C++14 standard (ISO/IEC 14882:2014):
- 30.3.1.5 thread members [thread.thread.member]
- C++11 standard (ISO/IEC 14882:2011):
- 30.3.1.5 thread members [thread.thread.member]
[edit] See also
returns the id of the thread (public member function) | |
waits for the thread to finish its execution (public member function) | |
permits the thread to execute independently from the thread handle (public member function) |