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std::thread::join(3)	       C++ Standard Libary	    std::thread::join(3)

NAME
     std::thread::join - std::thread::join

Synopsis
	void join();  (since C++11)

	Blocks	the current thread until the thread identified by *this finishes
     its
	execution.

	The completion of the thread identified by *this synchronizes  with  the
     corresponding
	successful return from join().

	No  synchronization  is  performed on *this itself. Concurrently calling
     join() on the
	same thread object from multiple threads constitutes a	data  race  that
     results in
	undefined behavior.

Parameters
	(none)

Return value
	(none)

Postconditions
	joinable() is false.

Exceptions
	std::system_error if an error occurs.

	Error conditions

	  *	 resource_deadlock_would_occur	    if	   this->get_id()     ==
     std::this_thread::get_id()
	    (deadlock detected).
	  * no_such_process if the thread is not valid.
	  * invalid_argument if joinable() is false.

Example
     // Run this code

      #include <chrono>
      #include <iostream>
      #include <thread>

      void foo()
      {
	  // simulate expensive operation
	  std::this_thread::sleep_for(std::chrono::seconds(1));
      }

      void bar()
      {
	  // simulate expensive operation
	  std::this_thread::sleep_for(std::chrono::seconds(1));
      }

      int main()
      {
	  std::cout << "starting first helper...\n";
	  std::thread helper1(foo);

	  std::cout << "starting second helper...\n";
	  std::thread helper2(bar);

	  std::cout << "waiting for helpers to finish..." << std::endl;
	  helper1.join();
	  helper2.join();

	  std::cout << "done!\n";
      }

Output:
      starting first helper...
      starting second helper...
      waiting for helpers to finish...
      done!

References
	  * C++23 standard (ISO/IEC 14882:2023):

	  * 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]

See also
	detach	 permits the thread to execute	independently  from  the  thread
     handle
		 (public member function)
		 checks whether the thread is joinable, i.e. potentially running
     in parallel
	joinable context
		 (public member function)
	C documentation for
	thrd_join

http://cppreference.com 	   2024.06.10		    std::thread::join(3)
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