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std::thread::join

void join();

当该线程执行完成后才返回。（即等待子线程执行完毕才继续执行主线程）

该函数的返回与子线程执行完毕同步，该函数会阻塞调用该函数的线程直到子线程调用完毕。

例子：

#include <iostream>
#include <thread>
#include <vector>
#include <ctime>
using namespace std;
//delay(n) 延时n秒  
void delay(double sec)  
{  
    time_t start_time, cur_time; // 变量声明  
    time(&start_time);  
    do {  
        time(&cur_time);  
        }while((cur_time - start_time) < sec );  
};  
void show(int n){
	while(n>5){
		cout<<"currentThread is "<<pthread_self()<<",Now n is "<<n<<endl;
		delay(1);
		n--;
	}
}
int main()
{
	cout<<"main starts"<<endl;
	thread t2(show,10);
	//t2.join();
	cout<<"main complete!"<<endl;
}

可以看到,t2还没有执行完毕就已经结束了。

加上t2.join()之后的执行结果：

可以看到，阻塞了主线程，等待t2执行完毕才继续执行main线程。

调用该函数后，子线程对象变成non-joinable以及可以安全地销毁。

Parameters

Return value

Example

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// example for thread::join
#include <iostream>       // std::cout
#include <thread>         // std::thread, std::this_thread::sleep_for
#include <chrono>         // std::chrono::seconds
 
void pause_thread(int n) 
{
  std::this_thread::sleep_for (std::chrono::seconds(n));
  std::cout << "pause of " << n << " seconds ended\n";
}
 
int main() 
{
  std::cout << "Spawning 3 threads...\n";
  std::thread t1 (pause_thread,1);
  std::thread t2 (pause_thread,2);
  std::thread t3 (pause_thread,3);
  std::cout << "Done spawning threads. Now waiting for them to join:\n";
  t1.join();
  t2.join();
  t3.join();
  std::cout << "All threads joined!\n";

  return 0;
}

Spawning 3 threads...
Done spawning threads. Now waiting for them to join:
pause of 1 seconds ended
pause of 2 seconds ended
pause of 3 seconds ended
All threads joined!

Data races

Exception safety

Note that if the thread represented by the object terminates with an uncaught exception, this cannot be caught by the current thread, and terminate() is automatically called.

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转载请注明出处：http://blog.csdn.net/qq844352155

author:天下无双

Email:coderguang@gmail.com

2014-9-4

于GDUT

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C++11 thread::join(4)

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原文地址：http://blog.csdn.net/qq844352155/article/details/39049475