C++11 thread::joinable(5)

原文地址：http://www.cplusplus.com/reference/thread/thread/joinable/

public member function

<thread>

std::thread::joinable

bool joinable() const noexcept;

Check if joinable

Returns whether the thread object is joinable.

返回线程对象是否是joinable的。

A thread object is joinable if it represents a thread of execution.

如果是一个正在执行的线程，那么它是joinable的。

A thread object is not joinable in any of these cases:

下列任一情况都是非joinable

• if it was default-constructed.
  默认构造器构造的。
• if it has been moved from (either constructing another thread object, or assigning to it).
  通过移动构造获得的。
• if either of its members join or detach has been called.
  调用了join或者detach方法的。
  
  
  

例子：

#include <iostream>#include <thread>#include <ctime>using namespace std;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){cout<<"n="<<n<<endl;}thread returnThread(){thread tt(show,10);return tt;}int main(){thread t(show,18);cout<<"t is joinable? "<<t.joinable()<<endl;thread t1(returnThread());cout<<"t1 is joinable? "<<t1.joinable()<<endl;thread t2(show,3);cout<<"t2 is joinable? "<<t2.joinable()<<endl;t2.join();cout<<"after t2.join(),t2 is joinable? "<<t2.joinable()<<endl;thread t3(show,5);cout<<"t3 is joinable? "<<t3.joinable()<<endl;t3.detach();cout<<"after t3.detach(),t3 is joinable? "<<t3.joinable()<<endl;}

运行结果：

用GDB调试发现一个好神奇的东西。

运行完了

cout<<"after t3.detach(),t3 is joinable? "<<t3.joinable()<<endl;

之后，居然像栈析解一样，好神奇阿，现在还不知道为什么呢。。

先保留着，下次解决。

Parameters

none

Return value

true if the thread is joinable.
false otherwise.

Example

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// example for thread::joinable#include <iostream>       // std::cout#include <thread>         // std::thread void mythread() {  // do stuff...} int main() {  std::thread foo;  std::thread bar(mythread);  std::cout << "Joinable after construction:\n" << std::boolalpha;  std::cout << "foo: " << foo.joinable() << '\n';  std::cout << "bar: " << bar.joinable() << '\n';  if (foo.joinable()) foo.join();  if (bar.joinable()) bar.join();  std::cout << "Joinable after joining:\n" << std::boolalpha;  std::cout << "foo: " << foo.joinable() << '\n';  std::cout << "bar: " << bar.joinable() << '\n';  return 0;}

Edit & Run

Output (after 3 seconds):

Joinable after construction:foo: falsebar: trueJoinable after joining:foo: falsebar: false

Data races

The object is accessed.

Exception safety

No-throw guarantee: never throws exceptions.

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

author:天下无双

Email:[e-mail]

2014-9-4

于GDUT

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