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 thethreadobject isjoinable.

返回线程对象是否是joinable的。

Athreadobject isjoinableif it represents a thread of execution.

如果是一个正在执行的线程，那么它是joinable的。

Athreadobject isnot joinablein any of these cases:

下列任一情况都是非joinable

• if it wasdefault-constructed.
  默认构造器构造的。
• if it has been moved from (eitherconstructinganotherthreadobject, orassigning to it).
  通过移动构造获得的。
• if either of its membersjoinordetachhas 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

trueif the thread isjoinable.
falseotherwise.

Example

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27

// 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: false
bar: true
Joinable after joining:
foo: false
bar: 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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