c++多线程学习，包含头文件、异步、睡眠、线程交换、线程移动和线程传参。
1. 线程头文件
C++11 新标准中引入了五个头文件来支持多线程编程
<atomic>：该头文主要声明了两个类, std::atomic 和 std::atomic_flag，另外还声明了一套 C 风格的原子类型和与 C 兼容的原子操作的函数。
<thread>：该头文件主要声明了 std::thread 类，另外 std::this_thread 命名空间也在该头文件中。
<mutex>：该头文件主要声明了与互斥量(mutex)相关的类，包括 std::mutex 系列类，std::lock_guard, std::unique_lock, 以及其他的类型和函数。
<condition_variable>：该头文件主要声明了与条件变量相关的类，包括 std::condition_variable 和 std::condition_variable_any。
<future>：该头文件主要声明了 std::promise, std::package_task 两个 Provider 类，以及 std::future 和 std::shared_future 两个 Future 类，另外还有一些与之相关的类型和函数，std::async() 函数就声明在此头文件中。
2. 线程异步
#include<thread>
using namespace std;
void show()
{
cout << "hello cplusplus!" << endl;
}
int main()
{
//栈上
thread t1(show); //根据函数初始化执行
thread t2(show);
thread t3(show);
//线程数组
thread th[3]{thread(show), thread(show), thread(show)};
//堆上
thread *pt1(new thread(show));
thread *pt2(new thread(show));
thread *pt3(new thread(show));
//线程指针数组
thread *pth(new thread[3]{thread(show), thread(show), thread(show)});
return 0;
}
3. 线程睡眠
#include<thread>
#include<chrono>
using namespace std;
int main()
{
thread th1([]()
{
//让线程等待3秒
this_thread::sleep_for(chrono::seconds(3));
//让cpu执行其他空闲的线程
this_thread::yield();
//线程id
cout << this_thread::get_id() << endl;
});
return 0;
}
4. 线程交换
#include<thread>
using namespace std;
int main()
{
thread t1([]()
{
cout << "thread1" << endl;
});
thread t2([]()
{
cout << "thread2" << endl;
});
cout << "thread1' id is " << t1.get_id() << endl;
cout << "thread2' id is " << t2.get_id() << endl;
cout << "swap after:" << endl;
swap(t1, t2);//线程交换
cout << "thread1' id is " << t1.get_id() << endl;
cout << "thread2' id is " << t2.get_id() << endl;
return 0;
}
运行结果:
thread1
thread2
thread1' id is 4836
thread2' id is 4724
swap after:
thread1' id is 4724
thread2' id is 4836
5. 线程移动
#include<thread>
using namespace std;
int main()
{
thread t1([]()
{
cout << "thread1" << endl;
});
cout << "thread1' id is " << t1.get_id() << endl;
thread t2 = move(t1);;
cout << "thread2' id is " << t2.get_id() << endl;
return 0;
}
运行结果:
thread1
thread1' id is 5620
thread2' id is 5620
6. 线程传参
#include<thread>
#include<chrono>
using namespace std;
void fun1(int n) //初始化构造函数
{
cout << "Thread " << n << " executing\n";
n += 10;
this_thread::sleep_for(chrono::milliseconds(10));
}
void fun2(int & n) //拷贝构造函数
{
cout << "Thread " << n << " executing\n";
n += 20;
this_thread::sleep_for(chrono::milliseconds(10));
}
int main()
{
int n = 0;
thread t1; //t1不是一个thread
thread t2(fun1, n + 1); //按照值传递
t2.join();
cout << "n=" << n << '\n';
n = 10;
thread t3(fun2, ref(n)); //引用
thread t4(move(t3)); //t4执行t3，t3不是thread
t4.join();
cout << "n=" << n << '\n';
return 0;
}
运行结果:
Thread 1 executing
n=0
Thread 10 executing
n=30