C++11 新标准中引入了四个头文件来支持多线程编程，他们分别是<atomic> ,<thread>,<mutex>,<condition_variable>和<future>。

• <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。

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

void f1(int n)
{
    for (int i = 0; i < 5; ++i) {
        std::cout << "Thread 1 executing\n";
        ++n;
        std::this_thread::sleep_for(std::chrono::milliseconds(10));
    }
}

void f2(int& n)
{
    for (int i = 0; i < 5; ++i) {
        std::cout << "Thread 2 executing\n";
        ++n;
        std::this_thread::sleep_for(std::chrono::milliseconds(10));
    }
}

class foo
{
public:
    void bar()
    {
        for (int i = 0; i < 5; ++i) {
            std::cout << "Thread 3 executing\n";
            ++n;
            std::this_thread::sleep_for(std::chrono::milliseconds(10));
        }
    }
    int n = 0;
};

class baz
{
public:
    void operator()()
    {
        for (int i = 0; i < 5; ++i) {
            std::cout << "Thread 4 executing\n";
            ++n;
            std::this_thread::sleep_for(std::chrono::milliseconds(10));
        }
    }
    int n = 0;
};

int main()
{
    int n = 0;
    foo f;
    baz b;
    std::thread t1; // t1 is not a thread
    std::thread t2(f1, n + 1); // pass by value
    std::thread t3(f2, std::ref(n)); // pass by reference
    std::thread t4(std::move(t3)); // t4 is now running f2(). t3 is no longer a thread
    std::thread t5(&foo::bar, &f); // t5 runs foo::bar() on object f
    std::thread t6(b); // t6 runs baz::operator() on object b
    t2.join();
    t4.join();
    t5.join();
    t6.join();
    std::cout << "Final value of n is " << n << '\n';
    std::cout << "Final value of foo::n is " << f.n << '\n';
}

获取线程ID和CPU核心数:

#include <iostream>       // std::cout
#include <thread>         // std::thread, std::this_thread::sleep_for
#include <chrono>         // std::chrono::seconds
using namespace std;
void func()
{
    this_thread::sleep_for (chrono::seconds(1));//休眠1秒
    //获取当前线程id
    cout << "func id = " << this_thread::get_id() << endl;
}

int main()
{
    thread t(func);
    cout << "t.get_id() = " << t.get_id() << endl; //获取线程t的id
    cout << "main id = "<<this_thread::get_id() << endl; //主线程id
    cout << "cup num = " << thread::hardware_concurrency() << endl;//获取cpu核心数，失败返回0
    t.join(); //线程阻塞
    return 0;
}