c++之多线程创建的三种方式

c++11之后支持了多线程编程。在 C++11 中我们可以通过创建 std::thread 对象来创建新的线程。每个 std::thread 对象都可以与一个线程相关联。

给 std::thread 对象添加函数，std::thread thObj();这个回调函数将在这个新线程启动时执行。这些回调可以是：

1. 函数指针
2. 函数对象
3. Lambda函数

使用函数指针创建线程

#include <iostream>
#include <thread>
using namespace std;
void thread_function()
{
	for (int i = 0; i < 10; i++)
	{
		cout << "Thread function executing!" << endl;
	}
}
int main()
{
	std::thread threadObj(thread_function);

	for (int i = 0; i < 10; i++)
	{
		cout << "MainThread executing!" << endl;
	}
	threadObj.join();//等到子线程结束，主线程再结束

	cout << "EXIT!!" << endl;

	system("pause");
	return 0;

使用函数对象创建线程

#include <iostream>
#include <thread>
using namespace std;

class DisplayThread
{
public:
	void operator()()
	{
		for (int i = 0; i < 10; i++)
		{
			cout << "Thread function executing!" << endl;
		}
	}
};
int main()
{
	thread threadObj((DisplayThread()));
	
	for (int i = 0; i < 10; i++)
	{
		cout << "MainThread executing!" << endl;
	}
	threadObj.join();//等到子线程结束，主线程再结束
	cout << "EXIT!!" << endl;

	system("pause");
	return 0;
}

使用 Lambda 函数创建线程

#include <iostream>
#include <thread>
using namespace std;

int main()
{
	thread threadObj([] {
		for (int i = 0; i < 10; i++)
		{
			cout << "Thread function executing!" << endl;
		}});
	
	for (int i = 0; i < 10; i++)
	{
		cout << "MainThread executing!" << endl;
	}
	threadObj.join();//等到子线程结束，主线程再结束
	cout << "EXIT!!" << endl;

	system("pause");
	return 0;
}

如何区分线程

每个 std::thread 对象都有一个 ID，使用下面的函数可以获取：

std::thread::get_id()

获取当前线程的 ID：

std::this_thread::get_id()

#include <iostream>
#include <thread>
using namespace std;

void thread_function()
{
	cout << "Inside Thread :: ID = " << this_thread::get_id() << endl;
}
int main()
{
	thread threadObj1(thread_function);
	thread threadObj2(thread_function);
	if (threadObj1.get_id() != threadObj2.get_id())
	{
		cout << "Both Threads have different IDs!" << endl;
	}
	cout << "From main Thread :: ID of threadObj1 is " << threadObj1.get_id() << endl;
	cout << "From main Thread :: ID of threadObj2 is " << threadObj2.get_id() << endl;
	threadObj1.join();
	threadObj2.join();//等到子线程结束，主线程再结束
	cout << "EXIT!!" << endl;

	system("pause");
	return 0;
}

————————————————
转载自：https://blog.youkuaiyun.com/weixin_42579072/article/details/103021724