stdthread创建

Posted 2022-03-29 thefist11

1.1 函数对象

class hello
public:
	void operator()()
		std::cout<<"Hello Concurrent World!"<<std::endl;
	
;

std::thread t(hello());//error，编译器会误以为是hello函数

std::thread t((hello())); //ok
std::thread thello(); //ok

1.2 例子

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 test()  
          
            int n = 0;  
            thread t1;               //t1是一个空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;  
           

输出：

Thread 1 executing
n=0
Thread 10 executing
n=30

1.3 lambda

void test() 
  
    auto fun = [](const char *str) cout << str << endl; ;  
    thread t1(fun, "hello world!");  
    thread t2(fun, "hello beijing!");   
    t1.join();
    t2.join();

输出：

hello world!
hello beijing!

1.4 可变参数

#include

int show(const char *fun, ...)  
  
    va_list ap;//指针  
    va_start(ap, fun);//开始  
    vprintf(fun, ap);//调用  
    va_end(ap);  
    return 0;  
  

int test()  
  
    thread t1(show, "%s    %d    %c    %f", "hello world!", 100, 'A', 3.14159); 
    t1.join(); 
    return 0;  
  

输出：

hello world!    100    A    3.141590