C++学习之线程详解

// 函数方式
void fun(string s){
    cout<< &s<<endl;
    cout<< "first thread programm"<<s<<endl;
}

int main(){
	string s = "Hell world";
	thread th = thread(fun, s);
	th.join();
}

long n =0;
clock_t start,finish;
start=clock();
while(n<1000000000)
	n++;
finish=clock();
printf("spend time %f s \n", (double)(finish-start)/CLOCKS_PER_SEC);
printf("spend time %f ms \n", (double)(finish-start)/1000);

#include <chrono>

//方式三 chrono
std::chrono::system_clock::time_point Cstart = std::chrono::system_clock::now();    //系统时间
//    std::chrono::steady_clock::time_point Cstart = std::chrono::steady_clock::now();    //稳定时间

long n =0 ;
while(n<1000000000)n++;
std::chrono::system_clock::time_point Cend = std::chrono::system_clock::now();    //系统时间

std::chrono::duration<float> spend_time = Cend-Cstart;
cout<<spend_time.count()<<endl;

mutex mtx;   //创建互斥锁对象

mtx.lock();
g_pcm_elapseds.push_back(std::make_pair(pcm_data, elapsed));	// 执行语句
mtx.unlock();

std::mutex mtx;
std::condition_variable cv;
bool ready = false;


void print_thread_id(int id){
    std::unique_lock<std::mutex> lck(mtx);
    cv.wait(lck,[]{return ready;});
    std::cout<< "thread"<<id <<endl;
}

void go(){
    std::unique_lock<std::mutex> lck(mtx);
    ready = true;
    cv.notify_all();    // 唤醒所有线程
};


int main(){
    std::thread threads[10];
    for(int i=0;i<10;i++){
        threads[i] = std::thread(print_thread_id,i);
    }
    std::cout<< " thread read all done"<<endl;
    go();
    for(auto &th:threads) th.join();
    return 0;
}