#include <future>#include <iostream>#include <thread> int main(){// future from a packaged_taskstd::packaged_task<int()> task([]{return7;});// wrap the function    std::future<int> f1= task.get_future();// get a futurestd::thread t(std::move(task));// launch on a thread // future from an async()    std::future<int> f2=std::async(std::launch::async,[]{return8;}); // future from a promisestd::promise<int> p;    std::future<int> f3= p.get_future();std::thread([&p]{ p.set_value_at_thread_exit(9);}).detach(); std::cout<<"Waiting..."<<std::flush;    f1.wait();    f2.wait();    f3.wait();std::cout<<"Done!\nResults are: "<< f1.get()<<' '<< f2.get()<<' '<< f3.get()<<'\n';    t.join();}

Waiting...Done!Results are: 7 8 9

#include <future>#include <iostream>#include <thread> int main(){std::promise<int> p;    std::future<int> f= p.get_future(); std::thread t([&p]{try{// code that may throwthrowstd::runtime_error("Example");}catch(...){try{// store anything thrown in the promise                p.set_exception(std::current_exception());}catch(...){}// set_exception() may throw too}}); try{std::cout<< f.get();}catch(conststd::exception& e){std::cout<<"Exception from the thread: "<< e.what()<<'\n';}    t.join();}

Exception from the thread: Example