The following code example is taken from the book
The C++ Standard Library - A Tutorial and Reference, 2nd Edition
by Nicolai M. Josuttis, Addison Wesley Longman, 2012
Copyright © 2012 by Pearson Education, Inc. and Nicolai M. Josuttis
#include <future>
#include <thread>
#include <chrono>
#include <random>
#include <iostream>
#include <exception>
using namespace std;
int doSomething (char c)
{
// random-number generator (use c as seed to get different sequences)
std::default_random_engine dre(c);
std::uniform_int_distribution<int> id(10,1000);
// loop to print character after a random period of time
for (int i=0; i<10; ++i) {
this_thread::sleep_for(chrono::milliseconds(id(dre)));
cout.put(c).flush();
}
return c;
}
int func1 ()
{
return doSomething('.');
}
int func2 ()
{
return doSomething('+');
}
int main()
{
std::cout << "starting func1() in background"
<< " and func2() in foreground:" << std::endl;
// start func1() asynchronously (now or later or never):
std::future<int> result1(std::async(func1));
int result2 = func2(); // call func2() synchronously (here and now)
// print result (wait for func1() to finish and add its result to result2
int result = result1.get() + result2;
std::cout << "\nresult of func1()+func2(): " << result
<< std::endl;
}