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// future::wait_for
#include <iostream> // std::cout
#include <future> // std::async, std::future
#include <chrono> // std::chrono::milliseconds
// a non-optimized way of checking for prime numbers:
bool is_prime (int x) {
for (int i=2; i<x; ++i) if (x%i==0) return false;
return true;
}
int main ()
{
// call function asynchronously:
std::future<bool> fut = std::async (is_prime,700020007);
// do something while waiting for function to set future:
std::cout << "checking, please wait";
std::chrono::milliseconds span (100);
while (fut.wait_for(span)==std::future_status::timeout)
std::cout << '.';
bool x = fut.get();
std::cout << "\n700020007 " << (x?"is":"is not") << " prime.\n";
return 0;
}
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