How can I use futures for thread synchronization in C++?

How can I use futures for thread synchronization in C++?

You can use std::future and std::promise in C++ to synchronize threads. A promise is used to set a value that a future can retrieve.

Can you give me a code example of using futures?

Sure! Here's a simple example:

#include <iostream>
#include <future>
#include <thread>

int calculateSquare(int x) {
    return x * x;
}

int main() {
    std::promise<int> promise;
    std::future<int> future = promise.get_future();
    std::thread t([&promise]() {
        promise.set_value(calculateSquare(5));
    });
    t.join();
    std::cout << "Square: " << future.get() << std::endl;
    return 0;
}

What happens if the promise is not set?

If the promise is not set before the future is accessed, calling future.get() will throw a std::future_error exception.

Are there any performance considerations when using futures?

Yes, using futures can introduce overhead due to thread management and context switching. It's important to evaluate if the benefits outweigh the costs in your specific use case.