What are the differences between futures and promises in C++?

Can you explain the differences between futures and promises in C++?

Sure! In C++, a promise is a way to set a value that will be available in the future, while a future is a way to retrieve that value once it's set.

How do I create a promise and a future in my code?

You can create a promise using std::promise<T> and a future using std::future<T>. You link them by calling get_future() on the promise.

What happens if I try to get a value from a future that hasn't been set yet?

If you try to get a value from a future that hasn't been set, it will block until the value is available or throw an exception if the promise was set to an error.

Can I use futures and promises with threads?

Yes, futures and promises are often used with threads to synchronize the results of asynchronous operations.