Reading return values from threads

In this recipe, we'll continue from the previous recipe. Here, we'll fetch the answers as return values from the threads instead of letting them print the result themselves. This is like the return values from functions.

Knowing how to fetch the return values from threads enables you to do much more complicated things with threads.

Getting ready

In order for this recipe to make sense, it's advised that you complete the previous recipe first.

You'll also need the Makefile that we wrote in the previous recipe.

How to do it…

This program is similar to that of the previous recipe, but instead of each thread printing its own result, they return it to main(). This is similar to how functions return a value to main(), only here we need to do some casting back and forth. The downside of this approach is that we won't see the result until both threads are finished unless we intentionally give the first thread...