How do I handle errors in asynchronous C++ code?

How do I handle errors in asynchronous C++ code?

In C++, you can handle errors in asynchronous code using try-catch blocks, futures, and promises. Would you like an example?

Yes, please provide an example of using futures.

Sure! Here's a simple example:

#include <future>
#include <iostream>
#include <stdexcept>

int riskyFunction() {
    throw std::runtime_error("An error occurred!");
}

int main() {
    std::future<int> result = std::async(std::launch::async, riskyFunction);
    try {
        int value = result.get(); // This will throw an exception
    } catch (const std::exception& e) {
        std::cout << "Caught an error: " << e.what() << std::endl;
    }
}

This code demonstrates how to catch exceptions thrown by asynchronous tasks.

What if I want to handle multiple asynchronous tasks?

You can use std::when_all from the future library to wait for multiple futures. If any task fails, you can handle the exceptions accordingly.

Can you show me how to do that?

Certainly! Here's an example:

#include <future>
#include <iostream>
#include <vector>
#include <stdexcept>

int task(int id) {
    if (id % 2 == 0) throw std::runtime_error("Error in task " + std::to_string(id));
    return id;
}

int main() {
    std::vector<std::future<int>> futures;
    for (int i = 0; i < 5; ++i) {
        futures.push_back(std::async(std::launch::async, task, i));
    }
    for (auto& fut : futures) {
        try {
            std::cout << "Result: " << fut.get() << std::endl;
        } catch (const std::exception& e) {
            std::cout << "Caught an error: " << e.what() << std::endl;
        }
    }
}

This will handle errors from multiple tasks.