What are some examples of using std::any in C++17?

Can you explain what std::any is in C++17?

Sure! std::any is a type-safe container for single values of any type. It allows you to store values without knowing their type at compile time.

Can you give me an example of how to use std::any?

Absolutely! Here's a simple example:

#include <any>
#include <iostream>

int main() {
    std::any value = 42; // storing an int
    std::cout << std::any_cast<int>(value) << std::endl; // outputs 42
    value = std::string("Hello, World!"); // now storing a string
    std::cout << std::any_cast<std::string>(value) << std::endl; // outputs Hello, World!
}

What happens if I try to cast to the wrong type?

If you try to cast to the wrong type, std::any_cast will throw a std::bad_any_cast exception. It's important to ensure the type matches!

Are there any limitations to using std::any?

Yes, std::any can introduce some overhead due to type erasure and may not be as efficient as using specific types directly. It's best used when type flexibility is needed.