What is std::variant in C++17 and how do I use it?

What is std::variant in C++17 and how do I use it?

std::variant is a type-safe union that can hold one of several types. You can use it to store different types in a single variable.

Can you give me an example of how to declare and use std::variant?

Sure! You can declare a variant like this: std::variant<int, std::string> myVar;. You can then assign an int or a string to it.

How do I access the value stored in a std::variant?

You can use std::get<T>(myVar) to access the value, where T is the type you expect. If the type doesn't match, it will throw an exception.

What happens if I try to access a type that isn't currently held by the variant?

If you try to access a type that isn't currently held, std::get will throw a std::bad_variant_access exception.