What are the advanced features of std::variant in C++17?

What are the advanced features of std::variant in C++17?

C++17's std::variant allows for type-safe unions. It supports features like visitation, type indexing, and more.

Can you explain how visitation works with std::variant?

Visitation is done using std::visit, which applies a visitor function to the active member of the variant.

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

If you try to access a type not held by the variant, it will throw std::bad_variant_access.

Are there any performance considerations I should be aware of?

Yes, std::variant can have overhead due to type erasure and may increase code size, so use it judiciously.