How to implement union

Question

Hello

We all know that union allow us to have different data type and at a time only one memory address is allocated. I tried to replicate the same and thought to declare template class with template type data member as public member. But while instantiating object , we need to provide datatype for template which is not like union.

So , can anyone would plz give me some hint of how to implement union by our own ?

Answer 1

What you're ( probably ) talking about is an std::variant. It uses a variadic template to allow you to define the types.

I've never tried to implement one myself so all I can say is check out the gcc source code for it to get the general idea:
https://github.com/gcc-mirror/gcc/blob/master/libstdc%2B%2B-v3/include/std/variant

And good luck.