Syntax issue when populating an array with a fold expression

Question

Yes, I can use std::initializer_list. Yes, even easier, I can do aggregate initialization. But how does this work? I can\'t seem to fold my head around C++17\'s fol

Answer 1

Since the comma operator is left-associative, you would ideally use a left unary fold:

(...,void(arr[i++] = pack))

The cast to void is to make sure that the built-in comma operator is used. In this case, the handedness doesn't actually matter.

Answer 2

You need to fold with the comma operator, which also solves the sequencing problem.

(void(arr[i++] = pack) , ...);