an error "variable of field declared void"

there's no variable quiz2 in your example. Please have a look at the lines numbers indicated by compiler.

Since neither A nor quiz2 appear in the code you've shown, I have to assume, you didn't actually show us the part of the code that causes the error.

It's not the code that you've posted. You'll need to show more of the header including line numbers, and give us the line number from the compiler errors.

1 Answer 1

I forgot that I must declare firstly classes and only after that functions, so now it's working

But @John, this isn't just an update to the question. It's the answer to the question. His failure to declare things in the right order is what caused the compiler errors. The solution to the errors was to change the declaration order. This answer could be phrased better, but it's still an answer. +1.