Is it possible to construct a class inside of a class?

Question

Is it possible to create a class within another class? Is treating my class declaration as a member function. Here is my code:

struct Handler{
  int *_value = nullptr;
  Handler(int& value)
  {
    _value = &value;
  }
};
struct action{
  int _value = 0;
  Handler handler(_value);
};

So I want the _value in the struct Handler have the same adress with the _value in struct action, so when I change one of them, the other one will have the same value.

Make it `Handler handler{_value};` (note braces). [Demo](https://rextester.com/DARLK26309) — Igor Tandetnik, Jul 19 '19 at 03:33
Thank you! now it is working because its not treated as a member function! — Eden Cheung, Jul 19 '19 at 03:34
Possible duplicate of [Nested Classes C++](https://stackoverflow.com/questions/5827637/nested-classes-c) — rsjaffe, Jul 19 '19 at 03:37

score 2 · Accepted Answer · answered Jul 19 '19 at 03:42

Default member initializers only support brace or equals initializer, but not parentheses initializer. So you can write it as

Handler handler{_value};           // list initialization (since C++11)

or

Handler handler = Handler(_value); // copy initialization

Is it possible to construct a class inside of a class?

1 Answers1