I get Error <<'A::b' uses undefined class 'B'>> in c++

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I have below Code

C++

class B;
class A
{
	B b;
};
class B
{
	A a;
};

But I get Error <<'A::b' uses undefined class 'B'>>

How I can to use template for solve it

Posted 23-Jun-15 13:10pm

kave2011

Updated 23-Jun-15 14:10pm

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barneyman 23-Jun-15 19:35pm

because it does!

google for 'circular dependency' and you'll find some solutions

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Sergey Alexandrovich Kryukov · Answer 1 · 2015-06-23T13:55:00

If it was possible, you could not initialize the instances of any of these classes, because it would recursively create infinite number of A and B instances. But you could have a pointers of these types as instance members. You should avoid the situation with infinite recursive instantiation, even with pointers. For example, if a and b were pointers, a.B and b.A could point to each other.

—SA