using objects in class

Question

Is it possible to use objects that are from other class abd use it in a different class?
If so how?
As the object is not declared when the class is being created.

Answer 1

Composition.

class A
{
public: void speak() { std::cout << "Hi"; }
};

class B
{
public: void doStuff() { obj.speak(); }
private: A obj;
};

int main()
{
B obj;
obj.doStuff();
return 0;
}