order of class declarations

[vitalishe]

I was trying to make an example where the declarations of two classes are interlinked and I came up with the following example.
Please, let me know what is a proper way of making the code work.

#include <iostream>

using namespace std;

// Class Chicken:
class Chicken{
public:
   Chicken();
   Egg * makeEgg();
};

// Class Egg:
class Egg{
public:
   Egg();
   ~Egg();
   Chicken * makeChicken();
};

public Egg * Chicken::makeEgg(){
   return new Egg();
};

public Chicken * Egg::makeChicken(){
   this->~Egg();
   return new Chicken;
}


int main(){
   cout << "What was first, the chicken or the egg?" << endl;
   cout << "Enter 1 for the chicken and 2 for the egg:" << endl;

   int creationChoice;
   cin >> creationChoice;

   Chicken * littleChicken;
   Egg * roundEgg;

   if (creationChoice==1){
      littleChicken = new Chicken();
      roundEgg = littleChicken->makeEgg();
   }else{
      roundEgg = new Egg();
      littleChicken = roundEgg->makeChicken();
   }

   cout << "Congratulations! The evolutionary question has been resolved.\n";

   return 0;
}

In its current form I am getting the following errors:

line 8: error: 'Egg' does not name a type
I assume this is because the class Egg was not yet defined.

line 18: error: expected unqualified-id before 'public'
line 22: error: expected unqualified-id before 'public'
These two are a mystery to me.

line 41: error: 'class Chicken' has no member named 'makeEgg'
It seams that I should only pay attention to the first error, as all later errors can be its consequence.

[Peter87]

line 8: error: 'Egg' does not name a type
I assume this is because the class Egg was not yet defined.

That's it. All you have in the Chicken class definition is a pointer to Egg so you don't need the full class definition of Egg. A forward declaration is enough.
class Egg;

line 18: error: expected unqualified-id before 'public'
line 22: error: expected unqualified-id before 'public'
These two are a mystery to me.

You should not put public at the beginning of the line when defining the member functions outside the class definition.

[vitalishe]

Thank you Peter. This resolved the main issues.
I had couple more small things (like missing definitions of constructors and destructors), but it works now.
Thanks a lot!

[NyhkoG1T]

From what I can see, the "missing definitions of constructors and destructors" is because you prototype the construct of both chicken and egg inside the class, "chicken(); and egg();" respectively, but then you don't define what to initialize. Also, you prototype the Egg destructor with "~Egg();" without following up with a defined destructor. You can either define them, or remove the prototypes, either way you can still directly refer to them because if you dont prototype or define a constructor/destructor, then it is done for you.

So, if you remove "Egg();" and "~Egg();" from the prototype inside Egg class, you will STILL be able to do this

public Chicken * Egg::makeChicken(){
   this->~Egg();
   return new Chicken;
}