multy inheritence

[terracota]

hi

I cant find a way to initialize or call the constructors of 2 base classes from a another one using inheritance

#include <iostream>
using std::cout;
using std::endl;

//Base class
class Base{
	public:
	      virtual void print() = 0;
};

//derived 1
class DerivadaUno:virtual public Base{
	public:
	    DerivadaUno(int n1){numeroUno = n1;}
	   void imprimir(){cout << "DerivadaUno\n"
                                                   << numeroUno;}
	private:
	   int numeroUno;
};

//derived 2
class DerivadaDos:virtual public Base{
	public:
	   DerivadaDos(int n2){numeroDos = n2;}
	   void imprimir(){cout << "DerivadaDos\n" << 
                                                   << numeroDos;}
	private:
	   int numeroDos;
};

//class multy derived from derived 1 and 2
class Multiple:public DerivadaUno, public DerivadaDos{
	public:
	    //cant initialize DerivadaUno and DerivaDaDos
                    //why and how?
                    Multiple(int nu1, int nu2)
		:DerivadaUno(nu1), DerivadaDos(nu2){}
		
	   void imprimir(){DerivadaDos::imprimir();}
};

int main()
{
	Multiple ambas(25,40);
	DerivadaUno uno;
	DerivadaDos dos;

	Base *arreglo[3];
	arreglo[0] = &ambas; 
	arreglo[1] = &uno; 
	arreglo[2] = &dos; 
	
	for(int i = 0; i < 3; i++)
		arreglo[i]->imprimir();

	cout << endl;
	return 0;
}

ok if you see i'm trying to call the explicit constructors but the compiler generates 3 error messages:

thanks for any help and please excuse my poor english
----------------------------------------------------------------------------------
main.cpp

C:\programas c++\ejer22_14\main.cpp(47) : error C2664: '__thiscall Multiple::Multiple(const class Multiple &)' : cannot convert parameter 1 from 'const int' to 'const class Multiple &'
Reason: cannot convert from 'const int' to 'const class Multiple'
No constructor could take the source type, or constructor overload resolution was ambiguous
C:\programas c++\ejer22_14\main.cpp(48) : error C2512: 'DerivadaUno' : no appropriate default constructor available
C:\programas c++\ejer22_14\main.cpp(49) : error C2512: 'DerivadaDos' : no appropriate default constructor available
Error executing cl.exe.

ejer22_14.exe - 3 error(s), 0 warning(s)
----------------------------------------------------------------------------------

[misplaced]

i think you must define print in all children of the Base class because it is a pure virtual class...

does imprimir mean 'to print'?...if so, change it to 'print' or remove the = 0 in print() = 0 and define it to {cout << "Base class"; } or something....


on a side note,
constructor errors are tricky...whenever you get them tyr not to focus too much on the constructors themselves and think outside the box

[jlou]

You are calling the constructors for the base classes correctly.

misplaced is right, your print function is called print in the base class and imprimir in the derived classes. Change it to imprimir in the base class.

Also, you have an extra "<<" in DerivadaDos's imprimir function. Remove it.

And finally, in main, you try to instantiate a new DerivadaUno and DerivadaDos but the only constructors for those require an integer. Either provide an integer for those objects, or add a new constructor for those two classes that doesn't require an integer. For any class, once you write a constructor that takes one or more arguments, you can no longer use the default constructor that takes no arguments.

[terracota]

thanks for reply misplaced and jlou

and please sorry for posting my own post

i must overload both constructors in derivedUno and derivedDos
ok?

//derived1
DerivadaUno(int n1):numeroUno(n1){}
DerivadaUno():numeroUno(0){}

//derived2
DerivadaDos(int n2):numeroDos(n2){}
DerivadaDos():numeroDos(0){}

and yes imprimir = print

sorry obut the print problem was my mistake not copying te code just retyping

know the code works great

[jlou]

Another way to do it:

//derived1
DerivadaUno(int n1 = 0):numeroUno(n1){}

//derived2
DerivadaDos(int n2 = 0):numeroDos(n2){}

[terracota]

thanks al lot
looks better