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Carlos Peralta
Asked: 2022-10-22 09:05:10 +0800 CST 2022-10-22 09:05:10 +0800 CST

Pile with Templates

  • 772

I have an error in the node class, when I try to do this with templates

the error that tells me: template arguments required for class Stack

Node class:

#ifndef NODO_H_INCLUDED
#define NODO_H_INCLUDED
#include <stdlib.h>
template <class T>
class Nodo{
private:
    T Valor;
    Nodo<T> *siguiente;
public:
    Nodo(T v){
        this->Valor=v;
        this->siguiente=NULL;
    }
    void setSiguiente(Nodo<T> *sig){
        this->siguiente=sig;
    }
friend class Pila;
};

#endif // NODO_H_INCLUDED

Stack Class:

#ifndef PILA_H_INCLUDED
#define PILA_H_INCLUDED
#include "Nodo.h"
template <class T>
class Pila{
    private:
        Nodo<T> *Primero;
        Nodo<T> *Ultimo;
        bool PilaVacia(){
            return (this->Primero==NULL);
        }
    public:
        Pila(){
            this->Primero=NULL;
            this->Ultimo=NULL;
        }

        void Meter(T n){
            Nodo<T> *nuevo=new Nodo<T>(n);
            if(this->PilaVacia()){
                this->Primero=nuevo;
            }
            else{
                this->Ultimo->setSiguiente(nuevo);
            }
            this->Ultimo=nuevo;
        }
};


#endif // PILA_H_INCLUDED

main.cpp

#include <iostream>
#include "Pila.h"
using namespace std;

int main()
{
    Pila<int> pl;
    pl.Meter(1);
    cout << "Hello world!" << endl;
    return 0;
}

[The error sends me to the following line1

At the moment it is the scheme that I must do, I don't know why it sends me to that error, I can't find a solution, I also don't know why it doesn't recognize the Stack class as a friend, if it already has the friend class Stack

c++

1 Answers

  1. Best Answer

    Notice that in the file Nodoyou are declaring the Stack class by:

    friend class Pila;

    This brings you conflicts with the definition of Pilasince one is a template and the other is not. You should simply use the class name:

    friend Pila;

    But since Pilait's a template you can't make all of Pilathe specs class-friendly. Just one at a time which is all you need:

    friend Pila<T>;

    Also in the class Nodothere is none #includeof the class Pila. So to avoid cyclic inclusion problems better remove that line and write this one in the class file Pila:

    friend Nodo<T>;

    You would have something like this:

    node.h

    template <class T>
class Nodo{
    ...
}

    Stack.h

    #include "Pila.h"
template <class T>
class Pila {
    ...
    friend Nodo<T>;
}

    By the way, for now you don't need the classes to be friends since you're not accessing any private variables or functions of the other.

    The code would look like this:

    node.h

    template <class T>
class Nodo{
private:
    T Valor;
    Nodo<T> *siguiente;
public:
    Nodo(T v){
        this->Valor=v;
        this->siguiente=NULL;
    }
    void setSiguiente(Nodo<T> *sig){
        this->siguiente=sig;
    }
};

    Stack.h

    #include "Nodo.h"
template <class T>
class Pila{
    private:
        Nodo<T> *Primero;
        Nodo<T> *Ultimo;
        bool PilaVacia(){
            return (this->Primero==NULL);
        }
    public:
        Pila(){
            this->Primero=NULL;
            this->Ultimo=NULL;
        }

        void Meter(T n){
            Nodo<T> *nuevo=new Nodo<T>(n);
            if(this->PilaVacia()){
                this->Primero=nuevo;
            }
            else{
                this->Ultimo->setSiguiente(nuevo);
            }
            this->Ultimo=nuevo;
        }

    friend Nodo<T>;
};

    You can see other errors that may be clearer in another compiler and try it here .

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