CODEWITHSUNDEEP
c++binary-tree
user8836784
user8836784

Reputation:

I cannot print the value of the pointer

I am working on the small program below in order to understand binary trees a bit better. I simply wanted to make sure that the pointer *padre is being assigned correctly, however nothing prints to the console and I think it has to do with me not understanding how pointers work. Please help.

#include <stdio.h>
#include<iostream>
using namespace std;

class Nodo {
public:
    Nodo(int valor) {
        dato = valor;
        izquierdo = 0;
        derecho = 0;
    }
    int dato;
    Nodo* izquierdo;
    Nodo* derecho;
};

void Agregar(Nodo** padre, Nodo* hijo) {
    if ( !*padre ) {
        *padre = hijo;
        printf("valor: %i", &(*padre)->dato);
        return;
    }

}

int main() {
    Nodo* padre = new Nodo(5);
    Agregar(NULL, padre);
}

Upvotes: 0

Views: 112

Answers (1)

BeyelerStudios
BeyelerStudios

Reputation: 4283

You're invoking undefined behaviour by accessing a nullptr: you're passing NULL as the first argument to Agregar. Fixing up your code to get the expected printout of the node's value looks like this:

#include <cstdio>

class Nodo {
public:
    Nodo(int valor) {
        dato = valor;
        izquierdo = 0;
        derecho = 0;
    }
    int dato;
    Nodo* izquierdo;
    Nodo* derecho;
};

void Agregar(Nodo** padre, Nodo* hijo) {
    if ( !*padre ) {
        *padre = hijo;
        printf("valor: %i", (*padre)->dato); // pass dato by value not by address
        return;
    }
}

int main() {
    Nodo* padre = new Nodo(5);
    Nodo* temp = nullptr;
    Agregar(&temp, padre); // first argument must not be nullptr
}

Upvotes: 1

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