Insert node into binary tree

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How to insert a node into a binary tree? It always gives segmentation error when the code enters if (arv == NULL)

struct no {
  int info;
  struct no *esq;
  struct no *dir;
};


 typedef struct no node;


 struct  node *insere (node *arv, int valor) {

if (arv == NULL) {   //aqui esta o erro

   node p = malloc(sizeof(node));
   p.info = valor;
   p.esq = NULL;
   p.dir = NULL;
   *arv = p;

    return arv;
}
else if (valor > arv->info) {
    arv->dir = insere(arv->dir, valor);
    return arv->dir;
}
else {
        arv->esq = insere(arv->esq, valor);
return arv->esq;
}

 void imprime (node *arv) { 

if (arv != NULL) {

    imprime(arv->esq);
    printf("\n %d", arv->info);
    imprime(arv->dir);
}

}

int main (void) {

  node *arv;
  arv->info = 1;
  arv->dir = NULL;
  arv->esq = NULL;

  insere(arv, 2);
  insere(arv, 3);

  imprime(arv);
}
c algorithm pointer memory

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1 answer

1


This code doesn’t even compile, is very disorganized and has some flaws. I decided to allocate initial memory to the tree, which caused the described error, and then there were some more confusions in the allocation of nodes. There are still errors in the algorithm, but a step has been taken.

#include <stdio.h>
#include <stdlib.h>

typedef struct no {
    int info;
    struct no *esq;
    struct no *dir;
} Node;

Node *insere(Node *arv, int valor) {
    if (arv == NULL) {
        arv = malloc(sizeof(Node));
        arv->info = valor;
        arv->esq = NULL;
        arv->dir = NULL;
        return arv;
    } else if (valor > arv->info) {
        arv->dir = insere(arv->dir, valor);
        return arv->dir;
    } else {
        arv->esq = insere(arv->esq, valor);
        return arv->esq;
    }
}

void imprime (Node *arv) { 
    if (arv != NULL) {
        imprime(arv->esq);
        printf("\n %d", arv->info);
        imprime(arv->dir);
    }
}

int main (void) {
    Node *arv = malloc(sizeof(Node));
    arv->info = 1;
    arv->dir = NULL;
    arv->esq = NULL;
    insere(arv, 2);
    insere(arv, 3);
    imprime(arv);
}

Behold working in the ideone. And in the repl it.. Also put on the Github for future reference.

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