Binary tree pointer error

Question

I have three functions to managa a binary tree :

static void insertion(Noeud* &top, Noeud *newNoeud)
{
    if(top == NULL)
        top = newNoeud;
    else if(newNoeud->nbr < top->nbr)
        insertion(top->left, newNoeud);
    else
        insertion(top->right, newNoeud);
}

static void affichage(Noeud* &top) //displaying
{
    if(top != NULL)
    {
        affichage(top->left);
        affichage(top->right);
        cout << "\n" << top->nbr;
    }
}

static Noeud* recherche(Noeud* &top, int nbr) //searching 
{
    while(top != NULL)
    {
        if(top->nbr == nbr)
            return(top);
        else if(nbr < top->nbr)
            top = top->left;
        else
            top = top->right;
    }
}

however I keep getting an error saying that I am violating the access when trying to read a memory spot. I am guessing this has to do with my pointers but I can't guess what it is.

Have you tried running in a debugger? Where exactly does it crash? Have you tried valgrind, if you're on Linux? — rutgersmike
– rutgersmike, Commented Nov 25, 2012 at 4:34
Since static Noeud* recherche(Noeud* &top, int nbr) means what it means in C++, you're passing top by reference, top = top->left; resp. top = top->right; will destroy your tree. — Daniel Fischer
– Daniel Fischer, Commented Nov 25, 2012 at 4:47

Roee Gavirel · Accepted Answer · 2012-11-25 06:02:49Z

1

the recherche changes the top which it shouldn't.

Does this even compiled ?

static Noeud* recherche(Noeud* &top, int nbr) //searching 
{
    while(top != NULL)
    {
        if(top->nbr == nbr)
            return(top);
        else if(nbr < top->nbr)
            top = top->left;
        else
            top = top->right;
    }
}

This doesn't always return a value...

should be something like that:

static Noeud* recherche(Noeud* &top, int nbr) //searching 
{
    Noeud* it = top; //use a temporary pointer for the search.
    while(it != NULL)
    {
        if(it->nbr == nbr)
            return(it);
        else if(nbr < it->nbr)
            it = it->left;
        else
            it = it->right;
    }
    return it; //always return a value.
}

answered Nov 25, 2012 at 6:02

Roee Gavirel

19.6k13 gold badges69 silver badges98 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Yakk - Adam Nevraumont · Accepted Answer · 2012-11-25 05:58:33Z

1

Your search method makes your top node not point to top anymore.

edited Nov 25, 2012 at 5:58

Yakk - Adam Nevraumont

280k31 gold badges367 silver badges585 bronze badges

answered Nov 25, 2012 at 5:11

GiGImushroom

314 bronze badges

Collectives™ on Stack Overflow

Binary tree pointer error

2 Answers 2

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related