Binary Search Tree (C), segmentation fault in Insertion function

Question

Im trying to create an insertion function on an binary search tree. I looked at other questions here but they re not like my problem.

I can compile it but it crashes on the commented line below:

void insertNode(TreeNode** r, int n) {

TreeNode* novono;

    novono = createNode(n);
    if (*r == NULL){ //corrected
        *r = novono;
        (*r) -> right = NULL;
        (*r) -> left = NULL;
        (*r) -> data = n;
    }
    if (n < ((*r) -> data))
        insertNode(&((*r) -> left), n); //SEGMENTATION FAULT HERE
    if (n > ((*r) -> data))
        insertNode(&((*r) -> right), n); //SEGMENTATION FAULT HERE

}

This is the main function that tries to insert ints from a vector:

int main() {

#define MAX 15

TreeNode*   root    = NULL;
bool        OK      = true;
int         i       = 0, 
            n,
            V[MAX] = { 50, 10, 70, 2, 1, 13, 15, 65, 69, 77, 11, 3, 80, 76,   64}; 

    initTree(&root);
printf("Passou da inicialização");
    for ( i = 0 ; i < MAX ; i++ ) {
        printf("[%d] ", V[i]);

        insertNode(&root, V[i]);
        }

And this is the inicialization function that is executed before the insertion. (i dont think it is the problem, but im putting it here just cause i know you will ask for it).

void clearTree( TreeNode** r) {

    if ( *r != NULL) {
        printf("Clear %d\n", (*r)->data);
        clearTree(&(*r)->left);
        clearTree(&(*r)->right);
        free(*r);
        *r = NULL;
        }
}

void initTree( TreeNode** r) {

    if (*r != NULL)
        clearTree( &(*r) );

    if( *r == NULL)
        printf("Limpeza com sucesso !!\n"); 
    else    
        printf("Limpeza sem sucesso !!\n"); 
}

Create Node function as requested:

TreeNode* createNode(int n) {

    TreeNode* newNode = (TreeNode*) malloc(sizeof(TreeNode));

    if ( newNode != NULL) {
        newNode->data   = n;
        newNode->left   = 
        newNode->right  = NULL;
        }

    return newNode;
}

Answer 1

乍一看...“ if（* r = NULL）”应该是“ if（* r == NULL）”

Answer 2

On second look, I don't see the crash, but I see a memory leak. Think what happen within the same function with novono if (*r == NULL) was false. I would recommend you to forget this code and try to write it again from scratch and try to avoid of pointers to pointers - **something.

instead of:

void insertNode(TreeNode** r, int n)

I woud try:

/* this error handling would be sufficient for the beginner */
void * xmalloc(size_t size) {
   void * ret = malloc(size);
   if (!ret) { 
      printf("error\n");
      exit(1); 
   }
   return ret;
} 

/* returns root of the tree */
TreeNode * insertNode(TreeNode* r, int n) {
   if (!r) return createNode(n);
   ...
   return r;
}

TreeNode * createNode(int n) {
   TreeNode * ret = xmalloc(sizeof(TreeNode));
   ret->left = left->right = 0;
   ret->data = n;
   return ret;        
}

Instead of initTree, just:

....
TreeNode * root = 0;
root = insertNode(root, 10);
root = insertNode(root, 12);
root = insertNode(root, 20);
root = insertNode(root, 14);

Answer 3

if (n < ((*r) -> data));
    insertNode(&((*r) -> left), n);

is equivalent to:

if (n < ((*r) -> data)) {
    ;
}
insertNode(&((*r) -> left), n);

So very likely NOT what you want.

(GCC with -Wempty-body (included in -Wextra ) would have warned you about it.)