Problem searching in my Binary Search Tree - c

Question

Problem is function bin_search. it works steady on function insert. However, it gets frozen on function search. I think if it's fine on insert, it should be fine on search, but it isn't. Here is my code...
"bst.h":
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
typedef struct Node {
int key;
void *data;
struct Node *left, *right;
void (*destroy)(void *data);
} node;
typedef struct Tree {
node *head;
char name;
} tree;
#define key(node) node->key
#define data(node) node->data
#define left(node) node->left
#define right(node) node->right
#define destroy(node) node->destroy
#define tree_head(tree) tree->head
"functions.c":
#include "bst.h"
int bin_search(node *curr, int key, int cnt, node **found) {
cnt++; printf("cnt+\n");
if (curr == NULL) {
return -1;
} else if (curr->key == key) {
printf("curr_key = key\n"); return cnt;
}
if (curr->key < key) {
printf("curr_key < key\n");
if (curr->right == NULL) {
*found = curr;
return -(cnt + 1);
}
return bin_search(curr->right, key, cnt, found);
} else {
printf("curr_key > key\n");
if (curr->left == NULL) {
*found = curr;
return -(cnt + 1);
}
return bin_search(curr->left, key, cnt, found);
}
}
int insert(tree *root, int key, void *data, void (*destroy)(void *data)) {
if (root->head == NULL) {
node* new_node = (node *)malloc(sizeof(node));
left(new_node) = NULL; right(new_node) = NULL; destroy(new_node) = destroy; key(new_node) = key; data(new_node) = data;
tree_head(root) = new_node;
printf("created first node\n"); return 1;
}
int cnt; node **found;
if ((cnt = bin_search(root->head, key, 0, found)) < 0) {
node* new_node = (node *)malloc(sizeof(node));
left(new_node) = NULL; right(new_node) = NULL; destroy(new_node) = destroy; key(new_node) = key; data(new_node) = data;
if ((*found)->key < key) {
(*found)->right = new_node;
} else {
(*found)->left = new_node;
}
printf("created a node at %d\n", -cnt); return 1;
} else {
printf("already exists in tree"); return -1;
}
}
int search(tree *root, int key, void **data) {
if (root->head == NULL) {
printf("tree is empty\n"); return -1;
}
int cnt; node **found;
if ((cnt = bin_search(root->head, key, 0, found)) < 0) {
return -1;
} else {
if ((*found)->key < key) {
*data = (*found)->right->data;
} else {
*data = (*found)->left->data;
}
return cnt;
}
}
"main.c":
#include "bst.h"
#define MAX_NUM 8
#define MAX_LEGNTH 200
int main() {
// create a tree
tree root; root.head = NULL; root.name = 'a';
FILE *inpt = fopen("list.txt", "r"); char buffer[MAX_LEGNTH];
int count = 0;
while (fgets(buffer, MAX_LEGNTH, inpt) != NULL) {
printf("adding: %d\n", atoi(buffer)); insert(&root, atoi(buffer), buffer, NULL);
count++;
}
fclose(inpt);
int result; void **found;
result = search(&root, 2, found); printf("%d\n", result); // problem in here!!
return 0;
}
what is the problem with my 'search' function. I can't find it.

Answer 1

Besides the utterly non-standard use of sizeof(void), you are not providing a correct out-parameter to search. The point of the found argument is to receive the node pointer if the prospect key was discovered. This...
int cnt;
node **found; // <== LOOK HERE
if ((cnt = bin_search(root->head, key, 0, found)) < 0) {
is not the way to do that. It should be done like this:
int cnt;
node *found = NULL;
if ((cnt = bin_search(root->head, key, 0, &found)) < 0) {
// ^^^^^^
and all references to found thereafter should be through found->, not (*found)->
This mistake is made in three different places in your code. The last one is semi-broken, but still broken nonetheless.
void **found = (void *)malloc(sizeof(void));
int result = search(&root, 2, found);
printf("%d\n", result);
That should use this:
void *found = NULL;
int result = search(&root, 2, &found);
printf("%d\n", result);
Whether the rest of your code is broken I cannot say, and frankly we're not in the business of being an online-debugger. Use your local debugger tools; that's what they're for. But the items listed above are definitely a problem.