Number of leaves in binary search tree in C - c

Question

I am a beginner and working on a C binary search tree.I am trying to do a method that will return the number of leaves in my tree.By leaves I mean a node(parent) that has no child(left/right) Heres my tree struct:
struct Node {
int value;
struct Node *left;
struct Node *right;
};
typedef struct Node TNode;
typedef struct Node *binary_tree;
It is created like this:
binary_tree NewBinaryTree(int value_root) {
binary_tree newRoot = malloc(sizeof(TNode));
if (newRoot) {
newRoot->value = value_root;
newRoot->left = NULL;
newRoot->right = NULL;
}
return newRoot;
}
I add elements to it like:
void Insert(binary_tree *tree, int val) {
if (*tree == NULL) {
*tree = (binary_tree)malloc(sizeof(TNode));
(*tree)->value = val;
(*tree)->left = NULL;
(*tree)->right = NULL;
} else {
if (val < (*tree)->value) {
Insert(&(*tree)->left, val);
} else {
Insert(&(*tree)->right, val);
}
}
}
My actual method to count the number of leaves:
int nbleaves(binary_tree tree)
{
int nb;
if(tree->right==NULL && tree->left ==NULL){
nb=nb+1;
}
printf("%d",nb);
}
Of course this doesnt work first theres no actual loop,however I tried it it doesnt return any error but 0(ex after adding element 2222 and 3 to the tree this function return 0).I dont know how to do this function.
thank you!

Answer 1

Because you MUST initialize nb.
int nb = 0;
Since nb is uninitialized it contains a "random" or "garbage" value so the behavior you see is because that value can be very large. But there is no way to predict what that value is.
NOTE: Don't be "stingy" with white spaces, don't use too many of them but let your code breath a little.
Compare
if(tree->right==NULL && tree->left ==NULL){
nb=nb+1;
}
with
if ((tree->right == NULL) && (tree->left == NULL)) {
nb = nb + 1;
}

Answer 2

Besides initializing as #iharob pointed out, you just need to recurse on the left and right halves of the tree and add that to your total (as said in the comments). This approach worked for me on my tests so I'm not sure what error you're getting when you tried it. Here's my nbleaves() function:
int nbleaves(binary_tree tree)
{
int nb=0;
if(tree->right==NULL && tree->left ==NULL){
nb=nb+1;
}
else {
if(tree->left!=NULL)
nb += nbleaves(tree->left);
if(tree->right!=NULL)
nb += nbleaves(tree->right);
}
return nb;
}
For example, on this test case:
int main() {
binary_tree root=NULL;
root=NewBinaryTree(5);
Insert(&root,3);
Insert(&root,7);
Insert(&root,2);
Insert(&root,8);
Insert(&root,6);
Insert(&root,1);
Insert(&root,4);
Insert(&root,9);
traverse(root); /*Just a function I created for testing*/
printf("%d\n",nbleaves(root));
free_tree(root); /*Also a function I wrote*/
return 0;
}
It produces this output:
5: 3 7
3: 2 4
2: 1 NULL
1: NULL NULL
4: NULL NULL
7: 6 8
6: NULL NULL
8: NULL 9
9: NULL NULL
4
The last line is the leaves count and the rest are outputs of traverse().
For my full program: https://repl.it/Epud/0