Count the number of leaves in a tree

#include<stdio.h>
struct binarysearchtree{
        int data;
        struct binarysearchtree* left;
        struct binarysearchtree* right;
};
typedef struct binarysearchtree* tree;

int count_leaves(tree T)
{
        if(T==NULL)
            return 0;
        else if(T->left==NULL && T->right==NULL)
            return 1;
        else
            return count_leaves(T->left)+count_leaves(T->right);
}