Can't returning a tree node when is found

Question

How can I return a tree node when I found it?

So, I have a binary tree and, when I search in the tree what I searched for was found I want to return the pointer to that node, so I can usa that node in other function. There is my search function:

Tnode *Tsearch(Tnode *r, char *word) {
    if(r == NULL) {
        printf("%s NOT FOUND\n", word);
        return NULL;
    }
    int comp = strcasecmp(r->word, word);
    if( comp == 0) {
        printf("%s FOUND\n", r->word);
        return r;
    }
    else if( comp > 0) {
        Tsearch(r->left, word);
    }
    else if( comp < 0) {
        Tsearch(r->right, word);
    }
    return 0;
}

My problem is that when I try to use the return of the function Tsearch it doesn't work and I really can't understand why and how to solve it.

The function where I want to use that returned node from the search function is the following:

int Tsearch_ref(Tnode *r, char (*words)[30]) {
    if(r == NULL) {
        return 0;
    }
    printf("%s, %d", words[0], (int)strlen(words[0]));
    Tsearch(r,words[0]);
    auxT = Tsearch(r,words[0]);
    Lnode *aux = auxT->head;
    printf("Title: %s\n", ((Book *)aux->ref)->title);
    while(aux != NULL) {
        aux_arr[i].ref=aux->ref;
        printf("Title: %s\n", ((Book *)aux_arr[i].ref)->title);
        printf("%p\n", &(aux_arr[i].ref));
        aux = aux->next;
        i++;
    }
}

This function is not complete because I was trying to solve the return problem, but basically I want to take that tree node that have a list inside and put that list into a temporary array.

The structures are the following:

typedef struct {
    char *title;
    char isbn13[ISBN13_SIZE];
    char *authors;
    char *publisher;
    int year;
} Book;

typedef struct lnode {
    struct lnode *next;
    void *ref;
} Lnode;


typedef struct tnode {
    struct tnode *left;
    struct tnode *right;
    char *word;
    Lnode *head;
} Tnode;

It's my first question here in StackOverflow, so if you need any more info about anything I will obviously provide it.

Thanks in advance!

Answer 1

You need to change the recursive calls to Tsearch to actually return the found node. So, instead of this code:

else if( comp > 0) {
    Tsearch(r->left, word);
}
else if( comp < 0) {
    Tsearch(r->right, word);
}

do this:

else if( comp > 0) {
    return Tsearch(r->left, word);
}
else if( comp < 0) {
    return Tsearch(r->right, word);
}

Note that if your tree is very deep, you may use up the entire call stack and throw an exception.

Answer 2

Why not use while loop?

Tnode *Tsearch(Tnode *r, char *word) {
    Tnode *cur = r;
    int comp;
    while (cur != NULL)
    {
        if ((comp = strcasecmp(cur->word, word)) == 0)
        {
            printf("%s FOUND\n", cur->word);
            return cur;
        }
        else if (comp > 0)
        {
            /* Move to the left child */
            cur = cur->left;
        }
        else
        {
            /* Move to the right child */
            cur = cur->right;
        }
    }
    printf("NOT FOUND\n");
    return NULL;
}