CODEWITHSUNDEEP
cpointersrecursionbinary-search-tree
Baldr
Baldr

Reputation: 55

Pointers in Binary Search Tree insertions and search in C

I'm new to C programming and this is my first time working on a complicated program. The program will put a phonebook (name and number) in a binary search tree. The question that arises is why I get an error with the Recursion and all pointers that I used in the program. My struct def is also probably wrong.. Would be happy if anyone could point me to the problem and how to solve it.

typedef struct _bstree {
    char * name[60];
    unsigned long phone;
    struct bstree *left;
    struct bstree *right;

}bstree;

typedef struct _bst_node {
    int value;
    struct node* next;
}bst_node;

and here are the functions (I'm not allowed to change the type of the functions or their arguments):

void bst_insert_node(bstree* bst, unsigned long phone, char *name) {
if (bst == NULL) {
    bstree *newNode = (bstree *)malloc(sizeof(bstree));
    newNode->phone = phone;
    strcpy(newNode->name,name);
    newNode->left = NULL;
    newNode->right = NULL;
    }
else if (bst->phone>phone) {
        bst_insert_node(bst->left,phone, name); //ERROR
    }
else {
bst_insert_node(bst->right, phone, name); //ERROR
     }
}



bst_node* find_node(bstree* bst, unsigned long phone) {
if (bst==NULL) {
    printf("Cannot find Number");
    return NULL;
}
//if phone ist root
if (phone== bst->phone)
    return bst;            //ERROR

bstree* searching = NULL;
//left search
searching = find_node(bst->left,phone);   //ERROR
if (searching)
    return searching;        //ERROR

// right search
searching = find_node(bst->right,phone);      //ERROR
if (searching)
    return searching;    //ERROR

if (searching)
    return searching;       //ERROR

return NULL;
}

Upvotes: 1

Views: 1153

Answers (2)

DrPrItay
DrPrItay

Reputation: 838

try this code buddy 

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

typedef struct _bst_node 
{
    char          name[60];
    unsigned long phone;
} bst_node;

typedef struct _bstree 
{
    bst_node key;
    struct _bstree * left;
    struct _bstree * right;
} bstree;


static inline bstree * create_node(unsigned long phone, char * name)
{

        bstree * newNode = (bstree *) malloc(sizeof(bstree));
        newNode->key.phone = phone;
        strcpy(newNode->key.name, name);
        newNode->left = NULL;
        newNode->right = NULL;

        return newNode;
}

void bst_insert_node(bstree * bst, unsigned long phone, char * name) 
{
    if (bst == NULL) 
    {
        return;
    }

    if (bst->key.phone > phone)
    {
        if (bst->left == NULL)
        {
            bst->left = create_node(phone, name);
            return;
        }

        bst_insert_node(bst->left, phone, name);
    }
    else
    {
        if (bst->right == NULL)
        {
            bst->right = create_node(phone, name);
            return;
        }

        bst_insert_node(bst->right, phone, name);
    }
}



bst_node * find_node(bstree* bst, unsigned long phone) 
{
    if (bst == NULL)
    {
        return NULL;
    }

    if(bst->key.phone > phone)
    {
        return find_node(bst->left, phone);
    }
    else if (bst->key.phone < phone)
    {
        return find_node(bst->right, phone);
    }

    return &(bst->key);
}


void print_tree(bstree * bst, int level)
{
    int temp = 0;
    while(temp < level)
    {
        printf("-");
        ++temp;
    }

    printf(" (%ld-%s)\n", bst->key.phone, bst->key.name);

    if (bst->left != NULL)
    {
        print_tree(bst->left, level + 1);
    }

    if (bst->right != NULL)
    {
        print_tree(bst->right, level + 1);
    }
}

Upvotes: 0

Gaurav Sehgal
Gaurav Sehgal

Reputation: 7542

typedef struct _bstree {
char * name[60];
unsigned long phone;
struct bstree *left;
struct bstree *right;
}bstree;

Why does your tree structure have left and right.The nodes of the tree should have left and right and not the tree itself.The tree structure should just have a root node.

typedef struct _bst_node {
char name[60];
unsigned long phone;
struct _bst_node *left;
struct _bst_node *right;
}bst_node;

and then the tree structure

typedef struct _bstree {
bst_node *root; //this will point to the root node of the tree and will be NULL if the tree is emty.
}bstree;

Your insert() function should take bstree as input and insert a new bst_node in the tree.Remeber your root is bsttree::root and not bsttree itself.

 void bst_insert_node(bstree* bst, unsigned long phone, char *name)
 {
      //insert new node
 }

Upvotes: 2

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