Tutorial for Tree Data Structure in C

Could someone direct me to some tutorial on Tree Data Structures using C. I tried googling bu开发者_高级运维t most implementations are for C++ or Java.If someone can point me to some online tutorials that are in C it would be great.

Thanks..

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Generic tree-traversal methods: http://en.wikipedia.org/wiki/Tree_traversal (see right sidebar for a huge list of algorithms to choose from).

Some tutorials:

• http://randu.org/tutorials/c/ads.php
• http://www.ehow.com/how_2056293_create-binary-tree-c.html

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Here's a bit of tutorial code from a couple of decades ago. In fact, it's been lying around so long, I don't remember where it came from or who wrote it (could have been me, but I'm really not sure). Theoretically it's a bit non-portable, using strdup, which isn't part of the standard library, though most compilers have/supply it.

/* Warning: untested code with no error checking included. */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

/* A tree node. Holds pointers to left and right sub-trees, and some data (a string).
 */
typedef struct node {
    struct node *left;
    struct node *right;
    char *string;
} node;

node *root; /* pointers automatically initialized to NULL */

int insert(const char *string, node *root) {

    /* Add a string to the tree. Keeps in order, ignores dupes.
     */
    int num = strcmp(root->string, string);
    node *temp;

    for(;;) {
        if ( 0 == num)
            /* duplicate string - ignore it. */
            return 1;
        else if (-1 == num) {
            /* create new node, insert as right sub-tree.
             */
            if ( NULL == root -> right ) {
                temp = malloc(sizeof(node));
                temp -> left = NULL;
                temp -> right = NULL;
                temp -> string = strdup(string);
                return 2;
            }
            else
                root = root -> right;
        }
        else if ( NULL == root ->left ) {
            /* create new node, insert as left sub-tree.
             */
            temp = malloc(sizeof(node));
            temp -> left = NULL;
            temp -> right = NULL;
            temp -> string = strdup(string);
            return 2;
        }
        else
            root = root -> left;
    }
}


void print(node *root) {   
    /* in-order traversal -- first process left sub-tree.
     */
    if ( root -> left != NULL )
        print(root->left);
    /* then process current node.
     */
    fputs(root->string, stdout);

    /* then process right sub-tree
     */
    if ( root->right != NULL )
        print(root->right);
}

int main() {

    char line[100];

    /* Let user enter some data. Enter an EOF (e.g., ctrl-D or F6) when done.
     */
    while ( fgets(line, 100, stdin))
        insert(line, root);

    /* print out the data, in order
     */
    print(root);
    return 0;
}

---

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

struct binary_node {
        struct binary_node *left;
        struct binary_node *right; int value;
};

typedef struct binary_node NODE;

int search(NODE *temp, int data)
{
        int found = 0;

#if 0
        while (temp == NULL) {
                if (temp->value == data) {
                        found = 1;
                        break;
                }
                else if (temp->value > data)
                        temp = temp->left;
                else if (temp->value < data)
                        temp = temp->right;
        }
        return found;
#endif

        if (temp == NULL)
                return 0;
        else if (temp->value == value)
                return 1;
        else if (temp->value > data)
                return search(temp->left, data);
        else if (temp->value < data)
  }




NODE *del(NODE *root, int val)
{
        if (root = NULL)
                return ;
        if (val < root->val)
                root->left = delete(root->left, val);
        else if (val > root->val)
                root->right = delete(root->right, val);

        else {
                if (root->left == NULL && root->right == NULL) {
                        temp = root;
                        free(temp);
                        root = NULL;
                }
                else if (root->left == NULL) {
                        temp = root;
                        root = root->right;
                        free(temp);
                }
                else if (root->right == NULL) {
                        temp = root;
                        root = root->left;
                        free(temp);
                }
                else {
                        temp = min(root->right);
                        root->data = temp->data;
                        root->right = delete(root->right, temp->data);
                }
        }

                return root;
}



NODE *insert_node(NODE *node, int val)
{

        if (*node == NULL) {
                node = (NODE *) malloc (sizeof(NODE));
                node->left = NULL;
                node->right = NULL;
                node->value = val;
        }

        if (node->value > val)
                node->left = insert_node(node->left, val);
        else if (node->value < val)
                node->right = insert_node(node->right, val);
        else
                printf("Discarding the data as it already exists in node\n");

        return node;
}

}
int main()
{

        NODE *root = NULL;

        root = insert_node(root, 50);
        insert_node(root, 4);
        insert_node(root, 14);
        insert_node(root, 44);
        insert_node(root, 24);
        insert_node(root, 34);
        insert_node(root, 74);
        insert_node(root, 54);
        insert_node(root, 64);

        print_order(&root);

        search(&root, 34);
        del(&root);

        return 0;
}