Binary Search Tree in C – Create and Display Nodes

A binary search tree in C is a special type of binary tree where each node follows a specific order: left child < parent < right child. This structure is useful for efficient searching, insertion, and deletion operations.

In this article, we will write a C program that creates a binary search tree (BST) by inserting elements provided by the user and then displaying the BST using in-order traversal.

This guide is perfect for students learning data structures and C programming.

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What is a Binary Search Tree?

A binary search tree (BST) is a data structure in which:

• Each node has at most two children.
• Left child contains values less than the node.
• Right child contains values greater than the node.

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C Program: Binary Search Tree in C

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

struct Node {
    int data;
    struct Node* left;
    struct Node* right;
};

struct Node* createNode(int value) {
    struct Node* newNode = (struct Node*)malloc(sizeof(struct Node));
    newNode->data = value;
    newNode->left = NULL;
    newNode->right = NULL;
    return newNode;
}

struct Node* insert(struct Node* root, int value) {
    if (root == NULL) {
        return createNode(value);
    }

    if (value < root->data) {
        root->left = insert(root->left, value);
    } else if (value > root->data) {
        root->right = insert(root->right, value);
    }

    return root;
}

void inOrder(struct Node* root) {
    if (root != NULL) {
        inOrder(root->left);
        printf("%d ", root->data);
        inOrder(root->right);
    }
}

int main() {
    struct Node* root = NULL;
    int values[] = {50, 30, 70, 20, 40, 60, 80};
    int n = sizeof(values)/sizeof(values[0]);

    for (int i = 0; i < n; i++) {
        root = insert(root, values[i]);
    }

    printf("In-order traversal of Binary Search Tree:\n");
    inOrder(root);

    return 0;
}

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Explanation of the Program

• createNode(): Allocates memory and initializes a new node.
• insert(): Recursively inserts a value into the correct location in the BST.
• inOrder(): Performs in-order traversal (Left → Root → Right) to display sorted tree elements.

This binary search tree in C is built using recursion and dynamic memory allocation.

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Applications of Binary Search Tree in C

• Fast searching and retrieval of data
• Implementation of associative arrays
• Used in databases and file systems