Insertion operation of Binary Search Tree

// C program to demonstrate insert operation in binary search tree
#include<stdio.h>
#include<stdlib.h>
  
struct node
{
    int key;
    struct node *left, *right;
};
  
//  function to create a new BST node
struct node *newNode(int item)
{
    struct node *temp =  (struct node *)malloc(sizeof(struct node));
    temp->key = item;
    temp->left = temp->right = NULL;
    return temp;
}
  
//  function to do inorder traversal of BST
void inorder(struct node *root)
{
    if (root != NULL)
    {
        inorder(root->left);
        printf("%d \n", root->key);
        inorder(root->right);
    }
}
  
  void preorder(struct node *root)
{
    if (root != NULL)
    {
    	printf("%d \n", root->key);
        preorder(root->left);
        preorder(root->right);
    }
}
 
  void postorder(struct node *root)
{
    if (root != NULL)
    {
        postorder(root->left);
        postorder(root->right);
        printf("%d \n", root->key);
    }
}
 
/*  function to insert a new node with given key in BST */
struct node* insert(struct node* node, int key)
{
    /* If the tree is empty, return a new node */
    if (node == NULL) 
	return newNode(key);
 
    /* Otherwise, recur down the tree */
    if (key < node->key)
        node->left  = insert(node->left, key);
    else if (key > node->key)
        node->right = insert(node->right, key);   
 
    /* return the (unchanged) node pointer */
    return node;
}
  
// Driver Program to test above functions
int main()
{
    /* Let us create following BST
              50
           /     \
          30      70
         /  \    /  \
       20   40  60   80 */
    struct node *root = NULL;
    root = insert(root, 50);
    insert(root, 30);
    insert(root, 20);
    insert(root, 40);
    insert(root, 70);
    insert(root, 60);
    insert(root, 80);
  
    // print inoder traversal of the BST
    printf("Inorder is:\n");
    inorder(root);
    // print preoder traversal of the BST
    printf("Preorder is:\n");
    preorder(root);
    // print postoder traversal of the BST
    printf("Postorder is:\n");
	postorder(root); 
    return 0;
}