如何将元素插入 BST (DSA) ？

#include<stdio.h>
#include<stdlib.h>
struct node{
   struct node* left;
   int data;
   struct node* right;
};
struct node* createNode(int key){
   struct node * newNode = NULL;
   newNode = malloc(sizeof(struct node));
   newNode->left = NULL;
   newNode->data = key;
   newNode->right = NULL;

   return newNode;
}
void insertNewNode(struct node* root , int key){
    struct node * prev = NULL;
    while(root!=NULL){
        prev = root;
        if(key==root){
            printf("element cannot insert it is present 
                              inside the bst already");
            return ;
        }
        else if(key>root->data)
        {   
                root = root->right;
        }
        else{
            root = root->left;
        }
    }
    struct node * newNode = createNode(key);
    if(key>prev->data){
        prev->right = newNode;
    }
    else{
        prev->left = newNode;
    }
}
void inOrder(struct node* root){
     if(root == NULL){
        return root;
    }
    inOrder(root->left);
    printf("%d",root->data1`1);
    inOrder(root->right);

}
int main(){

    struct node* head1 = createBst(20);
    struct node* head2 = createBst(10);
    struct node* head3 = createBst(30);


    head1->left=head2;
    head1->right=head3;

    insertNewNode(head1,40);
    printf("%d\n",head1->right->right->data);
    inOrder(head1);




    return 0;
}