Binary Search Tree Insertion in C++

1 #include <iostream>
#include <cstdlib>
struct BSTNode{
int v;
struct BSTNode *left,*right;
};

struct BSTNode *root=NULL;

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

void insertion(struct BSTNode **node,int data){
if(*node==NULL){
*node=createNode(data);
}else if(data<(*node)->v){
insertion(&(*node)->left,data);
}else if(data>(*node)->v){
insertion(&(*node)->right,data);
}
}
void traverse(struct BSTNode *node){
if(node!=NULL){
traverse(node->left);
std::cout<<node->v;
traverse(node->right);
}
return;
}
int main(){
int data,ch;
insertion(&root,10);
insertion(&root,16);
insertion(&root,8);
insertion(&root,20);
insertion(&root,21);
traverse(root);
std::cin>>data;
}