Binary tree in C | with simple code

Binary Tree
A tree whose elements have at most 2 children is called a binary tree. Since each element in a binary tree can have only 2 children, we typically name them the left and right child.

 #include <stdio.h>
 #include <stdlib.h>
 struct BTnode
 {
    int keyVal;
    struct BTnode *leftNode;
    struct BTnode *rightNode;
 };
 struct BTnode *getNode(int value)
 {
    struct BTnode *newNode = malloc(sizeof(struct BTnode));
    newNode->keyVal = value;
    newNode->leftNode = NULL;
    newNode->rightNode = NULL;
    return newNode;
 }

 struct BTnode *insert(struct BTnode *rootNode, int value)
 {
    if (rootNode == NULL)
        return getNode(value);
    if (rootNode->keyVal < value)
        rootNode->rightNode = insert(rootNode->rightNode, value);
    else if (rootNode->keyVal > value)
        rootNode->leftNode = insert(rootNode->leftNode, value);
    return rootNode;
  }

  void insertorder(struct BTnode *rootNode)
  {
    if (rootNode == NULL)
        return;
    insertorder(rootNode->leftNode);
    printf("%d  ", rootNode->keyVal);
    insertorder(rootNode->rightNode);
  }
  int main()
  {
    printf(" Binary Tree is : ");
    struct BTnode *rootNode = NULL;
    rootNode = insert(rootNode, 7);
    rootNode = insert(rootNode, 4);
    rootNode = insert(rootNode, 8);
    rootNode = insert(rootNode, 1);
    rootNode = insert(rootNode, 5);
    rootNode = insert(rootNode, 2);
    rootNode = insert(rootNode, 9);
    rootNode = insert(rootNode, 3);
    insertorder(rootNode);
    return 0;
  }

When the above program is executed, it produces following results --<\b>

   Binary Tree is : 1  2  3  4  5  7  8  9