Need help for explanation of the code.
Code:
#include <stdio.h>
#include <stdlib.h>
/* A binary tree node has data, pointer to left child
and a pointer to right child */
struct node
{
int data;
struct node* left;
struct node* right;
};
/* Helper function that allocates a new node with the
given data and NULL left and right pointers. */
struct node* newNode(int data)
{
struct node* node = (struct node*)
malloc(sizeof(struct node));
node>data = data;
node>left = NULL;
node>right = NULL;
return(node);
}
/* Given a binary tree, print its nodes according to the
"bottomup" postorder traversal. */
void printPostorder(struct node* node)
{
if (node == NULL)
return;
// first recur on left subtree
printPostorder(node>left);
// then recur on right subtree
printPostorder(node>right);
// now deal with the node
printf("%d ", node>data);
}
/* Given a binary tree, print its nodes in inorder*/
void printInorder(struct node* node)
{
if (node == NULL)
return;
/* first recur on left child */
printInorder(node>left);
/* then print the data of node */
printf("%d ", node>data);
/* now recur on right child */
printInorder(node>right);
}
/* Given a binary tree, print its nodes in inorder*/
void printPreorder(struct node* node)
{
if (node == NULL)
return;
/* first print data of node */
printf("%d ", node>data);
/* then recur on left sutree */
printPreorder(node>left);
/* now recur on right subtree */
printPreorder(node>right);
}
/* Driver program to test above functions*/
int main()
{
struct node *root = newNode(1);
root>left = newNode(2);
root>right = newNode(3);
root>left>left = newNode(4);
root>left>right = newNode(5);
printf("\n Preorder traversal of binary tree is \n");
printPreorder(root);
printf("\n Inorder traversal of binary tree is \n");
printInorder(root);
printf("\n Postorder traversal of binary tree is \n");
printPostorder(root);
getchar();
return 0;
}
The part in which i am stuck in this program is that....say consider in the function printPreorder what happens when when node==NULL.....where does the control flow...all in all if i am able to understand any of the traversal function code be it preorder or any...it could solve my problem.Please help.
