# Print All Leaf Nodes of a Binary Tree

Print All Leaf Nodes of a Binary Tree” is a basic problem of tree data structure. Here, we are given a binary tree and our task is to print all leaf nodes of given binary tree from left to right.

Leaf Nodes: Leaf Nodes are those nodes/vertices of a tree, which have no children.

A root node is considered to be a leaf node if there are no children of it.

Here, to print leaf nodes of a binary tree, we will modify the existing recursive preorder traversal algorithm.

The steps required to print all leaf Nodes of a Binary Tree are as follows:

1. If root is NULL, then return.
2. If root is leaf node, print the data.
3. If left or right child exists of root node, then call function for left and right child of the node recursively.

#### C++ Program to print all leaf nodes of a binary tree is as follows:

```/* C++ Program to Print all leaf nodes of a Binary Tree */
#include<bits/stdc++.h>
using namespace std;

typedef struct Node
{
int data;
struct Node *left;
struct Node *right;
Node(int ele)
{
data = ele;
left = NULL;
right = NULL;
}
} Node;

/* Function to Print all leaf nodes of a binary tree */
void printLeafNodes(Node *root)
{
/* If root is empty, return */
if(root == NULL)
return;

/* If root is leaf node, print data */
if(root -> left == NULL && root -> right == NULL)
cout<<root -> data << " ";

/* If there exists left child, recursively call left subtree */
if(root -> left)
printLeafNodes(root -> left);

/* If there exists right child, recursively call right subtree */
if(root -> right)
printLeafNodes(root -> right);
}

int main()
{
/* Creating a Binary tree and inserting some nodes in it */
Node *root = NULL;

root = new Node(1);
root -> left = new Node(2);
root -> right = new Node(3);
root -> left -> left = new Node(4);
root -> left -> right = new Node(5);
root -> right -> left = new Node(6);
root -> right -> right = new Node (7);
root -> left -> right -> left = new Node(8);
root -> right -> left -> right = new Node(9);

/* Calling function to print all leaf nodes of a Binary Tree */
cout<<"The Leaf Nodes of the Tree are ";
printLeafNodes(root);
}
```

OUTPUT:

`The Leaf Nodes of the Tree are 4 8 9 7`

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