# Program to Print Alternate Nodes of Linked List

• Write a C program to print alternate nodes of given linked list.
• Function to print alternate nodes of a linked list.

Given a singly linked list, we have to print all alternate nodes of linked list starting from head node. Check the sample example given below for clarification

```Input Linked List
1-->2-->3-->4-->5-->6-->7
Alternate Nodes
1 3 5 7
```

Algorithm to print alternate nodes of linked list
• Initialize an integer variable "counter" with 0. We will use this variable to track the sequence number of any node from head node. Head node's sequence number is 0.
• Using a while loop, we will traverse linked list from head node till (head != NULL) and increment "counter" variable.
• For every node we will check if value of counter is even(counter%2 == 0) then print current node otherwise continue.

In this program, we will write a user defined function "printAlternateNodes" which implements above mentioned algorithm. printAlternateNodes function takes a pointer to the head node of a linked list and print alternate nodes on screen.

```void printAlternateNodes(struct node *head) {
int counter = 0;
printf("\nPrinting Alernate nodes of Linked List\n");
while(head != NULL) {
if (counter%2 == 0) {
printf(" %d ", head->data);
}
counter++;
}
}
```

## C program to print alternate nodes of a singly linked list

```#include <stdio.h>
#include <stdlib.h>

/* A structure of linked list node */
struct node {
int data;
struct node *next;

void initialize(){
}

/*
Given a Inserts a node in front of a singly linked list.
*/
void insert(int num) {
/* Create a new Linked List node */
struct node* newNode = (struct node*) malloc(sizeof(struct node));
newNode->data  = num;
/* Next pointer of new node will point to head node of linked list  */
/* make new node as new head of linked list */
printf("Inserted Element : %d\n", num);
}

/* It Prints alternate nodes of a Linked List */
void printAlternateNodes(struct node *head) {
int counter = 0;
printf("\nPrinting Alernate nodes of Linked List\n");
while(head != NULL) {
if (counter%2 == 0) {
printf(" %d ", head->data);
}
counter++;
}
}

/*
Prints a linked list from head node till tail node
*/
void printLinkedList(struct node *nodePtr) {
while (nodePtr != NULL) {
printf("%d", nodePtr->data);
nodePtr = nodePtr->next;
if(nodePtr != NULL)
printf("-->");
}
}

int main() {
initialize();
/* Creating a linked List*/
insert(7);
insert(6);
insert(5);
insert(4);
insert(3);
insert(2);
insert(1);

return 0;
}
```
Output
```Inserted Element : 7
Inserted Element : 6
Inserted Element : 5
Inserted Element : 4
Inserted Element : 3
Inserted Element : 2
Inserted Element : 1