Question

In c++, write a function that prints every other element in a linked list. Assume that it is a member function of a doubly linked list. This means you will need to use pointer operations.

Answer 1

A doubly linked list is a linked list in which navigation is possible in both forward and backward ways. Here "prev" link points to the "next" link of previous element and "next" link points to the "previous" link of next element and each link carries a data field to contain the data.

Please find the solution below. Here we will insert the data in a doubly linked list first then we will print the data inside the linked list.

#include <iostream>
using namespace std;
// doubly linked list node
struct Node {
int data; // to hold an integer value
struct Node *next; // Pointer to next node
struct Node* prev; // Pointer to previous node
};
struct Node* head = NULL;
void insert_operation(int new_data) { // insert function will insert the data at the beginning of the doubly linked list
struct Node* newnode = (struct Node*) malloc(sizeof(struct Node)); // allocating a block of uninitialized memory
newnode->data = new_data;
newnode->prev = NULL;
newnode->next = head;   
if(head != NULL) {
head->prev = newnode ;
}
head = newnode;
}   
void print() { // print() function will print the elements of the doubly linked list
struct Node* ptr;
ptr = head;
while(ptr != NULL) {
cout<< ptr->data <<" ";
ptr = ptr->next;
}
}
int main() {
int len,j;
cout<< "How many integer you want to insert in the linked list ? ";
cin >> len ;
for (int i=0; i<len;i++){
cout<< "Enter the value : ";
cin >> j ;
insert_operation(j);
}
cout<<"The doubly linked list is:\n ";
print();
return 0;
}

OUTPUT: