Insert at Beginning of Doubly Linked List in DSA C - Build from Scratch

Insert at Beginning of Doubly Linked List

📖 Scenario: You are managing a playlist of songs using a doubly linked list. Each song is a node with a title and links to the previous and next songs.Now, you want to add a new song at the beginning of the playlist.

🎯 Goal: Build a doubly linked list and insert a new node at the beginning. Then print the playlist from start to end.

📋 What You'll Learn

Create a struct called Node with char title[50], Node* prev, and Node* next

Create a doubly linked list with two nodes having titles "Song1" and "Song2"

Create a new node with title "NewSong" and insert it at the beginning of the list

Print the playlist titles from the beginning to the end separated by -> and ending with NULL

💡 Why This Matters

🌍 Real World

Doubly linked lists are used in music players, browsers, and other apps to move forward and backward through items efficiently.

💼 Career

Understanding linked lists and pointer manipulation is essential for software developers working with low-level data structures and memory management.

1

Create the initial doubly linked list

Create a struct called Node with char title[50], Node* prev, and Node* next. Then create two nodes with titles "Song1" and "Song2" linked as a doubly linked list. Set head to point to the first node.

DSA C

# Define struct Node and create two linked nodes with titles "Song1" and "Song2"
// Your code here

Hint

Use typedef struct Node to define the node. Use malloc to create nodes. Use strcpy to set titles.

2

Create the new node to insert

Create a new node pointer called newNode using malloc. Set its title to "NewSong". Initialize its prev and next pointers to NULL.

DSA C

#include 
#include 
#include 

typedef struct Node {
    char title[50];
    struct Node* prev;
    struct Node* next;
} Node;

int main() {
    Node* head = (Node*)malloc(sizeof(Node));
    Node* second = (Node*)malloc(sizeof(Node));

    strcpy(head->title, "Song1");
    head->prev = NULL;
    head->next = second;

    strcpy(second->title, "Song2");
    second->prev = head;
    second->next = NULL;

    // Create newNode and set title to "NewSong"
    // Your code here

    return 0;
}

Hint

Use malloc to create newNode. Use strcpy to set the title. Set both pointers to NULL.

3

Insert the new node at the beginning

Insert newNode at the beginning of the doubly linked list. Set newNode->next to head, head->prev to newNode, and update head to point to newNode.

DSA C

#include 
#include 
#include 

typedef struct Node {
    char title[50];
    struct Node* prev;
    struct Node* next;
} Node;

int main() {
    Node* head = (Node*)malloc(sizeof(Node));
    Node* second = (Node*)malloc(sizeof(Node));

    strcpy(head->title, "Song1");
    head->prev = NULL;
    head->next = second;

    strcpy(second->title, "Song2");
    second->prev = head;
    second->next = NULL;

    Node* newNode = (Node*)malloc(sizeof(Node));
    strcpy(newNode->title, "NewSong");
    newNode->prev = NULL;
    newNode->next = NULL;

    // Insert newNode at beginning
    // Your code here

    return 0;
}

Hint

Link newNode to the current head. Update head->prev to newNode. Then update head to newNode.

4

Print the doubly linked list

Use a Node* pointer called temp to traverse the list from head. Print each node's title followed by -> . After the last node, print NULL.

DSA C

#include 
#include 
#include 

typedef struct Node {
    char title[50];
    struct Node* prev;
    struct Node* next;
} Node;

int main() {
    Node* head = (Node*)malloc(sizeof(Node));
    Node* second = (Node*)malloc(sizeof(Node));

    strcpy(head->title, "Song1");
    head->prev = NULL;
    head->next = second;

    strcpy(second->title, "Song2");
    second->prev = head;
    second->next = NULL;

    Node* newNode = (Node*)malloc(sizeof(Node));
    strcpy(newNode->title, "NewSong");
    newNode->prev = NULL;
    newNode->next = NULL;

    newNode->next = head;
    head->prev = newNode;
    head = newNode;

    // Print the list from head
    // Your code here

    return 0;
}

Hint

Use a while loop to print each node's title followed by -> . End with NULL.