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

Delete from 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. You want to remove the first song from the playlist.

🎯 Goal: Build a program that creates a doubly linked list with three songs, then deletes the first song from the list, and finally prints the updated playlist.

📋 What You'll Learn

Create a doubly linked list with exactly three nodes containing the song titles: "Song1", "Song2", and "Song3"

Create a pointer variable called head that points to the first node

Write a function called deleteFromBeginning that deletes the first node of the doubly linked list

Print the updated list from the head to the end after deletion

💡 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 list operations is fundamental for software developers working with dynamic data structures and memory management.

1

Create the doubly linked list with three songs

Create a struct called Node with members char title[20], struct Node *prev, and struct Node *next. Then create three nodes with titles "Song1", "Song2", and "Song3". Link them to form a doubly linked list. Create a pointer called head that points to the first node.

DSA C

// Define struct Node and create three linked nodes with titles
// Link nodes to form doubly linked list
// Create pointer head pointing to first node

Hint

Use malloc to create nodes and strcpy to set titles. Link nodes by setting prev and next pointers.

2

Create a function to delete the first node

Create a function called deleteFromBeginning that takes a pointer to Node * called head and deletes the first node of the doubly linked list. Update head to point to the new first node. Handle the case when the list is empty or has only one node.

DSA C

#include 
#include 
#include 

typedef struct Node {
    char title[20];
    struct Node *prev;
    struct Node *next;
} Node;

// Write function deleteFromBeginning here

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

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

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

    strcpy(third->title, "Song3");
    third->prev = second;
    third->next = NULL;

    // Your code here
}

Hint

Use a double pointer Node **head to modify the head pointer inside the function. Free the old first node after updating the head.

3

Call the delete function to remove the first song

In the main function, call the deleteFromBeginning function with the address of head to delete the first node from the doubly linked list.

DSA C

#include 
#include 
#include 

typedef struct Node {
    char title[20];
    struct Node *prev;
    struct Node *next;
} Node;

void deleteFromBeginning(Node **head) {
    if (*head == NULL) {
        return;
    }
    Node *temp = *head;
    *head = (*head)->next;
    if (*head != NULL) {
        (*head)->prev = NULL;
    }
    free(temp);
}

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

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

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

    strcpy(third->title, "Song3");
    third->prev = second;
    third->next = NULL;

    // Call deleteFromBeginning here
    // Your code here

    return 0;
}

Hint

Call the function with &head to pass the address of the head pointer.

4

Print the updated doubly linked list

Write a while loop in main to print the titles of the songs in the updated doubly linked list starting from head. Print each title followed by " -> ". After the last node, print "NULL".

DSA C

#include 
#include 
#include 

typedef struct Node {
    char title[20];
    struct Node *prev;
    struct Node *next;
} Node;

void deleteFromBeginning(Node **head) {
    if (*head == NULL) {
        return;
    }
    Node *temp = *head;
    *head = (*head)->next;
    if (*head != NULL) {
        (*head)->prev = NULL;
    }
    free(temp);
}

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

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

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

    strcpy(third->title, "Song3");
    third->prev = second;
    third->next = NULL;

    deleteFromBeginning(&head);

    // Print the updated list
    // Your code here

    return 0;
}

Hint

Use a while loop to traverse from head to the end, printing each title followed by " -> ". After the loop, print "NULL".