Implement a doubly linked list and perform various operations to understand its properties and applications in C

 #include <stdio.h>

#include <stdlib.h>

// Define the Node structure

struct Node {

    int data;

    struct Node* prev;

    struct Node* next;

};

// Head of the list

struct Node* head = NULL;

// Insert at the beginning

void insertAtBeginning(int data) {

    struct Node* newNode = (struct Node*)malloc(sizeof(struct Node));

    newNode->data = data;

    newNode->prev = NULL;

    newNode->next = head;

    if (head != NULL)

        head->prev = newNode;

    head = newNode;

}

// Insert at the end

void insertAtEnd(int data) {

    struct Node* newNode = (struct Node*)malloc(sizeof(struct Node));

    newNode->data = data;

    newNode->next = NULL;

    if (head == NULL) {

        newNode->prev = NULL;

        head = newNode;

        return;

    }

    struct Node* temp = head;

    while (temp->next != NULL)

        temp = temp->next;

    temp->next = newNode;

    newNode->prev = temp;

}

// Delete a node by value

void deleteByValue(int key) {

    if (head == NULL) {

        printf("List is empty.\n");

        return;

    }

    struct Node* temp = head;

    // If head node itself holds the key

    if (temp->data == key) {

        head = temp->next;

        if (head != NULL)

            head->prev = NULL;

        free(temp);

        return;

    }

    while (temp != NULL && temp->data != key)

        temp = temp->next;

    if (temp == NULL) {

        printf("Node with value %d not found.\n", key);

        return;

    }

    if (temp->next != NULL)

        temp->next->prev = temp->prev;

    if (temp->prev != NULL)

        temp->prev->next = temp->next;

    free(temp);

}

// Traverse the list forward

void traverseForward() {

    struct Node* temp = head;

    printf("Forward: ");

    while (temp != NULL) {

        printf("%d ", temp->data);

        temp = temp->next;

    }

    printf("\n");

}

// Traverse the list backward

void traverseBackward() {

    struct Node* temp = head;

    if (temp == NULL) {

        printf("List is empty.\n");

        return;

    }

    // Go to last node

    while (temp->next != NULL)

        temp = temp->next;

    printf("Backward: ");

    while (temp != NULL) {

        printf("%d ", temp->data);

        temp = temp->prev;

    }

    printf("\n");

}

// Main function to test the operations

int main() {

    insertAtBeginning(10);

    insertAtEnd(20);

    insertAtEnd(30);

    insertAtBeginning(5);

    traverseForward();   // 5 10 20 30

    traverseBackward();  // 30 20 10 5

    deleteByValue(20);

    traverseForward();   // 5 10 30

    deleteByValue(5);

    traverseForward();   // 10 30

    deleteByValue(100);  // Not found

    return 0;

}

Output: