doubly Linked list -Write a menu driven program to perform opration on Doibly linked list in c

// C program for the all operations in

// the Doubly Linked List

#include <stdio.h>

#include <stdlib.h>

 

// Linked List Node

struct node {

    int info;

    struct node *prev, *next;

};

struct node* start = NULL;

 

// Function to traverse the linked list

void traverse()

{

    // List is empty

    if (start == NULL) {

        printf("\nList is empty\n");

        return;

    }

    // Else print the Data

    struct node* temp;

    temp = start;

    while (temp != NULL) {

        printf("Data = %d\n", temp->info);

        temp = temp->next;

    }

}

 

// Function to insert at the front

// of the linked list

void insertAtFront()

{

    int data;

    struct node* temp;

    temp = (struct node*)malloc(sizeof(struct node));

    printf("\nEnter number to be inserted: ");

    scanf("%d", &data);

    temp->info = data;

    temp->prev = NULL;

 

    // Pointer of temp will be

    // assigned to start

    temp->next = start;

    start = temp;

}

 

// Function to insert at the end of

// the linked list

void insertAtEnd()

{

    int data;

    struct node *temp, *trav;

    temp = (struct node*)malloc(sizeof(struct node));

    temp->prev = NULL;

    temp->next = NULL;

    printf("\nEnter number to be inserted: ");

    scanf("%d", &data);

    temp->info = data;

    temp->next = NULL;

    trav = start;

 

    // If start is NULL

    if (start == NULL) {

 

        start = temp;

    }

 

    // Changes Links

    else {

        while (trav->next != NULL)

            trav = trav->next;

        temp->prev = trav;

        trav->next = temp;

    }

}

 

// Function to insert at any specified

// position in the linked list

void insertAtPosition()

{

    int data, pos, i = 1;

    struct node *temp, *newnode;

    newnode = malloc(sizeof(struct node));

    newnode->next = NULL;

    newnode->prev = NULL;

 

    // Enter the position and data

    printf("\nEnter position : ");

    scanf("%d", &pos);

     

 

    // If start==NULL,

    if (start == NULL) {

        start = newnode;

        newnode->prev = NULL;

        newnode->next = NULL;

    }

 

    // If position==1,

    else if (pos == 1) {

      // this is author method its correct but we can simply call insertAtfront() function for this special case

       /* newnode->next = start;

        newnode->next->prev = newnode;

        newnode->prev = NULL;

        start = newnode; */

      // now this is improved by Jay Ghughriwala on geeksforgeeks

      insertAtFront();

    }

 

    // Change links

    else {

      printf("\nEnter number to be inserted: ");

    scanf("%d", &data);

    newnode->info = data;

    temp = start;

        while (i < pos - 1) {

            temp = temp->next;

            i++;

        }

        newnode->next = temp->next;

        newnode->prev = temp;

        temp->next = newnode;

        temp->next->prev = newnode;

    }

}

 

// Function to delete from the front

// of the linked list

void deleteFirst()

{

    struct node* temp;

    if (start == NULL)

        printf("\nList is empty\n");

    else {

        temp = start;

        start = start->next;

        if (start != NULL)

            start->prev = NULL;

        free(temp);

    }

}

 

// Function to delete from the end

// of the linked list

void deleteEnd()

{

    struct node* temp;

    if (start == NULL)

        printf("\nList is empty\n");

    temp = start;

    while (temp->next != NULL)

        temp = temp->next;

    if (start->next == NULL)

        start = NULL;

    else {

        temp->prev->next = NULL;

        free(temp);

    }

}

 

// Function to delete from any specified

// position from the linked list

void deletePosition()

{

    int pos, i = 1;

    struct node *temp, *position;

    temp = start;

 

    // If DLL is empty

    if (start == NULL)

        printf("\nList is empty\n");

 

    // Otherwise

    else {

        // Position to be deleted

        printf("\nEnter position : ");

        scanf("%d", &pos);

 

        // If the position is the first node

        if (pos == 1) {

            deleteFirst(); // im,proved by Jay Ghughriwala on GeeksforGeeks

            if (start != NULL) {

                start->prev = NULL;

            }

            free(position);

            return;

        }

 

        // Traverse till position

        while (i < pos - 1) {

            temp = temp->next;

            i++;

        }

        // Change Links

        position = temp->next;

        if (position->next != NULL)

            position->next->prev = temp;

        temp->next = position->next;

 

        // Free memory

        free(position);

    }

}

 

// Driver Code

int main()

{

    int choice;

    while (1) {

 

        printf("\n\t1  To see list\n");

        printf("\t2  For insertion at"

               " starting\n");

        printf("\t3  For insertion at"

               " end\n");

        printf("\t4  For insertion at "

               "any position\n");

        printf("\t5  For deletion of "

               "first element\n");

        printf("\t6  For deletion of "

               "last element\n");

        printf("\t7  For deletion of "

               "element at any position\n");

        printf("\t8 To exit\n");

        printf("\nEnter Choice :\n");

        scanf("%d", &choice);

 

        switch (choice) {

        case 1:

            traverse();

            break;

        case 2:

            insertAtFront();

            break;

        case 3:

            insertAtEnd();

            break;

        case 4:

            insertAtPosition();

            break;

        case 5:

            deleteFirst();

            break;

        case 6:

            deleteEnd();

            break;

        case 7:

            deletePosition();

            break;

 

        case 8:

            exit(1);

            break;

        default:

            printf("Incorrect Choice. Try Again \n");

            continue;

        }

    }

    return 0;

}