Menu driven program for all operations on doubly linked list in C

A Linked List is a linear data structure that consists of two parts: one is the data part and the other is the address part. A Doubly Linked List in contains three parts: one is the data part and the other two are the address of the next and previous node in the list. In this article, all the common operations of a doubly linked list is discussed in one menu-driven program.

Operations to be performed:

• traverse(): To see the contents of the linked list, it is necessary to traverse the given doubly linked list. The given traverse() function traverses and prints the content of the doubly linked list.
• insertAtFront(): This function simply inserts an element at the front/beginning of the doubly linked list.
• insertAtEnd(): This function inserts an element at the end of the doubly linked list.
• insertAtPosition(): This function inserts an element at a specified position in the doubly linked list.
• deleteFirst(): This function simply deletes an element from the front/beginning of the doubly linked list.
• deleteEnd(): This function simply deletes an element from the end of the doubly linked list.
• deletePosition(): This function deletes an element from a specified position in the doubly linked list.

Below is the implementation of the above operations:

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;
}

Output:

Menu:

Insertion at the starting:

Insertion at the end:

Insertion at specific position:

Print the Linked List:

Delete the first and last element with choice 5 and 6: