Implement all operations on the circular linked list

Singly Linked-List Operations in C

This code demonstrates various operations on a singly linked-list in C.

#include <stdio.h>
#include <stdlib.h>

struct node
{
    int data;
    struct node *next;
} *head = NULL, *travel, *ptr;

// Function to insert a node at the end of the linked-list
void InsertAtEnd(int data)
{
    int new_data = data;
    struct node *new_node = (struct node *)malloc(sizeof(struct node));
    struct node *last;
    travel = head;
    last = head;
    new_node->data = new_data;
    if (head == NULL)
    {
        head = new_node;
        new_node->next = head;
        return;
    }
    else
    {
        while (last->next != head)
        {
            last = last->next;
        }
    }
    last->next = new_node;
    new_node->next = head;
}

// Function to insert a node at the beginning of the linked-list
void InsertAtBegin(int data)
{
    struct node *new_node, *last = head;
    new_node = (struct node *)malloc(sizeof(struct node));
    new_node->data = data;
    if (head == NULL)
    {
        new_node->next = head;
        head = new_node;
    }
    while (last->next != head)
    {
        last = last->next;
    }
    new_node->next = last->next;
    last->next = new_node;
    head = new_node;
}

// Function to insert a node before a specified node
void add_before()
{
    struct node *cur, *pre;
    cur = head;
    pre = head;
    int loc, new_data;
    ptr = (struct node *)malloc(sizeof(struct node));
    printf("\\nEnter the data that before you want to add the node::");
    scanf("%d", &loc);
    printf("Enter the data to add in new node::");
    scanf("%d", &new_data);
    ptr->data = new_data;
    while (cur->data != loc)
    {
        pre = cur;
        cur = cur->next;
    }
    pre->next = ptr;
    ptr->next = cur;
}

// Function to delete the first node of the linked-list
void del_begin()
{
    struct node *ptr;
    if (head == NULL)
    {
        printf("\\nUNDERFLOW\\n");
    }
    else if (head->next == head)
    {
        head = NULL;
        free(head);
        printf("\\nNode Deleted\\n");
    }
    else
    {
        ptr = head;
        while (ptr->next != head)
            ptr = ptr->next;
        ptr->next = head->next;
        free(head);
        head = ptr->next;
        printf("\\nNode Deleted\\n");
    }
}

// Function to delete the last node of the linked-list
void del_last()
{
    struct node *pre = head, *cur = head;
    if (head == NULL)
    {
        printf("\\nLinked-List is empty");
    }
    while (cur->next != head)
    {
        pre = cur;
        cur = cur->next;
    }
    pre->next = cur->next;
    free(cur);
    cur = NULL;
}

// Function to delete a specified node from the linked-list
void del_specified()
{
    struct node *cur=head,*pre=head;
    int val;
    printf("ENTER DATA THAT YOU WANT TO DELETE::");
    scanf("%d",&val);
    if(head==NULL)
    {
        printf("Linked-List is empty.\\n");   
    }
    else if(cur->next==head)
    {
        free(cur);
    }
    while (cur->data!=val)
    {
        pre=cur;
        cur=cur->next;
    }
    pre->next=cur->next;
    free(cur);
    cur=NULL;
}

// Function to print the linked-list
void print()
{
    struct node *last;
    last = head;
    if (last == NULL)
    {
        printf("Linked-List is empty.\\n");
    }
    else
    {
        while (last->next != head)
        {
            printf("%d ", last->data);
            last = last->next;
        }
        printf("%d ", last->data);
    }
}

// Main function
void main()
{
    int choice, data;
    while (1)
    {
        printf("\\nSELECT YOUR CHOICE::");
        printf("\\n1.INSERT NODE AT END::");
        printf("\\n2.INSERT NODE AT BEGINNING::");
        printf("\\n3.INSERT NEW-NODE BEFORE SPECIFIED NODE::");
        printf("\\n4.DELETE FIRST NODE::");
        printf("\\n5.DELETE LAST NODE::");
        printf("\\n6.PRINT LIST::");
        printf("\\n7.DELETE SPECIFIED NODE");
        printf("\\n8.Exit");
        scanf("%d", &choice);
        switch (choice)
        {
        case 1:
            printf("Enter the data to add in new node::");
            scanf("%d", &data);
            InsertAtEnd(data);
            break;
        case 2:
            printf("Enter the data to add in new node::");
            scanf("%d", &data);
            InsertAtBegin(data);
            break;
        case 3:
            add_before();
            break;
        case 4:
            del_begin();
            break;
        case 5:
            del_last();
            break;
        case 6:
            print();
            break;
        case 7:
            del_specified();
            break;
        case 8:
            exit(0);
        default:
            break;
        }
    }
}
    

This code implements various operations on a singly linked-list, including inserting nodes at the end and beginning, inserting before a specified node, deleting nodes, and printing the linked-list.

Feel free to experiment with this code and understand how each singly linked-list operation is implemented!