Linked List Insertion

Creating Node:

struct Node
{
    int data;
    struct Node *next;
};

Traversing Function:

void Traversed_link_list(struct Node *ptr)
{
    while (ptr != NULL)
    {
        cout << "Element: " << ptr->data << endl;
        ptr = ptr->next;
    }
}

Insert at the beginning:

struct Node *insert_at_beginning(struct Node *head, int data)
{
    struct Node *ptr;
    ptr = new Node(); // Memory allocation for new  Node
    ptr->next = head;
    ptr->data = data;

    head = ptr;
    return head;
}

Insert at the particular index:

struct Node *insert_at_Index(struct Node *head, int data, int index)
{
    struct Node *ptr;
    ptr = new Node(); // Memory allocation for new Node
    struct Node *p = head;
    int i = 0;
    while (i != index - 1)
    {
        p = p->next;
        i++;
    }
    ptr->data = data;
    ptr->next = p->next;
    p->next = ptr;
    return head;
}

Insert at the End:

struct Node *insert_at_end(struct Node *head, int data)
{
    struct Node *ptr;
    ptr = new Node(); // Memory allocation for new  Node
    ptr->data = data;
    struct Node *p = head;

    while (p->next != NULL)
    {
        p = p->next;
    }
    
    p->next = ptr;
    ptr->next = NULL;
    return head;
}

Linked List Complete Insertion Program:

#include <iostream>	
using namespace std;

struct Node
{
    int data;
    struct Node *next;
};

void Traversed_link_list(struct Node *ptr)
{
    while (ptr != NULL)
    {
        cout <<"Element: " <<ptr->data << endl;
        ptr = ptr->next;
    }
}

// Insert at the beginning
struct Node *insert_at_beginning(struct Node *head, int data)
{
    struct Node *ptr;
    ptr = new Node(); // Memory allocation for new  Node
    ptr->next = head;
    ptr->data = data;

    head = ptr;
    return head;
}

// Insert at the particular index
struct Node *insert_at_Index(struct Node *head, int data, int index)
{
    struct Node *ptr;
    ptr = new Node(); // Memory allocation for new Node
    struct Node *p = head;
    int i = 0;
    while (i != index - 1)
    {
        p = p->next;
        i++;
    }
    ptr->data = data;
    ptr->next = p->next;
    p->next = ptr;
    return head;
}

// Insert at the End
struct Node *insert_at_end(struct Node *head, int data)
{
    struct Node *ptr;
    ptr = new Node(); // Memory allocation for new  Node
    ptr->data = data;
    struct Node *p = head;

    while (p->next != NULL)
    {
        p = p->next;
    }
    p->next = ptr;
    ptr->next = NULL;
    return head;
}

int main()
{
    struct Node *head;
    struct Node *second;
    struct Node *third;
    struct Node *fourth;

    head = new Node();   // Memory allocation
    second = new Node(); // Memory allocation
    third = new Node();  // Memory allocation
    fourth = new Node(); // Memory allocation

    head->data = 23;
    head->next = second;

    second->data = 45;
    second->next = third;

    third->data = 45;
    third->next = fourth;

    fourth->data = 78;
    fourth->next = NULL;

    cout << "Before Inserting..." << endl;
    Traversed_link_list(head);

    int ele;
    cout << "Enter Element " <	< endl;
    cin >> ele;

    head = insert_at_beginning(head, ele);
    cout << "After Inserting element at the Beginning... " << endl;
    Traversed_link_list(head);

    return 0;
}