C Program for Insertion at the End of the Singly Linked List

Insertion in singly linked list at the end

Below we are going to look at the program to insert in a singly linked list at the end. Follow the detailed steps and code below to do the same 0

Insertion at the end of the singly linked list using C

Implementation:-

  • Create a new node, assign its data value
  • Since this new node will be the last node its next will be NULL
  • Traverse to the current last node of the linked list
  • Set the current last node’s next to this new node

If the linked list was initially empty and we were entering the first node, change the head from NULL to this new Node.

C Program for Insertion at the end of the Singly Linked List

Declare Head & mark it NULL

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

struct Node* head = NULL;
LL end 1

Create a Node

void insertEnd(struct Node** head, int data){
    
    // since this will be the last node so it will point to NULL
    struct Node* newNode = (struct Node*) malloc(sizeof(struct Node));
    newNode->data = data;
    newNode->next = NULL;
}
LL insertion end 2

If its the first node being entered

void insertEnd(struct Node** head, int data){
    
    // since this will be the last node so it will point to NULL
    struct Node* newNode = (struct Node*) malloc(sizeof(struct Node));
    newNode->data = data;
    newNode->next = NULL;
// if Linked List is empty its is first node being entered if(*head == NULL){ *head = newNode; return; } }
LL end 3

Otherwise Traverse to the current last node

void insertEnd(struct Node** head, int data){
    
    // since this will be the last node so it will point to NULL
    struct Node* newNode = (struct Node*) malloc(sizeof(struct Node));
    newNode->data = data;
    newNode->next = NULL;

    // if Linked List is empty its is first node being entered
    if(*head == NULL){
        *head = newNode;
        return;
    }
// otherwise find the current last node // create another variable to traverse the LL // *head should not be used as we do not want to change head struct Node* temp = *head; // traverse to the last node of Linked List while(temp->next!=NULL) temp = temp->next; // assign last node's next to this newNode temp->next = newNode;
}

Full Program for Insertion at the End of the Singly Linked List:-

Let us look at the full program for it below –

Run

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

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

void insertEnd(struct Node** head, int data){
    
    // since this will be the last node so it will point to NULL
    struct Node* newNode = (struct Node*) malloc(sizeof(struct Node));
    newNode->data = data;
    newNode->next = NULL;

    // if Linked List is empty its is first node being entered
    if(*head == NULL){
        *head = newNode;
        return;
    }
    // otherwise find the current last node
    
    // create another variable to traverse the LL
    // *head should not be used as we do not want to change head
    struct Node* temp = *head;
    
    // traverse to the last node of Linked List
    while(temp->next!=NULL)
        temp = temp->next;
    
    // assign last node's next to this newNode
    temp->next = newNode;
    
    printf("%d inserted at the end\n", data);
}


void display(struct Node* node){

    // as linked list will end when Node is Null
    while(node!=NULL){
        printf("%d ",node->data);
        node = node->next;
    }
    printf("\n");
}

int main()
{
    //creating 4 pointers of type struct Node
    //So these can point to address of struct type variable
    struct Node* head = NULL; 
    struct Node* node2 = NULL; 
    struct Node* node3 = NULL; 
    struct Node* node4 = NULL;

    // allocate 3 nodes in the heap 
    head =  (struct Node*)malloc(sizeof(struct Node)); 
    node2 = (struct Node*)malloc(sizeof(struct Node)); 
    node3 = (struct Node*)malloc(sizeof(struct Node)); 
    node4 = (struct Node*)malloc(sizeof(struct Node));
   
    head->data  = 22; // data set for head node 
    head->next  = node2; // next pointer assigned to address of node2 

    node2->data = 30; 
    node2->next = node3; 

    node3->data = 24;
    node3->next = node4; 

    node4->data = 20;
    node4->next = NULL;

    /*No need for & i.e. address as we do not
    need to change head address
    */
    printf("Linked List Before Operations : "); 
    display(head);
    
    insertEnd(&head,5);
    insertEnd(&head,6);
    insertEnd(&head,7);
    insertEnd(&head,8);

    printf("Linked List After Operations : ");
    display(head);

    return 0; 
}

Output

Linked List Before Operations: 22 30 24 20 
5 inserted at the end
6 inserted at the end
7 inserted at the end
8 inserted at the end
Linked List After Operations : 22 30 24 20 5 6 7 8

Insertion also perform on this places in the Singly Linked List as shown below:-

  1. Insertion at the beginning of the Singly Linked List
  2. Insertion at the nth node of the Singly Linked List