C Exercises: Insert a node at the end of a circular linked list

C Doubly Linked List : Exercise-14 with Solution

Write a program in C to insert a node at the end of a circular linked list.

Visual Presentation:

Sample Solution:

C Code:

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

// Structure definition for a node in a circular linked list
struct node {
    int num;
    struct node *nextptr;
} *stnode; // Global pointer to the start of the circular linked list

// Function prototypes
void ClListcreation(int n);
void ClLinsertNodeAtEnd(int num);
void displayClList(int a);

int main() {
    int n, num1, a;
    stnode = NULL; // Initializing the start pointer of the circular list to NULL

    printf("\n\n Circular Linked List: Insert a node at the end of a circular linked list :\n");
    printf("--------------------------------------------------------------------------------\n");
    printf(" Input the number of nodes : ");
    scanf("%d", &n);

    // Creating a circular linked list
    ClListcreation(n);
    a = 1; // Flag to display the initial list
    displayClList(a);

    printf(" Input the data to be inserted : ");
    scanf("%d", &num1);

    // Inserting a node at the end of the circular linked list
    ClLinsertNodeAtEnd(num1);
    a = 2; // Flag to display the list after insertion
    displayClList(a);

    return 0;
}

// Function to create a circular linked list
void ClListcreation(int n) {
    int i, num;
    struct node *preptr, *newnode;

    if (n >= 1) {
        // Allocating memory for the first node and initializing it
        stnode = (struct node *)malloc(sizeof(struct node));
        printf(" Input data for node 1 : ");
        scanf("%d", &num);
        stnode->num = num;
        stnode->nextptr = NULL;
        preptr = stnode;

        // Loop to create subsequent nodes and link them to form a circular list
        for (i = 2; i <= n; i++) {
            newnode = (struct node *)malloc(sizeof(struct node));
            printf(" Input data for node %d : ", i);
            scanf("%d", &num);
            newnode->num = num;
            newnode->nextptr = NULL;
            preptr->nextptr = newnode;
            preptr = newnode;
        }
        preptr->nextptr = stnode; // Linking the last node with the first node to form a circular list
    }
}

// Function to insert a node at the end of the circular linked list
void ClLinsertNodeAtEnd(int num1) {
    int a = num1;
    struct node *temp = (struct node *)malloc(sizeof(struct node));
    temp->num = a;
    struct node *p = stnode; // Declaring 'p' to iterate through the list

    // Loop to find the last node in the circular list
    while (p->nextptr != stnode) {
        p = p->nextptr;
    }
    p->nextptr = temp;
    temp->nextptr = stnode;
}

// Function to display the circular linked list
void displayClList(int m) {
    struct node *tmp;
    int n = 1;

    if (stnode == NULL) {
        printf(" No data found in the List yet.");
    } else {
        tmp = stnode;
        if (m == 1) {
            printf("\n Data entered in the list are :\n");
        } else {
            printf("\n After insertion the new list are :\n");
        }

        // Loop to display nodes in the circular list
        do {
            printf(" Data %d = %d\n", n, tmp->num);
            tmp = tmp->nextptr;
            n++;
        } while (tmp != stnode);
    }
}

Sample Output:

 Circular Linked List : Insert a node at the end of a circular linked list :                                  
--------------------------------------------------------------------------------                              
 Input the number of nodes : 3                                                                                
 Input data for node 1 : 2                                                                                    
 Input data for node 2 : 5                                                                                    
 Input data for node 3 : 8                                                                                    
                                                                                                              
 Data entered in the list are :                                                                               
 Data 1 = 2                                                                                                   
 Data 2 = 5                                                                                                   
 Data 3 = 8                                                                                                   
 Input the data to be inserted : 9                                                                            
                                                                                                              
 After insertion the new list are :                                                                           
 Data 1 = 2                                                                                                   
 Data 2 = 5                                                                                                   
 Data 3 = 8                                                                                                   
 Data 4 = 9 

Flowchart:

ClListcreation() :

ClLinsertNodeAtEnd() :

displayClList() :

C Programming Code Editor:

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