C Exercises: Search an element in a circular linked list

Last update on March 19 2025 12:37:18 (UTC/GMT +8 hours)

19. Search in Circular Linked List

Write a program in C to search an element in a circular linked list.

Visual Presentation:

Sample Solution:

C Code:

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

// Structure definition for a node in a circular linked list
struct node {
    int num;
    struct node *nextptr;
}*stnode, *ennode;

// Function prototypes
void ClListcreation(int n);
int FindElement(int FindElem, int n);
void displayClList();

int main() {
    int n, m;
    int FindElem, FindPlc;
    stnode = NULL;
    ennode = NULL;

    // User input for the number of nodes
    printf("\n\n Circular Linked List : Search an element in a circular linked list :\n");
    printf("-------------------------------------------------------------------------\n");
    printf(" Input the number of nodes : ");
    scanf("%d", &n);
    m = n;

    // Creating a circular linked list
    ClListcreation(n);
    displayClList();

    // Input for the element to find in the list
    printf(" Input the element you want to find : ");
    scanf("%d", &FindElem);

    // Searching for the element in the list
    FindPlc = FindElement(FindElem, m);
    if (FindPlc < n)
        printf(" Element found at node %d \n\n", FindPlc);
    else
        printf(" This element does not exist in the linked list.\n\n");

    return 0;
}

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

    if (n >= 1) {
        stnode = (struct node *)malloc(sizeof(struct node));

        // Input for the first 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; // Last node linking with the first node to form a circular list
    }
}

// Function to find an element in the circular linked list
int FindElement(int FindElem, int a) {
    int ctr = 1;
    ennode = stnode;

    // Loop to search for the element
    while (ennode->nextptr != NULL) {
        if (ennode->num == FindElem)
            break;
        else {
            ctr++;
            ennode = ennode->nextptr;
            if (ctr == a + 1)
                break;
        }
    }
    return ctr;
}

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

    if (stnode == NULL) {
        printf(" No data found in the List yet.");
    } else {
        tmp = stnode;
        printf("\n\n Data entered in the 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 : Search an element in 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 : 9                                                                                    
                                                                                                              
 Data entered in the list are :                                                                               
 Data 1 = 2                                                                                                   
 Data 2 = 5                                                                                                   
 Data 3 = 9                                                                                                   
 Input the element you want to find : 5                                                                       
 Element found at node 2

Flowchart :

ClListcreation() :

FindElement() :

displayClList() :

For more Practice: Solve these Related Problems:

• Write a C program to search for a specific element in a circular linked list and return its position.
• Write a C program to recursively search for an element in a circular linked list and count the comparisons made.
• Write a C program to search for a user-specified value in a circular linked list and indicate if it is not found.
• Write a C program to locate an element in a circular linked list and then rotate the list so that the found node becomes the head.

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