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C Exercises: Search an element in a circular linked list

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C Linked List : Exercise-29 with Solution

Write a program in C to search an element in a circular linked list.
Test Data and Expected Output :

Input the number of nodes : 3                                                                                
 Input data for node 1 : 2                                                                                    
 Input data for node 2 : 9                                                                                    
 Input data for node 3 : 1                                                                                    
                                                                                                              
                                                                                                              
 Data entered in the list are :                                                                               
 Data 1 = 2                                                                                                   
 Data 2 = 9                                                                                                   
 Data 3 = 1                                                                                                   
 Input the element you want to find : 7                                                                       
 This element does not exists in 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  

C Code:

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

struct node {
    int num;
    struct node * nextptr;
}*stnode,*ennode;
 

void ClListcreation(int n);
int FindElement(int FindElem, int n);
void displayClList();

int main()
{
    int n,m;
    int i,FindElem,FindPlc;
    stnode = NULL;
    ennode = NULL;
	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;
 
    ClListcreation(n); 
    displayClList();
    printf(" Input the element you want to find : ");
    scanf("%d", &FindElem);   

    FindPlc=FindElement(FindElem,m);
	if(FindPlc<n)
		printf(" Element found at node %d \n\n",FindPlc);
	else
		printf(" This element does not exists in linked list.\n\n");    
    
    return 0;
}

void ClListcreation(int n)
{
    int i, num;
    struct node *preptr, *newnode;

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

        printf(" Input data for node 1 : ");
        scanf("%d", &num);
        stnode->num = num;
        stnode->nextptr = NULL;
        preptr = stnode;
        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;	// next address of new node set as NULL
            preptr->nextptr = newnode;	// previous node is linking with new node
            preptr = newnode;   		// previous node is advanced
        }
        preptr->nextptr = stnode; 		//last node is linking with first node
    }
}

int FindElement(int FindElem, int a)
{
	int ctr=1;
	ennode=stnode;
	while(ennode->nextptr!=NULL)
	{
		if(ennode->num==FindElem)
			break;
		else
			ctr++;
			ennode=ennode->nextptr;
			if (ctr==a+1)
			break;
	}
	return ctr;
}

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");

        do {
            printf(" Data %d = %d\n", n, tmp->num);

            tmp = tmp->nextptr;
            n++;
        }while(tmp != stnode);
    }
}

Flowchart :

Flowchart: Search an element in a circular linked list

ClListcreation() :

Flowchart: Search an element in a circular linked list

FindElement() :

Flowchart: Search an element in a circular linked list

displayClList() :

Flowchart: Search an element in a circular linked list

C Practice online:


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

struct node {
    int num;
    struct node * nextptr;
}*stnode,*ennode;
 

void ClListcreation(int n);
int FindElement(int FindElem, int n);
void displayClList();

int main()
{
    int n,m;
    int i,FindElem,FindPlc;
    stnode = NULL;
    ennode = NULL;
	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;
 
    ClListcreation(n); 
    displayClList();
    printf(" Input the element you want to find : ");
    scanf("%d", &FindElem);   

    FindPlc=FindElement(FindElem,m);
	if(FindPlc<n)
		printf(" Element found at node %d \n\n",FindPlc);
	else
		printf(" This element does not exists in linked list.\n\n");    
    
    return 0;
}

void ClListcreation(int n)
{
    int i, num;
    struct node *preptr, *newnode;

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

        printf(" Input data for node 1 : ");
        scanf("%d", &num);
        stnode->num = num;
        stnode->nextptr = NULL;
        preptr = stnode;
        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;	// next address of new node set as NULL
            preptr->nextptr = newnode;	// previous node is linking with new node
            preptr = newnode;   		// previous node is advanced
        }
        preptr->nextptr = stnode; 		//last node is linking with first node
    }
}

int FindElement(int FindElem, int a)
{
	int ctr=1;
	ennode=stnode;
	while(ennode->nextptr!=NULL)
	{
		if(ennode->num==FindElem)
			break;
		else
			ctr++;
			ennode=ennode->nextptr;
			if (ctr==a+1)
			break;
	}
	return ctr;
}

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");

        do {
            printf(" Data %d = %d\n", n, tmp->num);

            tmp = tmp->nextptr;
            n++;
        }while(tmp != stnode);
    }
}

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