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C Programming Exercises

C Exercises: Delete a node from the middle of a circular linked list

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C Linked List : Exercise-27 with Solution

Write a program in C to delete a node from the middle of 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 : 5                                                                                    
 Input data for node 3 : 8                                                                                    
                                                                                                              
 Data entered in the list are :                                                                               
 Data 1 = 2                                                                                                   
 Data 2 = 5                                                                                                   
 Data 3 = 8                                                                                                   
                                                                                                              
 Input the position to delete the node : 3                                                                    
                                                                                                              
 The deleted node is : 8                                                                                      
 After deletion the new list are :                                                                            
 Data 1 = 2                                                                                                   
 Data 2 = 5  

C Code:

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

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

struct node *tail,*p,*q,*store; 

void ClListcreation(int n);
void ClListDeleteMiddle(int pos);
void displayClList(int a);

int main()
{
    int n,num1,a,pos;
    stnode = NULL;
	printf("\n\n Circular Linked List : Delete node from the middle of a circular linked list :\n");
	printf("-----------------------------------------------------------------------------------\n");	   	

    printf(" Input the number of nodes : ");
    scanf("%d", &n);
    ClListcreation(n); 
    a=1;
    displayClList(a);
	printf("\n Input the position to delete the node : ");
	scanf("%d",&pos);	
    ClListDeleteMiddle(pos);  	
    a=2;
    displayClList(a);	
    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
    }
}

void ClListDeleteMiddle(int pos)
{
        int delNode,k=1;
        delNode=pos;
        p=stnode;
        while(k!=delNode)
        {
            q=p;
            p=p->nextptr;
            k++;
        }
        q->nextptr=p->nextptr;
        printf("\n The deleted node is : %d",p->num);
        free(p);
}

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 deletion the new list are :\n");   
        }        
        do {
            printf(" Data %d = %d\n", n, tmp->num);

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

Flowchart :

Flowchart: Delete node from the middle of a circular linked list

ClListcreation() :

Flowchart: Delete node from the middle of a circular linked list

ClListDeleteMiddle() :

Flowchart: Delete node from the middle of a circular linked list

displayClList() :

Flowchart: Delete node from the middle of a circular linked list

C Practice online:


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

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

struct node *tail,*p,*q,*store; 

void ClListcreation(int n);
void ClListDeleteMiddle(int pos);
void displayClList(int a);

int main()
{
    int n,num1,a,pos;
    stnode = NULL;
	printf("\n\n Circular Linked List : Delete node from the middle of a circular linked list :\n");
	printf("-----------------------------------------------------------------------------------\n");	   	

    printf(" Input the number of nodes : ");
    scanf("%d", &n);
    ClListcreation(n); 
    a=1;
    displayClList(a);
	printf("\n Input the position to delete the node : ");
	scanf("%d",&pos);	
    ClListDeleteMiddle(pos);  	
    a=2;
    displayClList(a);	
    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
    }
}

void ClListDeleteMiddle(int pos)
{
        int delNode,k=1;
        delNode=pos;
        p=stnode;
        while(k!=delNode)
        {
            q=p;
            p=p->nextptr;
            k++;
        }
        q->nextptr=p->nextptr;
        printf("\n The deleted node is : %d",p->num);
        free(p);
}

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 deletion the new list are :\n");   
        }        
        do {
            printf(" Data %d = %d\n", n, tmp->num);

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

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