C Program to implement circular linked list.
#include<stdio.h>
#include<malloc.h>
#include<stdlib.h>
struct node
{
int info;
struct node *link;
}*last;
void create_list(int num);
void addatbeg(int num);
void addafter(int num,int pos);
void del(int num);
void display();
void main()
{
int choice,n,m,po,i;
last=NULL;
while(1)
{
printf("1.Create List\n");
printf("2.Add at begining\n");
printf("3.Add after \n");
printf("4.Delete\n");
printf("5.Display\n");
printf("6.Quit\n");
printf("Enter your choice : ");
scanf("%d",&choice);
switch(choice)
{
case 1: printf("How many nodes you want : ");
scanf("%d",&n);
for(i=0; i < n;i++)
{
printf("Enter the element : ");
scanf("%d",&m);
create_list(m);
}
break;
case 2: printf("Enter the element : ");
scanf("%d",&m);
addatbeg(m);
break;
case 3: printf("Enter the element : ");
scanf("%d",&m);
printf("nter the position after which this element is inserted: ");
scanf("%d",&po);
addafter(m,po);
break;
case 4: if(last == NULL)
{
printf("List underflow\n");
continue;
}
printf("Enter the number for deletion : ");
scanf("%d",&m);
del(m);
break;
case 5: display();
break;
case 6: exit(0);
default:printf("Wrong choice\n");
}
}
}
void create_list(int num)
{
struct node *temp;
temp=(node*)malloc(sizeof(struct node));
temp->info = num;
if(last == NULL)
{
last = temp;
temp->link = last;
}
else
{
temp->link = last->link;
last->link = temp;
last = temp;
}
}
void addatbeg(int num)
{
struct node *temp;
temp =(node*)malloc(sizeof(struct node));
temp->info = num;
temp->link = last->link;
last->link = temp;
}
void addafter(int num,int pos)
{
struct node
*temp,*q;
int i;
q = last->link;
for(i=0;i<pos-1;i++)
{
q = q->link;
if(q==last->link)
{
printf("There are less than %d elements\n",pos);
return;
}
}
temp =(node*)malloc(sizeof(struct node) );
temp->link = q->link;
temp->info = num;
q->link = temp;
if(q==last) //Element inserted at the end
last=temp;
}//End of addafter()
void del(int num)
{
struct node *temp,*q;
if( last->link == last && last->info == num) //Only one element
{
temp=last;
last = NULL;
free(temp);
return;
}
q = last->link;
if(q->info == num)
{
temp = q;
last->link = q->link;
free(temp);
return;
}
while(q->link !=last)
{
if(q->link->info==num) //Element deleted in between
{
temp = q->link;
q->link = temp->link;
free(temp);
printf("%d deleted\n",num);
return;
}
q = q->link;
}
if(q->link->info==num) //Last element deleted q->link=last
{
temp = q->link;
q->link = last->link;
free(temp);
last = q;
return;
}
printf("Element %d not found\n",num);
}
void display()
{
struct node *q;
if(last == NULL)
{
printf("List is empty\n");
return;
}
q = last->link;
printf("List is :\n");
while(q != last)
{
printf("%d ", q->info);
q = q->link;
}
printf("%d\n",last->info);
}
