I have tried to implement Circular Linked List with features like insertion, deletion at position, then repeated insertion or deletion based on changing position. However there is a case when initially the list is not yet created and I want to insert at position 1. My program should allow this and should give invalid position for other positions for the mentioned case. However whenever I am trying to do this it is giving me segmentation fault during display in the while loop. Please help. My code is :
#include <stdio.h>
#include <conio.h>
#include <stdlib.h>
struct node
{
int data;
struct node *next;
};
typedef struct node node;
node *head;
int count=0;
void insert(int d,int pos)
{
if((pos==(count+1))||(head==NULL))
{
addnode(d);
}
else
{
if(pos==1)
{
node *newnode = (node *)malloc(sizeof(node));
newnode->data = d;
newnode->next = head;
head = newnode;
tail->next = newnode;
}
else
{
int a = 1;
node *temp = head;
while(a!=(pos-1))
{
temp = temp->next;
a++;
}
node *newnode = (node *)malloc(sizeof(node));
newnode->data = d;
newnode->next = temp->next;
temp->next = newnode;
}
count++;
}
}
void display()
{
node *temp = head;
if(head==NULL)
{
printf("Empty List \n");
return;
}
while(temp->next != head)
{
printf("%d ",temp->data);
temp = temp->next;
}
printf("%d %d\n",temp->data,temp->next->data);
}
When the list is empty, i.e. head is NULL, your addnode doesn't create a circular list.
Your code will set newnode->next to NULL (because head is NULL) but what you want is newnode->next = newnode to get a circular list.
So inside addnode you need:
...
if(head==NULL)
{
head = newnode;
tail = newnode;
newnode->next = newnode;
}
...
Alternatively you can move the line newnode->next = head; to be after the if-else clause.