circular link list

//singly circular link list
#include<stdio.h>
#include<conio.h>
#include<stdlib.h>
struct sll
{
	int info;
	struct sll  *next;
}*temp=NULL,*next=NULL,*start=NULL,*prev=NULL,*node=NULL;
void create_node()
{
	node=(struct sll  *)malloc(sizeof(struct sll));
	if(node==NULL)
	{
		printf("\n NOde is not allocated\n");
		return;
	}
	printf("\n Enter the val: ");
	scanf("%d",&node->info);
	node->next=NULL;

}
void display()
{
	if(start==NULL)
	{
		printf("\n Csll is Empty");
		return;
	}
	printf("\n Displayed ");
	temp=start;
	if(start->next==start)
	{
		printf("\n %d",start->info);
		return;
	}

	printf("\n %d",start->info);
	temp=start->next;
	while(temp!=start)
	{
		printf("\n %d",temp->info);
		temp=temp->next;
	}
}
void insert_at_posi()
{
	int i,val,flag=0;

	printf("\n Enter the position:");
	scanf("%d",&val);
	//temp=start;
	if(val==1)
	{
		create_node();
		if(start==NULL)
		{
			node->next=node;
			start=node;
			display();
			return;
		}
		else
		{
			node->next=start;
			temp=start->next;
			while(temp->next!=start)
			{
				temp=temp->next;
			}
			temp->next=node;
			start=node;
			display();
			return;
		}
		//{






	}
	i=2;
	prev=start;
	temp=start->next;
	while(temp->next!=start)
	{
		if(i==val)
		{
			create_node();
			prev->next=node;
			node->next=temp;
			flag=1;
			display();
			break;
		}
		prev=temp;

		i++;

		temp=temp->next;
	}
	if(flag==0)
	{
		printf("\n Invalid possition ");
	}
}
void revers()
{
	if(start==NULL || start->next==start)
	{
		display();
		return;
	}
	prev=start;
	temp=start->next;
	while(temp->next!=start)
	{

		next=temp->next;
		temp->next=prev;
		prev=temp;
		temp=next;


	}
	start->next=temp;
	temp->next=prev;
	start=temp;
	display();
}
void del()
{
	if(start==NULL)
	{
		display();
		return;
	}
	if(start->next==start)
	{
		printf("\n %d is deleted ",start->info);
		free(start);
		start=NULL;
		display();
		return;
	}
	prev=start;
	temp=start->next;
	while(temp->next!=start)
	{
		prev=temp;
		temp=temp->next;
	}
	prev->next=temp->next;
	printf("\n %d is deleted",temp->info);
	free(temp);
	display();

}
int main()
{
	int ch;
	clrscr();
	do
	{
		printf("\n Menu");
		printf("\n 1. Insert at posi");
		printf("\n 2. Delete at end");
		printf("\n 3. Revers the list");
		printf("\n 4. display");
		printf("\n Enter your choice: ");
		scanf("%d",&ch);
		switch(ch)
		{
			case 1:
				insert_at_posi();
			break;

			case 2:
				del();
			break;

			case 3:
				revers();

			break;

			case 4:
				display();
			break;
		}
	}while(ch>=1 && ch<=4);
	getch();
	return 0;
}