DS9.C

#include <stdio.h>
#include <stdlib.h>
 
struct node
{
    int data;
    struct node *link;
};
 
struct node *head = NULL, *x, *y, *z;
 
//void create();
void ins_at_beg();
void ins_at_pos();
void del_at_beg();
void del_at_pos();
void traverse();


void main()
{
    int ch;


    while (1)
    {clrscr();
    printf(" \n1.Insertion at beginning \n2.Insertion at position");
    printf("\n3Deletion at beginning \n4.Deletion at position \n5.Traverse");
    printf("\n6.Exit\n");
	printf("\n Enter your choice:");
	scanf("%d", &ch);
	switch(ch)
	{
	case 1:
	    ins_at_beg();
	    break;
	case 2:
	    ins_at_pos();
	    break;
	case 3:
	    del_at_beg();
	    break;
	case 4:
	    del_at_pos();
	    break;
	case 5:
	    traverse();
	    break;
	default:
	    exit(0);
	}
    }
}

/*Function to create a new circular linked list
void create()
{
    int c;

    x = (struct node*)malloc(sizeof(struct node));
    printf("\n Enter the data:");
    scanf("%d", &x->data);
    x->link = x;
    head = x;
    printf("\n If you wish to continue press 1 otherwise 0:");
    scanf("%d", &c);
    while (c != 0)
    {
	y = (struct node*)malloc(sizeof(struct node));
	printf("\n Enter the data:");
	scanf("%d", &y->data);
	x->link = y;
	y->link = head;
	x = y;
	printf("\n If you wish to continue press 1 otherwise 0:");
	scanf("%d", &c);
    }
}        */


/*Function to insert an element at the begining of the list*/

void ins_at_beg()
{
    x = head;
    y = (struct node*)malloc(sizeof(struct node));
    printf("\n Enter the data:");
    scanf("%d", &y->data);
    while (x->link != head)
    {
	x = x->link;
    }
    x->link = y;
    y->link = head;
    head = y;
}

/*Function to insert an element at any position the list*/

void ins_at_pos()
{
    struct node *ptr;
    int c = 1, pos, count = 1;

    y = (struct node*)malloc(sizeof(struct node));
    if (head == NULL)
    {
	printf("cannot enter an element at this place");
    }
    printf("\n Enter the data:");
    scanf("%d", &y->data);
    printf("\n Enter the position to be inserted:");
    scanf("%d", &pos);
    x = head;
    ptr = head;
    while (ptr->link != head)
    {
	count++;
	ptr = ptr->link;
    }
    count++;
    if (pos > count)
    {
	printf("OUT OF BOUND");
	return;
    }
    while (c < pos)
    {
	z = x;
	x = x->link;
	c++;
    }
    y->link = x;
    z->link = y;
}

/*Function to delete an element at any begining of the list*/

void del_at_beg()
{
    if (head == NULL)
	printf("\n List is empty");
    else
    {
	x = head;
	y = head;
	while (x->link !=  head)
	{
	    x = x->link;
	}
	head = y->link;
	x->link = head;
	free(y);
    }
}

/*Function to delete an element at any position the list*/

void del_at_pos()
{
    if (head == NULL)
	printf("\n List is empty");
    else
    {
	int c = 1, pos;
	printf("\n Enter the position to be deleted:");
	scanf("%d", &pos);
	x = head;
	while (c < pos)
	{
	    y = x;
	    x = x->link;
	    c++;
	}
	y->link = x->link;
free(x);
    }
}

/*Function to display the elements in the list*/

void traverse()
{
    if (head == NULL)
	printf("\n List is empty");
    else
    {
	x = head;
	while (x->link !=  head)
	{
	    printf("%d \t", x->data);
	    x = x->link;
	}
       //	printf("%d", x->data);
    }getch();
}