CodeTheta

/* create circular header linked list by using function */
/* circheaderlst.C */
/* http://native-code.blogspot.com */

# include <stdio.h>
# include <malloc.h>

struct link
{
    int info;
    struct link *next;
};

int i; /* Represents number of nodes in the list */
int number;
struct link *start, *new1;

void insertion(struct link *);
void create_circular_list(struct link *);
void display(struct link *);


/* Function create a circular header linked list */
/* http://native-code.blogspot.com */

void create_circular_list( struct link *node)
{
    char ch;

    node = start;      /* Point to the header node in the list */
    node->next = (struct link *) malloc(sizeof(struct link));
    i = 0;
    printf("\n Input choice n for break: ");
    ch = getchar();
    while(ch != 'n')
    {
        node->next = (struct link* ) malloc(sizeof(struct link));
        node = node->next;
        printf("\n Input the node: %d:", (i+1));
        scanf("%d", &node->info);
        fflush(stdin);
        printf("\n Input choice n for break: ");
        ch = getchar();
        i++;
    }
    printf("\n Total nodes = %d", i);
    node = start;
    node->info = i; /* Assign total number of nodes to the header node */
}

/* Inserting a node in circular header linked */
/* http://native-code.blogspot.com */

void insertion(struct link *node)
{
    int count = node->info;
    int node_number = 0;
    int insert_node;

    node = start;
    node = node->next;

    printf("\n Input node number you want to insert: ");
    printf("\n Value should be less are equal to the");
    printf("\n number of nodes in the list: ");
    scanf("%d", &insert_node);

    while(count)
    {
        if((node_number+1) == insert_node)
        {
            new1 = (struct link* ) malloc(sizeof(struct link));
            new1->next = node->next ;
            node->next = new1;
            printf("\n Input the node value: ");
            scanf("%d", &new1->info);
            node = node->next;
            count--;
        }
        else
        {
            node = node->next;
            count--;
        }
        node_number ++;
    }
    if (count == 0)
    {
        node = start;  /* Points to header node */
        node->info = node->info+1;
    }
}

/* Display the list */
/* http://native-code.blogspot.com */

void display(struct link *node)
{
    int count = node->info;

    node = start;
    node = node->next;

    while (count-1)
    {
        printf("\n 0x%x", node);
        printf(" %d ", node->info);
        node = node->next;
        count --;
    }
}

/* Function main */
/* http://native-code.blogspot.com */

void main()
{
    struct link *node = (struct link *) malloc(sizeof(struct link));
    create_circular_list(node);
    printf("\n Before inserting a node list is as follows:\n");
    display(node);
    insertion(node);
    printf("\n After inserting a node list is as follows:\n");
    display(node);
}
/* http://native-code.blogspot.com */