Friday, 5 July 2013

THIS PROGRAM INSERTS A NODE AT THE BEGINNING OF SIMPLE LINKED LIST



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

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

int i;
int num;
struct list start, *prev, *new1;

void insert_first(struct list *);
void create_list(struct list *);
void display(struct list *);

/* Function to create linked list */

 void create_list(struct list *ptr)
 {
    int n;
    ptr = &start;      /* Ptr points to the start pointer */
    printf("\n How many nodes you want to create: ");
    scanf("%d",&n);
    i=0;
    printf("\n\n ==============================================================================\n");
    printf("\n Note That:\n -----------\n Enter numeric data in node\n");
    printf("\n ==============================================================================\n");
    while( i!=n)
    {
        ptr->link = (struct list *) malloc(sizeof(struct list));
        ptr = ptr->link;
        printf("\n Enter the values of the node : %d: ", (i+1));
        scanf("%d", &ptr->info);
        ptr->link = NULL;
        i++;
    }
    printf("\n\n ---------------");
    printf("\n Total nodes = %d",i);
    printf("\n ---------------\n\n");
}

/* Function to display the list */

void display(struct list *ptr)
{
    ptr = start.link;
    while (ptr)
    {
        printf("\n\n\t\t%d", ptr->info);
        ptr = ptr->link;
    }
}

/* Function to insert node at beginning */

void insert_first(struct list *ptr)
{
    ptr = start.link;
    prev = &start;
    new1 = (struct list* ) malloc(sizeof(struct list));
    new1->link = ptr ;
    prev->link = new1;
    printf("\n\n --------------------------------------");
    printf("\n Enter the item you want to insert: ");
    scanf("%d",&new1->info);

}

/* Main Function */

void main()
{

    struct list *ptr = (struct list *) malloc(sizeof(struct list));
    clrscr();
    create_list(ptr);
    printf("\n Linked list is: ");
    printf("\n ----------------------\n");
    display(ptr);
    insert_first (ptr);
    printf("\n ------------------------------------------\n");
    printf("\n Linked list after insertion of first node: \n");
    printf("\n ------------------------------------------\n");
    display(ptr);
    getch();

}

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