Singly Linked List: Insert at Front

Singly Linked List Insert at Front

#include<stdio.h>

#include<malloc.h>

#include<stdlib.h>

struct node

{

            int data;

            struct node *link;

};

typedef struct node * NODE;

NODE insert_at_front(NODE first, int item);

void display(NODE first);

NODE getnode()

{

            NODE x;

            x = (NODE)malloc(sizeof(struct node));

            x->link = NULL;

            return x;

}

NODE insert_at_front(NODE first, int item)

{

            NODE temp;

            temp = getnode();

            temp->data = item;

            /*Case 1: List is empty.*/

            if(first==NULL)

                        return temp;

            /*Case 2: List has nodes. Insert temp node in the front*/

            temp->link = first;

            return temp;

           

                                    /*

                                                            ( or )

                                                    if(first)

                                                                    temp->link = first;

                                                    return temp;

                                     */

}

void display(NODE first)

{

            NODE cur;

            cur = first;

            printf("\nContents are:");

            if(cur == NULL)

                        printf("\nList is empty. Nothing to display.");

            else

            {

                        while(cur!=NULL)

                        {

                                    printf("%d  ", cur->data);

                                    cur = cur->link;

                        }

            }

}

void main()

{

            int ch, item;

            NODE first = NULL;

            while(1)

            {

                        printf("\n\n~~MENU~~");

                        printf("\n1.Insert at front");

                        printf("\n2.Display");

                        printf("\n3.exit");

                        printf("\nEnter your choice: ");

                        scanf("%d",&ch);

                        switch(ch)

                        {

                                    case 1:             printf("\nEnter the value: ");

                                                            scanf("%d", &item);

                                                            first = insert_at_front(first, item);

                                                            break;

                                    case 2:            display(first);

                                                            break;

                                    case 3:  exit(0);

                        }

            }

}

Output:

~~MENU~~

1.Insert at front

2.Display

3.exit

Enter your choice: 1

Enter the value: 11

~~MENU~~

1.Insert at front

2.Display

3.exit

Enter your choice: 1

Enter the value: 12

~~MENU~~

1.Insert at front

2.Display

3.exit

Enter your choice: 2

Contents are: 12      11

~~MENU~~

1.Insert at front

2.Display

3.exit

Enter your choice: 3



Also Check,

• Singly Linked List
• Insert at Front
• Insert at End
• Delete from Front
• Delete from End
• Insert and Delete operations