Insertion in singly linked list (at the end).
There are two cases that need to be described in order to put a node at the end.
- The node is being added to a list that is currently empty.
- The node is appended to the connected list's end.
The first case:
- The condition (head == NULL) is satisfied in the first case. As a result, we only need to use the malloc statement in C to allocate space for the node. The following statements are used to build up the data and link parts of the node.
ptr->data = item;
ptr -> next = NULL;
- Because ptr is the only node that will be added into the list, it must be pointed to by the list's head pointer. The following statements will be used to do this.
Head = ptr
The second case:
- Because Head is not null, the condition Head = NULL would fail. In order to traverse the list, we must first declare a temporary pointer temp. temp is set to point to the list's initial node.
Temp = head
- Then, traverse through the entire linked list using the statements:
while (temp→ next != NULL)
temp = temp → next;
- The temp will point to the last node of the list at the end of the loop. Now, set aside space for the new node and assign the item to its data section.
- Because the new node will be the last node in the list, the next component of this node must point to null. The next section of the temp node (which is presently the list's last node) must point to the new node (ptr).
temp = head;
while (temp -> next != NULL)
{
temp = temp -> next;
}
temp->next = ptr;
ptr->next = NULL;
 |
| Insertion in singly linked list |
Algorithm
- Step 1: IF PTR = NULL Write OVERFLOW
[END OF IF]
- Step 2: SET NEW_NODE = PTR
- Step 3: SET PTR = PTR - > NEXT
- Step 4: SET NEW_NODE - > DATA = VAL
- Step 5: SET NEW_NODE - > NEXT = NULL
- Step 6: SET PTR = HEAD
- Step 7: Repeat Step 8 while PTR - > NEXT != NULL
- Step 8: SET PTR = PTR - > NEXT
- Step 9: SET PTR - > NEXT = NEW_NODE
- Step 10: EXIT
C program to insert data(at the end) in singly linked list.
#include<stdio.h>
#include<stdlib.h>
void lastinsert(int);
struct node
{
int data;
struct node *next;
};
struct node *head;
void main ()
{
int choice,item;
do
{
printf("\nEnter the item which you want to insert?\n");
scanf("%d",&item);
lastinsert(item);
printf("\nPress 0 to insert more ?\n");
scanf("%d",&choice);
}while(choice == 0);
}
void lastinsert(int item)
{
struct node *ptr = (struct node*)malloc(sizeof(struct node));
struct node *temp;
if(ptr == NULL)
{
printf("\nOVERFLOW");
}
else
{
ptr->data = item;
if(head == NULL)
{
ptr -> next = NULL;
head = ptr;
printf("\nNode inserted");
}
else
{
temp = head;
while (temp -> next != NULL)
{
temp = temp -> next;
}
temp->next = ptr;
ptr->next = NULL;
printf("\nNode inserted");
}
}
}
Expected Output:
Enter the item which you want to insert?
12
Node inserted
Press 0 to insert more ?
0
Enter the item which you want to insert?
23
Node inserted
Press 0 to insert more ?
2
