Insert a node after a given node in linked list

Article by: Manish Methani

Last Updated: October 11, 2021 at 10:04am IST
2 min 15 sec read

Linked List insertion can be done using three ways,

1) Insertion at front of given node.

2) Insertion after a given node.

3) Insertion at the end of node.

In this tutorial, we consider insertion at front of given node. To understand this look at the following figure,

1) Before Scenario : Insertion after a given node.

1) The original Linked list contains a head pointer pointing to the First Node.

2) First Node points to the second Node.

3) The second Node points to NULL.

2) After Scenario: Insertion after a given node.

Now if we want to insert a node after a given node of the linked list, it should be like,

1) Head is pointing to the first Node containing value 1.

2) New node next is Pointing to second Node containing value 3.

3) The first node points to the new node containing value 2.

4) The second node points to the third node containing value 4.

5) The third node containing value 4 points to null.

Playing with the linked list is a very easy task. Just you should know which node will points to which node. This was the beginning of linked list insertion.

Function to insert node after a given node of Linked List :

void insertAfter(struct node* prev_node, int dataValue)
{
  /*1. check if the given prev_node is NULL */
    if (prev_node == NULL) 
    { 
       printf("the given previous node cannot be NULL");       
       return;  
    }  
          
  /* 2. allocate new node */
    struct node* new_node =(struct node*) malloc(sizeof(struct node));
  
  /* 2. put data into new node */
    new_node->data  = dataValue;
  
    /* 4. Make next of new node as next of prev_node */
    new_node->next = prev_node->next; 
  
  /* 5. move the next of prev_node as new_node */
    prev_node->next = new_node;
}