Deletion in /doubly Linked List

Author: sudesh1611

Data Structures/DoublyLinkedList/Deletion.c

@@ -0,0 +1,101 @@
+
+#include <stdio.h> 
+#include <stdlib.h> 
+  
+/* a node of the doubly linked list */
+struct Node 
+{ 
+  int data; 
+  struct Node *next; 
+  struct Node *prev; 
+}; 
+  
+/* Function to delete a node in a Doubly Linked List. 
+   head_ref --> pointer to head node pointer. 
+   del  -->  pointer to node to be deleted. */
+void deleteNode(struct Node **head_ref, struct Node *del) 
+{ 
+  /* base case */
+  if(*head_ref == NULL || del == NULL) 
+    return; 
+  
+  /* If node to be deleted is head node */
+  if(*head_ref == del) 
+    *head_ref = del->next; 
+  
+  /* Change next only if node to be deleted is NOT the last node */
+  if(del->next != NULL) 
+    del->next->prev = del->prev; 
+  
+  /* Change prev only if node to be deleted is NOT the first node */
+  if(del->prev != NULL) 
+    del->prev->next = del->next;      
+  
+  /* Finally, free the memory occupied by del*/
+  free(del); 
+  return; 
+}      
+  
+/* UTILITY FUNCTIONS */
+/* Function to insert a node at the beginning of the Doubly Linked List */
+void push(struct Node** head_ref, int new_data) 
+{ 
+  /* allocate node */
+  struct Node* new_node = 
+       (struct Node*) malloc(sizeof(struct Node)); 
+  
+  /* put in the data  */
+  new_node->data  = new_data; 
+  
+  /* since we are adding at the begining, 
+    prev is always NULL */
+  new_node->prev = NULL; 
+  
+  /* link the old list off the new node */
+  new_node->next = (*head_ref);     
+  
+  /* change prev of head node to new node */
+  if((*head_ref) !=  NULL) 
+   (*head_ref)->prev = new_node ;     
+  
+  /* move the head to point to the new node */
+   (*head_ref)    = new_node; 
+} 
+  
+/* Function to print nodes in a given doubly linked list 
+   This function is same as printList() of singly linked lsit */
+void printList(struct Node *node) 
+{ 
+  while(node!=NULL) 
+  { 
+   printf("%d ", node->data); 
+   node = node->next; 
+  } 
+} 
+  
+/* Drier program to test above functions*/
+int main() 
+{ 
+  /* Start with the empty list */
+  struct Node* head = NULL; 
+  
+  /* Let us create the doubly linked list 10<->8<->4<->2 */
+  push(&head, 2); 
+  push(&head, 4); 
+  push(&head, 8); 
+  push(&head, 10); 
+  
+  printf("\n Original Linked list "); 
+  printList(head); 
+  
+  /* delete nodes from the doubly linked list */
+  deleteNode(&head, head);  /*delete first node*/
+  deleteNode(&head, head->next);  /*delete middle node*/
+  deleteNode(&head, head->next);  /*delete last node*/
+  
+  /* Modified linked list will be NULL<-8->NULL */
+  printf("\n Modified Linked list "); 
+  printList(head);            
+  
+  getchar(); 
+}