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  1.  
  2. #include <stdio.h>
  3. #include <stdlib.h>
  4. #include <string.h>
  5.  
  6. struct Node {
  7.     char *data;
  8.     struct Node *prev;
  9.     struct Node *next;
  10. };
  11.  
  12. // Create node
  13. struct Node* createNode(const char *data) {
  14.     struct Node *newNode = (struct Node*)malloc(sizeof(struct Node));
  15.     if (!newNode) return NULL;
  16.  
  17.     newNode->data = (char*)malloc(10);
  18.     strncpy(newNode->data, data, 9);
  19.     newNode->data[9] = '\0';
  20.  
  21.     newNode->prev = NULL;
  22.     newNode->next = NULL;
  23.  
  24.     return newNode;
  25. }
  26.  
  27. // Insert at end (helper)
  28. void insertEnd(struct Node **head, const char *data) {
  29.     struct Node *newNode = createNode(data);
  30.  
  31.     if (*head == NULL) {
  32.         *head = newNode;
  33.         return;
  34.     }
  35.  
  36.     struct Node *temp = *head;
  37.     while (temp->next)
  38.         temp = temp->next;
  39.  
  40.     temp->next = newNode;
  41.     newNode->prev = temp;
  42. }
  43.  
  44. // Insert after a given value
  45. void insertAfter(struct Node **head, const char *target, const char *data) {
  46.     struct Node *temp = *head;
  47.  
  48.     while (temp && strcmp(temp->data, target) != 0)
  49.         temp = temp->next;
  50.  
  51.     if (!temp) return;
  52.  
  53.     struct Node *newNode = createNode(data);
  54.  
  55.     newNode->next = temp->next;
  56.     newNode->prev = temp;
  57.  
  58.     if (temp->next)
  59.         temp->next->prev = newNode;
  60.  
  61.     temp->next = newNode;
  62. }
  63.  
  64. // Insert before a given value
  65. void insertBefore(struct Node **head, const char *target, const char *data) {
  66.     struct Node *temp = *head;
  67.  
  68.     while (temp && strcmp(temp->data, target) != 0)
  69.         temp = temp->next;
  70.  
  71.     if (!temp) return;
  72.  
  73.     struct Node *newNode = createNode(data);
  74.  
  75.     newNode->next = temp;
  76.     newNode->prev = temp->prev;
  77.  
  78.     if (temp->prev)
  79.         temp->prev->next = newNode;
  80.     else
  81.         *head = newNode;   // updating head
  82.  
  83.     temp->prev = newNode;
  84. }
  85.  
  86. // Delete node by value
  87. void deleteNode(struct Node **head, const char *target) {
  88.     struct Node *temp = *head;
  89.  
  90.     while (temp && strcmp(temp->data, target) != 0)
  91.         temp = temp->next;
  92.  
  93.     if (!temp) return;
  94.  
  95.     if (temp->prev)
  96.         temp->prev->next = temp->next;
  97.     else
  98.         *head = temp->next;
  99.  
  100.     if (temp->next)
  101.         temp->next->prev = temp->prev;
  102.  
  103.     free(temp->data);
  104.     free(temp);
  105. }
  106.  
  107. // Reverse DLL
  108. void reverse(struct Node **head) {
  109.     struct Node *temp = NULL;
  110.     struct Node *current = *head;
  111.  
  112.     while (current) {
  113.         temp = current->prev;
  114.         current->prev = current->next;
  115.         current->next = temp;
  116.         current = current->prev;
  117.     }
  118.  
  119.     if (temp)
  120.         *head = temp->prev;
  121. }
  122.  
  123. // Print list
  124. void printList(struct Node *head) {
  125.     printf("List: ");
  126.     while (head) {
  127.         printf("%s <-> ", head->data);
  128.         head = head->next;
  129.     }
  130.     printf("NULL\n");
  131. }
  132.  
  133. // Free memory
  134. void freeList(struct Node **head) {
  135.     struct Node *temp;
  136.  
  137.     while (*head) {
  138.         temp = *head;
  139.         *head = (*head)->next;
  140.         free(temp->data);
  141.         free(temp);
  142.     }
  143. }
  144.  
  145. int main() {
  146.     struct Node *head = NULL;
  147.  
  148.     printf("==== CREATE LIST ====\n");
  149.     insertEnd(&head, "A");
  150.     insertEnd(&head, "B");
  151.     insertEnd(&head, "C");
  152.     printList(head);
  153.  
  154.     printf("\n==== INSERT AFTER B ====\n");
  155.     insertAfter(&head, "B", "X");
  156.     printList(head);
  157.  
  158.     printf("\n==== INSERT BEFORE B ====\n");
  159.     insertBefore(&head, "B", "Y");
  160.     printList(head);
  161.  
  162.     printf("\n==== DELETE NODE B ====\n");
  163.     deleteNode(&head, "B");
  164.     printList(head);
  165.  
  166.     printf("\n==== INSERT AT HEAD (before A) ====\n");
  167.     insertBefore(&head, "A", "HEAD");
  168.     printList(head);
  169.  
  170.     printf("\n==== REVERSE LIST ====\n");
  171.     reverse(&head);
  172.     printList(head);
  173.  
  174.     printf("\n==== CLEANUP ====\n");
  175.     freeList(&head);
  176.  
  177.     return 0;
  178. }
Success #stdin #stdout 0s 5320KB
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stdin
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Standard input is empty
stdout
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==== CREATE LIST ====
List: A <-> B <-> C <-> NULL

==== INSERT AFTER B ====
List: A <-> B <-> X <-> C <-> NULL

==== INSERT BEFORE B ====
List: A <-> Y <-> B <-> X <-> C <-> NULL

==== DELETE NODE B ====
List: A <-> Y <-> X <-> C <-> NULL

==== INSERT AT HEAD (before A) ====
List: HEAD <-> A <-> Y <-> X <-> C <-> NULL

==== REVERSE LIST ====
List: C <-> X <-> Y <-> A <-> HEAD <-> NULL

==== CLEANUP ====
https://ideone.com/k82OYU
language:
C (gcc 8.3)
created:
1 day ago
visibility:
public

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