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1 file changed, 338 insertions

6.c(file created)

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1 + /*
2 + * Ex. No. 6: IMPLEMENTATION OF DOUBLY LINKED LIST
3 + * Library Borrowed Book Record System using a doubly linked list
4 + * Supports: INSERT (beginning/end/position), DELETE (beginning/end/position/by ID),
5 + * SEARCH by Book ID, DISPLAY (forward/reverse)
6 + */
7 + #include <stdio.h>
8 + #include <stdlib.h>
9 + #include <string.h>
10 +
11 + #define TITLE_LEN 60
12 + #define AUTHOR_LEN 50
13 +
14 + struct Node {
15 + int bookId;
16 + char title[TITLE_LEN];
17 + char author[AUTHOR_LEN];
18 + struct Node *prev;
19 + struct Node *next;
20 + };
21 +
22 + struct Node *head = NULL;
23 +
24 + /* Count nodes in list */
25 + int countNodes(void) {
26 + int count = 0;
27 + struct Node *cur = head;
28 + while (cur != NULL) {
29 + count++;
30 + cur = cur->next;
31 + }
32 + return count;
33 + }
34 +
35 + /* Return the last node, or NULL if the list is empty */
36 + struct Node *lastNode(void) {
37 + struct Node *cur = head;
38 + if (cur == NULL) {
39 + return NULL;
40 + }
41 + while (cur->next != NULL) {
42 + cur = cur->next;
43 + }
44 + return cur;
45 + }
46 +
47 + struct Node *makeNode(int bookId, const char *title, const char *author) {
48 + struct Node *node = (struct Node *)malloc(sizeof(struct Node));
49 + if (node == NULL) {
50 + printf("Memory allocation failed.\n");
51 + exit(1);
52 + }
53 + node->bookId = bookId;
54 + strcpy(node->title, title);
55 + strcpy(node->author, author);
56 + node->prev = NULL;
57 + node->next = NULL;
58 + return node;
59 + }
60 +
61 + /* i) Insert at beginning */
62 + void insertBeginning(int bookId, const char *title, const char *author) {
63 + struct Node *node = makeNode(bookId, title, author);
64 + node->next = head;
65 + if (head != NULL) {
66 + head->prev = node;
67 + }
68 + head = node;
69 + printf("Record inserted at beginning.\n");
70 + }
71 +
72 + /* ii) Insert at end */
73 + void insertEnd(int bookId, const char *title, const char *author) {
74 + struct Node *node = makeNode(bookId, title, author);
75 + struct Node *last = lastNode();
76 + if (last == NULL) {
77 + head = node;
78 + } else {
79 + last->next = node;
80 + node->prev = last;
81 + }
82 + printf("Record inserted at end.\n");
83 + }
84 +
85 + /* iii) Insert at a given position (1-based) */
86 + void insertAtPosition(int pos, int bookId, const char *title, const char *author) {
87 + int size = countNodes();
88 + if (pos < 1 || pos > size + 1) {
89 + printf("Invalid position. Valid range is 1 to %d.\n", size + 1);
90 + return;
91 + }
92 + if (pos == 1) {
93 + insertBeginning(bookId, title, author);
94 + return;
95 + }
96 +
97 + struct Node *prev = head;
98 + int i;
99 + for (i = 1; i < pos - 1; i++) {
100 + prev = prev->next;
101 + }
102 +
103 + struct Node *node = makeNode(bookId, title, author);
104 + node->next = prev->next;
105 + node->prev = prev;
106 + if (prev->next != NULL) {
107 + prev->next->prev = node;
108 + }
109 + prev->next = node;
110 + printf("Record inserted at position %d.\n", pos);
111 + }
112 +
113 + /* iv) Delete from beginning */
114 + void deleteBeginning(void) {
115 + if (head == NULL) {
116 + printf("List is empty. Nothing to delete.\n");
117 + return;
118 + }
119 + struct Node *doomed = head;
120 + head = head->next;
121 + if (head != NULL) {
122 + head->prev = NULL;
123 + }
124 + printf("Deleted record: BookID=%d, Title=%s\n", doomed->bookId, doomed->title);
125 + free(doomed);
126 + }
127 +
128 + /* v) Delete from end */
129 + void deleteEnd(void) {
130 + if (head == NULL) {
131 + printf("List is empty. Nothing to delete.\n");
132 + return;
133 + }
134 + struct Node *doomed = lastNode();
135 + if (doomed->prev == NULL) {
136 + head = NULL;
137 + } else {
138 + doomed->prev->next = NULL;
139 + }
140 + printf("Deleted record: BookID=%d, Title=%s\n", doomed->bookId, doomed->title);
141 + free(doomed);
142 + }
143 +
144 + /* vi) Delete from a given position (1-based) */
145 + void deleteAtPosition(int pos) {
146 + int size = countNodes();
147 + if (head == NULL) {
148 + printf("List is empty. Nothing to delete.\n");
149 + return;
150 + }
151 + if (pos < 1 || pos > size) {
152 + printf("Invalid position. Valid range is 1 to %d.\n", size);
153 + return;
154 + }
155 + if (pos == 1) {
156 + deleteBeginning();
157 + return;
158 + }
159 +
160 + struct Node *doomed = head;
161 + int i;
162 + for (i = 1; i < pos; i++) {
163 + doomed = doomed->next;
164 + }
165 +
166 + doomed->prev->next = doomed->next;
167 + if (doomed->next != NULL) {
168 + doomed->next->prev = doomed->prev;
169 + }
170 + printf("Deleted record: BookID=%d, Title=%s\n", doomed->bookId, doomed->title);
171 + free(doomed);
172 + }
173 +
174 + /* vii) Delete a record by its Book ID */
175 + void deleteById(int bookId) {
176 + struct Node *cur = head;
177 + while (cur != NULL && cur->bookId != bookId) {
178 + cur = cur->next;
179 + }
180 + if (cur == NULL) {
181 + printf("Book ID %d not found.\n", bookId);
182 + return;
183 + }
184 +
185 + if (cur->prev == NULL) {
186 + head = cur->next;
187 + } else {
188 + cur->prev->next = cur->next;
189 + }
190 + if (cur->next != NULL) {
191 + cur->next->prev = cur->prev;
192 + }
193 + printf("Deleted record: BookID=%d, Title=%s\n", cur->bookId, cur->title);
194 + free(cur);
195 + }
196 +
197 + /* viii) Search by Book ID */
198 + void search(int bookId) {
199 + struct Node *cur = head;
200 + int pos = 1;
201 + while (cur != NULL) {
202 + if (cur->bookId == bookId) {
203 + printf("Found at position %d: BookID=%d, Title=%s, Author=%s\n",
204 + pos, cur->bookId, cur->title, cur->author);
205 + return;
206 + }
207 + cur = cur->next;
208 + pos++;
209 + }
210 + printf("Book ID %d not found.\n", bookId);
211 + }
212 +
213 + /* ix) Display all records in forward order */
214 + void displayForward(void) {
215 + if (head == NULL) {
216 + printf("List is empty.\n");
217 + return;
218 + }
219 + struct Node *cur = head;
220 + int pos = 1;
221 + printf("--- Borrowed Book Records (Forward) ---\n");
222 + while (cur != NULL) {
223 + printf("%d) BookID=%d, Title=%s, Author=%s\n", pos, cur->bookId, cur->title, cur->author);
224 + cur = cur->next;
225 + pos++;
226 + }
227 + }
228 +
229 + /* x) Display all records in reverse order */
230 + void displayReverse(void) {
231 + if (head == NULL) {
232 + printf("List is empty.\n");
233 + return;
234 + }
235 + struct Node *cur = lastNode();
236 + int pos = countNodes();
237 + printf("--- Borrowed Book Records (Reverse) ---\n");
238 + while (cur != NULL) {
239 + printf("%d) BookID=%d, Title=%s, Author=%s\n", pos, cur->bookId, cur->title, cur->author);
240 + cur = cur->prev;
241 + pos--;
242 + }
243 + }
244 +
245 + /* Free all remaining nodes before exit */
246 + void freeList(void) {
247 + struct Node *cur = head;
248 + while (cur != NULL) {
249 + struct Node *next = cur->next;
250 + free(cur);
251 + cur = next;
252 + }
253 + head = NULL;
254 + }
255 +
256 + void readBook(int *bookId, char *title, char *author) {
257 + printf("Enter book ID: ");
258 + scanf("%d", bookId);
259 + printf("Enter book title: ");
260 + scanf(" %59[^\n]", title);
261 + printf("Enter author name: ");
262 + scanf(" %49[^\n]", author);
263 + }
264 +
265 + int main(void) {
266 + int choice, bookId, pos;
267 + char title[TITLE_LEN];
268 + char author[AUTHOR_LEN];
269 +
270 + do {
271 + printf("\n===== Library Borrowed Book Record System =====\n");
272 + printf("1. Insert at Beginning\n");
273 + printf("2. Insert at End\n");
274 + printf("3. Insert at a Given Position\n");
275 + printf("4. Delete from Beginning\n");
276 + printf("5. Delete from End\n");
277 + printf("6. Delete from a Given Position\n");
278 + printf("7. Delete by Book ID\n");
279 + printf("8. Search by Book ID\n");
280 + printf("9. Display Forward\n");
281 + printf("10. Display Reverse\n");
282 + printf("11. Exit\n");
283 + printf("Enter your choice: ");
284 + scanf("%d", &choice);
285 +
286 + switch (choice) {
287 + case 1:
288 + readBook(&bookId, title, author);
289 + insertBeginning(bookId, title, author);
290 + break;
291 + case 2:
292 + readBook(&bookId, title, author);
293 + insertEnd(bookId, title, author);
294 + break;
295 + case 3:
296 + printf("Enter position: ");
297 + scanf("%d", &pos);
298 + readBook(&bookId, title, author);
299 + insertAtPosition(pos, bookId, title, author);
300 + break;
301 + case 4:
302 + deleteBeginning();
303 + break;
304 + case 5:
305 + deleteEnd();
306 + break;
307 + case 6:
308 + printf("Enter position: ");
309 + scanf("%d", &pos);
310 + deleteAtPosition(pos);
311 + break;
312 + case 7:
313 + printf("Enter book ID to delete: ");
314 + scanf("%d", &bookId);
315 + deleteById(bookId);
316 + break;
317 + case 8:
318 + printf("Enter book ID to search: ");
319 + scanf("%d", &bookId);
320 + search(bookId);
321 + break;
322 + case 9:
323 + displayForward();
324 + break;
325 + case 10:
326 + displayReverse();
327 + break;
328 + case 11:
329 + printf("Exiting...\n");
330 + break;
331 + default:
332 + printf("Invalid choice.\n");
333 + }
334 + } while (choice != 11);
335 +
336 + freeList();
337 + return 0;
338 + }
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