DS | Practical - 9 | C Program to Perform Operations on The Doubly Linked List

 

Write a C Program to Perform Operations on The Doubly Linked List

GTU DS Practical-9

Write a program to implement the following operations on the doubly linked list.
(a) Insert a node at the front of the linked list.
(b) Insert a node at the end of the linked list.
(c) Delete a last node of the linked list.
(d) Delete a node before a specified position.

Code for Doubly Linked List

1. #include<stdio.h>
2. #include<stdlib.h>
3. struct node
4. {
5. int info;
6. struct node *lptr,*rptr;
7. }*l,*r;
8. void doubins(int);
9. void doubdel(int);
10. void display();
11. int chk;
12. void main()
13. {
14. int ch,x;
15. l=NULL;
16. r=NULL;
17. do
18. {
19. printf("\n Press:=>\n");
20. printf("\n 1.Insert Node");
21. printf("\n 2.Delete Node");
22. printf("\n 3.Display Doubly Linked List");
23. printf("\n 4.Exit");
24. printf("\n Enter Choice: ");
25. scanf("%d",&ch);
26. switch(ch)
27. {
28. case 1:
29. printf("\n\t Enter Element: ");
30. scanf("%d",&x);
31. doubins(x);
32. display();
33. break;
34. case 2:
35. printf("\n\t Enter Element which you want to Delete: ");
36. scanf("%d",&x);
37. chk=0;
38. if(l!=NULL) //if(r!=NULL)
39. {
40. printf("\n\n Before Deletion:=>");
41. printf("\n----------------");
42. display();
43. }
44. doubdel(x);
45. if(chk==0) //if(r!=NULL)
46. {
47. printf("\n\n\n\n\n After Deletion:=>");
48. printf("\n---------------");
49. display();
50. }
51. break;
52. case 3:
53. display();
54. break;
55. case 4:
56. exit(0);
57. default:
58. printf("\n\t Invalid Choice.\n\tTry Again.");
59. }
60. }while(ch!=4);
61. }
62. void doubins(int x)
63. {
64. struct node *New,*temp;
65. New=(struct node *)malloc(sizeof(struct node));
66. New->info=x;
67. if(l==NULL) //if(r==NULL)
68. {
69. New->lptr=NULL;
70. New->rptr=NULL;
71. l=New;
72. r=New;
73. return;
74. }
75. if(x<=l->info) //If the Node is less than all the Nodes
76. {
77. New->lptr=NULL;
78. New->rptr=l;
79. l->lptr=New;
80. l=New;
81. return;
82. }
83. temp=l; //If the Node is inserted in between two nodes
84. while(temp->info<x && temp!=NULL)
85. temp=temp->rptr;
86. if(temp!=NULL)
87. {
88. New->lptr=temp->lptr;
89. New->rptr=temp;
90. temp->lptr=New;
91. New->lptr->rptr=New;
92. return;
93. }
94. New->rptr=NULL; //Node is inserted at last
95. New->lptr=r;
96. r->rptr=New;
97. r=New;
98. }
100. void doubdel(int x)
101. {
102. struct node *temp;
103. if(l==NULL) //if(r==NULL)
104. {
105. printf("\n\n\tDoubly Linked List Underflow on Delete.");
106. chk=1;
107. return;
108. }
109. if(x==l->info) //If First Node is tobe Deleted
110. {
111. temp=l;
112. l=l->rptr;
113. l->lptr=NULL;
114. free(temp);
115. return;
116. }
117. if(x==r->info) //If Last Node is tobe Deleted
118. {
119. temp=r;
120. r=r->lptr;
121. r->rptr=NULL;
122. free(temp);
123. return;
124. }
125. temp=l;
126. while(temp->info!=x && temp!=NULL)
127. temp=temp->rptr;
128. if(temp==NULL) //If Node not found in the List
129. {
130. /* gotoxy(1,13);
131. delline();
132. gotoxy(1,13);
133. delline();
134. gotoxy(1,14);
135. delline();
136. gotoxy(1,16);
137. delline();
138. gotoxy(1,17);
139. delline();
140. gotoxy(1,18);
141. delline();
142. gotoxy(10,13);
143. printf("\n\tNode not found.");
144. chk=1;
145. return; */
146. }
147. temp->lptr->rptr=temp->rptr;
148. temp->rptr->lptr=temp->lptr;
149. free(temp);
150. return;
151. }
153. void display()
154. {
155. struct node *temp;
156. if(l==NULL) //if(r==NULL)
157. printf("\n\n\tDoubly Linked List is Empty.");
158. else
159. {
160. printf("\n\nDoubly Linked List:\n\n\n");
161. printf("l = %u\n\n",l);
162. temp=l;
163. while(temp!=NULL)
164. {
165. printf("[%u|%u|%d|%u]->",temp,temp->lptr,temp->info,temp->rptr);
166. temp=temp->rptr;
167. }
168. printf("NULL");
169. printf("\n\nr = %u",r);
170. }
171. }

 

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