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  1.  
  2. #include <stdio.h>
  3. #include <stdlib.h>
  4. /* Basic node structure. */
  5. struct cl_node {
  6.     int INFO;
  7.     struct cl_node * NEXT;
  8. };
  9.  
  10. struct cl_node *FIRST = NULL;
  11. struct cl_node *LAST = NULL;
  12.  
  13. /* Functions declarations */
  14. void insert(int);
  15. void delete(int);
  16. void display(void);
  17. struct cl_node * search(int);
  18.  
  19. int main()
  20. {
  21.     int num1, num2, choice;
  22.  
  23.     struct cl_node *LOC = NULL;
  24.  
  25.     /* Run forever until user chooses 0 */
  26.     while(1)
  27.     {
  28. 	printf("--------------------------------------------\n");
  29. 	printf("        CIRCULAR LINKED LIST PROGRAM        \n");
  30. 	printf("--------------------------------------------\n");
  31. 	printf("1. Insert \n");
  32. 	printf("2. Delete \n");
  33. 	printf("3. Search\n");
  34. 	printf("4. Display\n");
  35. 	printf("*. Exit\n");
  36. 	printf("--------------------------------------------\n");
  37. 	printf("Enter your choice : ");
  38. 	scanf("%d", &choice);
  39. 	switch(choice)
  40. 	{
  41. 	    case 1:
  42. 		printf("Enter element to be inserted: ");
  43. 		scanf("%d", &num1);
  44. 		insert(num1);
  45. 		break;
  46. 	    case 2:
  47. 		printf("Enter key to delete from list: ");
  48. 		scanf("%d", &num2);
  49. 		delete(num2);
  50. 		break;
  51. 			case 3: printf("Enter key to be searched from list: ");
  52. 		scanf("%d", &num2);
  53. 		LOC=search(num2);
  54. 				if(LOC == NULL)
  55. 					printf("\nElement not found...!\n");
  56. 				else
  57. 					printf("\n Element found \n");
  58. 		break;
  59. 			case 4: display();
  60. 		break;
  61. 	    default: return 0;
  62. 	} // end case
  63.     } // end while
  64. }
  65.  
  66. void insert(int data)
  67. {
  68.   struct cl_node *PTR =
  69. 	      (struct cl_node*)malloc(sizeof(struct cl_node));
  70.     PTR->INFO = data;
  71. 	if(FIRST == NULL) // no CLL
  72. 	{
  73. 		FIRST = LAST = PTR;
  74. 		PTR->NEXT = FIRST;
  75. 	}
  76. 	else
  77. 	{
  78. 		LAST->NEXT = PTR;
  79. 		PTR->NEXT = FIRST;
  80. 		LAST = PTR;
  81. 	}
  82. }
  83.  
  84. void delete(int key)
  85. {
  86. 	struct cl_node *LOC, *TEMP;
  87. 	LOC = search(key);
  88. 	if (LOC == NULL)
  89. 	{
  90. 	  printf("\nElement not found...!\n");
  91.       return;
  92. 	}
  93. 	if(LOC==FIRST)
  94. 	{
  95. 		if(FIRST==LAST) // only element 
  96. 		{
  97. 			FIRST=LAST=NULL;
  98. 			free(LOC);
  99. 			return;
  100. 		}
  101. 		else
  102. 		{
  103. 			FIRST = FIRST->NEXT;
  104. 			LAST->NEXT = FIRST;
  105. 			free(LOC);
  106. 			return;
  107. 		}
  108. 	}
  109. 	for(TEMP=FIRST; TEMP->NEXT != LOC ; TEMP=TEMP->NEXT)
  110. 						;
  111. 	if(LOC == LAST)
  112. 	{
  113. 		LAST = TEMP;
  114. 		TEMP->NEXT = FIRST;
  115. 	}
  116. 	else
  117. 		TEMP->NEXT = LOC->NEXT;
  118. free(LOC);
  119.  return;
  120. }
  121.  
  122. struct cl_node * search(int key)
  123. {
  124.    struct cl_node *PTR;
  125.  
  126.    if(FIRST==NULL)
  127. 	   return NULL;
  128.    if(FIRST->INFO==key)
  129. 	 return FIRST;
  130.  
  131.    for(PTR=FIRST; PTR != LAST; PTR=PTR->NEXT)
  132. 	if(PTR->INFO == key)
  133. 	   return(PTR);
  134.    if(LAST->INFO == key)
  135. 	return(LAST);
  136.    else
  137. 	return(NULL);
  138. }
  139.  
  140. void display()
  141. {
  142. 	struct cl_node *PTR;
  143. 	if(FIRST==NULL) // no element
  144. 	{
  145. 	   printf("\n CIRCULAR Linked list is empty\n");
  146. 	   return;
  147. 	}
  148.  
  149. 	if(FIRST == LAST) // Single element
  150. 	{
  151. 		printf("\nFIRST --> %d --> LAST\n", FIRST->INFO);
  152. 		return;
  153. 	}
  154.  
  155. 	for (PTR=FIRST; PTR !=LAST; PTR=PTR->NEXT)
  156. 		printf("%d --> ", PTR->INFO) ;
  157.  
  158. 	printf("%d --> LAST\n",LAST->INFO);
  159. }
  160.  
Success #stdin #stdout 0s 5640KB
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--------------------------------------------
        CIRCULAR LINKED LIST PROGRAM        
--------------------------------------------
1. Insert 
2. Delete 
3. Search
4. Display
*. Exit
--------------------------------------------
Enter your choice :
https://ideone.com/GQMbE3
language:
C (gcc 8.3)
created:
2 years ago
visibility:
public

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