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  1. #include <iostream>
  2. #include <string.h>
  3.  
  4. class doubled 
  5. {
  6. private:
  7.     class sublink 
  8. 	{
  9. 	private:
  10. 		char data[30];
  11. 		sublink *next_ptr;
  12. 		sublink *previous_ptr;
  13. 		friend doubled;
  14. 	};
  15.  
  16. public:
  17. 	sublink *first_ptr;
  18. 	doubled(){first_ptr = NULL;};
  19. 	void add_item(char *item);
  20. 	void rm_item(char *item);
  21. };
  22.  
  23. void doubled::add_item(char *item)
  24. {
  25. 	sublink *new_data;
  26. 	new_data = new sublink;
  27.  
  28. 	strcpy(new_data->data, item);
  29.  
  30. 	// empty list case
  31. 	if(first_ptr == NULL)
  32. 	{
  33. 		// Only item in the list, I have no next or previous element
  34. 		new_data->previous_ptr = NULL;
  35. 		new_data->next_ptr = NULL;
  36.  
  37. 		// Make the list point to this element
  38. 		first_ptr = new_data;
  39. 	} 
  40. 	else 
  41. 	{
  42. 		sublink* iter;
  43. 		iter = first_ptr;
  44.  
  45. 		// 1 element list
  46. 		if(iter->next_ptr == NULL)
  47. 		{
  48. 			// I'm after the first and only node
  49. 			if(strcmp(iter->data, new_data->data) <= 0)
  50. 			{
  51. 				iter->next_ptr = new_data;
  52. 				new_data->previous_ptr = iter;
  53. 				new_data->next_ptr = NULL;
  54. 			}
  55. 			// I'm before the first and only node and thefore I become the new first
  56. 			else
  57. 			{
  58. 				iter->previous_ptr = new_data;
  59. 				new_data->next_ptr = iter;
  60. 				first_ptr = iter;
  61. 			}
  62. 		}
  63. 		// 2+ element list
  64. 		else
  65. 		{
  66. 			// this is never null the first time because empty list case is take care of above
  67. 			while(iter != NULL)
  68. 			{
  69. 				// Should I be inserted before the current node?
  70. 				if(strcmp(iter->data, new_data->data) >= 0)
  71. 				{
  72. 					// first node case
  73. 					if(iter->previous_ptr == NULL)
  74. 					{
  75. 						new_data->previous_ptr = NULL;
  76. 						new_data->next_ptr = iter;
  77. 						iter->previous_ptr = new_data;
  78. 						first_ptr = new_data;
  79.  
  80. 					}
  81. 					// intermediate node case
  82. 					else if(iter->next_ptr != NULL)
  83. 					{
  84. 						iter->previous_ptr->next_ptr = new_data;
  85. 						new_data->previous_ptr = iter->previous_ptr;
  86. 						new_data->next_ptr = iter;
  87. 						iter->previous_ptr = new_data;
  88. 					}
  89. 					// last node case
  90. 					else
  91. 					{
  92. 						iter->next_ptr = new_data;
  93. 						new_data->previous_ptr = iter;
  94. 						new_data->next_ptr = NULL;
  95. 					}
  96.  
  97. 					break;
  98. 				}
  99.  
  100. 				// Move to next node
  101. 				iter = iter->next_ptr;
  102. 			}
  103. 		}
  104. 	}
  105.  
  106. 	// Print the list
  107. 	std::cout << "List: " << std::endl;
  108. 	sublink* printer = first_ptr;
  109. 	while(printer != NULL)
  110. 	{
  111. 		std::cout << '\t' << printer->data << std::endl;
  112.  
  113. 		printer = printer->next_ptr;
  114. 	}
  115. 	std::cout << std::endl;
  116. }
  117.  
  118. int main(int argc, char* argv[])
  119. {
  120. 	doubled d;
  121.  
  122. 	char item[30] = "bla bla bla\0";
  123. 	char item2[30] = "meh\0";
  124. 	char item3[30] = "ahhhhhhhh\0";
  125. 	char item4[30] = "dayummmmm\0";
  126. 	d.add_item(item);
  127. 	d.add_item(item2);
  128. 	d.add_item(item3);
  129. 	d.add_item(item4);
  130.  
  131. 	std::cin.get();
  132. 	return 0;
  133. }
Success #stdin #stdout 0s 3032KB
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stdin
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Standard input is empty
stdout
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List: 
	bla bla bla

List: 
	bla bla bla
	meh

List: 
	ahhhhhhhh
	bla bla bla
	meh

List: 
	ahhhhhhhh
	bla bla bla
	meh
	dayummmmm
https://ideone.com/EAzsPZ
language:
C++ (gcc 8.3)
created:
12 years ago
visibility:
public

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