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  1. //If you are not sure what some lines of code do, try looking back at
  2. //previous example programs, notes, or ask a question.
  3.  
  4. #include <iostream>
  5.  
  6. using namespace std;
  7.  
  8.  
  9. // SEE THE LAST EXAMPLE FOR COMMENTS ON THE ACTUAL LIST DATA STRUCTURE,
  10. // COMMENTS HERE ARE ONLY ON TEMPLATE FEATURES
  11.  
  12.  
  13. // Our forward declaration has to be template
  14. template <typename T> class LinkedList;
  15.  
  16. // Here our node is templated so each node can hold an arbitrary data type
  17. template <typename T> 
  18. class node {
  19. 	// Our value paramter is of our template paramter "T"
  20. 	// This is also implemented here, in the class definition
  21. 	node(T v, node* n = NULL) {
  22. 		value = v;
  23. 		next = n;
  24. 	}
  25. 	// Don't need this to do anything
  26.  	~node() {}
  27.  
  28. 	// The value this node holds should, of course, be of generic type "T"
  29. 	T value;
  30. 	node* next;
  31.  
  32. 	// Note that we must specify that LinkedList is templated
  33. 	friend class LinkedList<T>;
  34.  
  35. 	// We can't implement a friend here, as it's not a member
  36. 	// We also have to specify what kind of list we're outputting, so we do LinkedList<type>.
  37. 	// Hence, the friend must also be templated. Note that the template declaration goes before
  38. 	// "friend," and that we must use U as our argument, as T is already defined.
  39. 	template <typename U> friend ostream& operator<<(ostream& out, const LinkedList<U>& src);
  40. };
  41.  
  42. // Here our actual list is templated to accomodate the templated nodes and arbitrary data input/output
  43. template <typename T> 
  44. class LinkedList {
  45. public:
  46. 	LinkedList() {
  47. 		head = NULL;
  48. 	}
  49. 	// We need a copy constructor for later
  50. 	LinkedList(const LinkedList& src) {
  51. 		head = NULL;
  52. 		node<T>* temp = src.head;
  53. 		while(temp) {
  54. 			addValue(temp->value);
  55. 			temp = temp->next;
  56. 		}
  57. 	}
  58. 	// We need an assignment operator for later
  59. 	LinkedList& operator=(const LinkedList& src) {
  60. 		while(head) {
  61. 			node<T>* temp = head->next;
  62. 			delete head;
  63. 			head = temp;
  64. 		}
  65. 		node<T>* temp = src.head;
  66. 		while(temp) {
  67. 			addValue(temp->value);
  68. 			temp = temp->next;
  69. 		}
  70. 	}
  71. 	~LinkedList() {
  72. 		while(head) {
  73. 			node<T>* temp = head->next;
  74. 			delete head;
  75. 			head = temp;
  76. 		}
  77. 	}
  78.  
  79. 	// Here we add a value of generic type T
  80. 	void addValue(T value) {
  81. 		head = new node<T>(value,head);
  82. 	}
  83. 	// Here we remove a value, returning generic type T
  84. 	T removeValue() {
  85. 		T result;
  86. 		if(head) {
  87. 			result = head->value;
  88. 			node<T>* temp = head->next;
  89. 			delete head;
  90. 			head = temp;
  91. 		}
  92. 		return result;
  93. 	}
  94.  
  95. 	// Again, we can't implement a friend here, and we must specify that the LinkedList uses type U
  96. 	template <typename U> friend ostream& operator<<(ostream& out, const LinkedList<U>& src);
  97.  
  98. private:
  99. 	// Our node must use generic type T
  100. 	node<T>* head;
  101. };
  102.  
  103. // Here we actually implement our friend, note the use of another template
  104. template <typename T>
  105. ostream& operator<<(ostream& out, const LinkedList<T>& src) {
  106. 	node<T>* temp = src.head;
  107. 	while(temp) {
  108. 		// Output brackets for list-of-list clarity
  109. 		// Later, we create a list of lists, so in that case "out << temp->value"
  110. 		// will actually recursively call this function 
  111. 		out << "[" << temp->value << "]";
  112. 		if(temp->next) {
  113. 			out << " -> ";
  114. 		}
  115.  
  116. 		temp = temp->next;
  117. 	}
  118.  
  119. 	return out;
  120. }
  121.  
  122. int main() {
  123. 	// Declare list using integers
  124. 	LinkedList<int> intList;
  125. 	// Declare list using floats
  126. 	LinkedList<float> floatList;
  127. 	// Delcare list using lists that use integers
  128. 	// prior to c++11, you have to leave a space between two '>' brackets in a
  129. 	// nested template, otherwise the compiler thinks you're using the ">>" operator 
  130. 	LinkedList<LinkedList<int> > listList;
  131.  
  132. 	// Output lists
  133. 	cout << "Int list: " << intList << endl;
  134. 	cout << "Float list: " << floatList << endl;
  135. 	cout << "List list: " << listList << endl;
  136.  
  137. 	// Add values to the int list
  138. 	for(int index = 0; index < 10; index++) {
  139. 		intList.addValue(index);
  140. 	}
  141.  
  142. 	// Add values to the float list
  143. 	for(float index = 0.5; index < 10; index++) {
  144. 		floatList.addValue(index);
  145. 	}
  146.  
  147. 	// Add values to list list
  148. 	for(int index = 0; index < 10; index++) {
  149. 		LinkedList<int> value;
  150. 		for(int index = 0; index < 10; index++) {
  151. 			value.addValue(index);
  152. 		}
  153. 		listList.addValue(value);
  154. 	}
  155.  
  156. 	// Output lists
  157. 	cout << "Int list: " << intList << endl;
  158. 	cout << "Float list: " << floatList << endl;
  159. 	cout << "List list: " << listList << endl;
  160.  
  161. 	system("pause");
  162. 	return 0;	
  163. }
  164.  
Success #stdin #stdout #stderr 0s 3416KB
comments (?)
stdin
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Standard input is empty
stdout
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Int list: 
Float list: 
List list: 
Int list: [9] -> [8] -> [7] -> [6] -> [5] -> [4] -> [3] -> [2] -> [1] -> [0]
Float list: [9.5] -> [8.5] -> [7.5] -> [6.5] -> [5.5] -> [4.5] -> [3.5] -> [2.5] -> [1.5] -> [0.5]
List list: [[0] -> [1] -> [2] -> [3] -> [4] -> [5] -> [6] -> [7] -> [8] -> [9]] -> [[0] -> [1] -> [2] -> [3] -> [4] -> [5] -> [6] -> [7] -> [8] -> [9]] -> [[0] -> [1] -> [2] -> [3] -> [4] -> [5] -> [6] -> [7] -> [8] -> [9]] -> [[0] -> [1] -> [2] -> [3] -> [4] -> [5] -> [6] -> [7] -> [8] -> [9]] -> [[0] -> [1] -> [2] -> [3] -> [4] -> [5] -> [6] -> [7] -> [8] -> [9]] -> [[0] -> [1] -> [2] -> [3] -> [4] -> [5] -> [6] -> [7] -> [8] -> [9]] -> [[0] -> [1] -> [2] -> [3] -> [4] -> [5] -> [6] -> [7] -> [8] -> [9]] -> [[0] -> [1] -> [2] -> [3] -> [4] -> [5] -> [6] -> [7] -> [8] -> [9]] -> [[0] -> [1] -> [2] -> [3] -> [4] -> [5] -> [6] -> [7] -> [8] -> [9]] -> [[0] -> [1] -> [2] -> [3] -> [4] -> [5] -> [6] -> [7] -> [8] -> [9]]
stderr
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sh: 1: pause: not found
https://ideone.com/5pim2e
language:
C++14 (gcc 8.3)
created:
7 years ago
visibility:
secret

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