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Liam's Blog

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If history repeats itself, and the unexpected always happens, how incapable must Man be of learning from experience?—George Bernard Shaw.

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<a href="/2018/06/13/Fundamentals-of-Python/" class="post-title-link" itemprop="url">Fundamentals of Python</a>

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<h3 id="The-Python-Conceptual-Hierarchy"><a href="#The-Python-Conceptual-Hierarchy" class="headerlink" title="The Python Conceptual Hierarchy"></a>The Python Conceptual Hierarchy</h3><ol>

<li>Programs are composed of modules</li>

<li>Modules contain statements</li>

<li>Statements contain expressions</li>

<li>Expressions create and process objects</li>

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<a href="/2018/05/30/C-Implementations-Linked-List-based-Stack/" class="post-title-link" itemprop="url">C++ Implementations: Linked List-Based Stack</a>

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<h1 id="Implementation"><a href="#Implementation" class="headerlink" title="Implementation"></a>Implementation</h1>

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<a href="/2018/05/28/C-notes-for-financial-mathematics/" class="post-title-link" itemprop="url">C++ notes for financial mathematics</a>

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NaN:aN

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<li><figure class="highlight c++"><table><tr><td class="gutter"><pre>1 2 3 </pre></td><td class="code"><pre>Inf: positive infinity -Inf: negative infinity NaN: not a number </pre></td></tr></table></figure>

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<li>Noting that two decimals can only be approximately equal.

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<li>Casting an int to a float is risky since the float data type uses binary scientific notation with only a handful of significant figures. So an int cannot be represented precisely using a float.

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<a href="/2018/05/28/C-Implementations-Doubly-Circular-Linked-List/" class="post-title-link" itemprop="url">C++ Implementations - Doubly Circular Linked List</a>

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<h1 id="Header-file"><a href="#Header-file" class="headerlink" title="Header file"></a>Header file</h1><figure class="highlight c++"><table><tr><td class="gutter"><pre>1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 </pre></td><td class="code"><pre>#ifndef CIRCULARLINKEDLIST_H_ #define CIRCULARLINKEDLIST_H_ #include <cstddef> #include <iostream> template <typename T> class CircularLinkedList{ struct Node; public: typedef std::size_t size_type; typedef T value_type; // default constructor CircularLinkedList(): sentinel(create_sentinel()), count(0) { std::cout << "default constructor" << std::endl; } CircularLinkedList(size_type, const T&val = T()); CircularLinkedList(const CircularLinkedList&); CircularLinkedList& operator= (const CircularLinkedList&); ~CircularLinkedList(); bool empty() const { return sentinel->next == sentinel; } size_type size() const { return count; } Node* begin() { return sentinel->next; } const Node* begin() const { return sentinel->next; } Node* end() { return sentinel; } const Node* end() const { return sentinel; } void clear(); void push_front(const T&); void push_back(const T&); void insert(size_type, const T&); void pop_front(); void pop_back(); void erase(size_type); void reverse(); void remove(const T&); private: struct Node{ T data; Node* prev; Node* next; }; Node* sentinel; size_type count; Node* create_sentinel(){ Node* nil = new Node; nil->prev = nil; nil->next = nil; return nil; } Node* create(const T&val){ Node* new_node = new Node; new_node->data = val; new_node->prev = sentinel; new_node->next = sentinel; return new_node; } }; // O(n) template <typename T> CircularLinkedList<T>::CircularLinkedList(size_type n, const T& val) : sentinel(create_sentinel()), count(0){ std::cout << "construtor with parameters" << std::endl; Node* current = sentinel; while(count != n){ current->next = create(val); current->next->prev = current; current = current->next; ++count; } sentinel->prev = current; } // O(n) template <typename T> CircularLinkedList<T>::CircularLinkedList(const CircularLinkedList& l) : sentinel(create_sentinel()), count(0){ std::cout << "copy constructor" << std::endl; Node* current = sentinel; const Node* temp = l.begin(); while(count != l.size()){ current->next = create(temp->data); current->next->prev = current; current = current->next; temp = temp->next; ++count; } sentinel->prev = current; } // O(n) template <typename T> CircularLinkedList<T>& CircularLinkedList<T>::operator= (const CircularLinkedList& l){ std::cout << "assignment operator" << std::endl; if(&l != this){ clear(); if(!l.empty()){ Node* current = sentinel; const Node* temp = l.begin(); while(count != l.size()){ current->next = create(temp->data); current->next->prev = current; current = current->next; temp = temp->next; ++count; } sentinel->prev = current; } } return *this; } // O(n) template <typename T> void CircularLinkedList<T>::clear(){ while(sentinel->next != sentinel){ Node* temp = sentinel->next; sentinel->next = temp->next; sentinel->next->prev = sentinel; delete temp; --count; } } // O(n) template <typename T> CircularLinkedList<T>::~CircularLinkedList() { clear(); delete sentinel; sentinel = nullptr; std::cout << "destructor" << std::endl; } // O(1) template <typename T> void CircularLinkedList<T>::push_front(const T& val){ Node* new_node = create(val); new_node->next = sentinel->next; new_node->next->prev = new_node; sentinel->next = new_node; new_node->prev = sentinel; ++count; } // O(n) template <typename T> void CircularLinkedList<T>::push_back(const T& val){ Node* current = sentinel; while(current->next != sentinel) current = current->next; current->next = create(val); current->next->prev = current; sentinel->prev = current->next; ++count; } // O(n) template <typename T> void CircularLinkedList<T>::insert(size_type position, const T& val){ if(position < 1 || position > size()) throw std::domain_error("Invalid Position"); Node* current = sentinel; Node* new_node = create(val); for(size_type i = 0; i != position; ++i) current = current->next; current->prev->next = new_node; new_node->prev = current->prev; new_node->next = current; current->prev = new_node; ++count; } // O(1) template <typename T> void CircularLinkedList<T>::pop_front(){ erase(1); } // O(n) template <typename T> void CircularLinkedList<T>::pop_back(){ erase(size()); } // O(n) template <typename T> void CircularLinkedList<T>::erase(size_type position){ if(position < 1 || position > size()) throw std::domain_error("Invalid Position"); Node* current = sentinel; for(size_type i = 0; i != position; ++i) current = current->next; current->next->prev = current->prev; current->prev->next = current->next; delete current; --count; } // O(n) template <class T> void CircularLinkedList<T>::remove(const T& val){ Node* current = sentinel; while(current->next != sentinel){ if(current->next->data == val){ Node* temp = current->next; current->next = temp->next; temp->next->prev = current; delete temp; --count; }else current = current->next; } } // O(n) template <class T> void CircularLinkedList<T>::reverse(){ if (size() < 2) return; sentinel->prev = sentinel->next; Node* current = sentinel; Node* NEXT; while(current->next != sentinel){ NEXT = current->next; current->next = current->prev; current->prev = NEXT; current = NEXT; } current->next = current->prev; current->prev = sentinel; sentinel->next = current; } #endif /* CIRCULARLINKEDLIST_H_ */ </pre></td></tr></table></figure>

<h1 id="Test-program-and-results"><a href="#Test-program-and-results" class="headerlink" title="Test program and results"></a>Test program and results</h1><figure class="highlight c++"><table><tr><td class="gutter"><pre>1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 </pre></td><td class="code"><pre>/* * this program tests all operations that provided by the * CircularLinkedList<T> class * created by Liam on: 28 Apr 2018 */ #include <iostream> #include "CircularLinkedList.h" using std::endl; using std::cout; // print and reverse print template <class T> void print(T& l){ cout << "print in order: "; for(auto i = l.begin(); i != l.end(); i = i->next) cout << i->data << " "; cout << endl; cout << "print in reverse: "; for(auto i = (l.end())->prev; i != l.end(); i = i->prev) cout << i->data << " "; cout << endl; } int main(){ { // construct an empty linked list CircularLinkedList<int> s; if(s.empty()) cout << "s is an empty linked list\n" "the size of s1 is: " << s.size() << endl; // call destructor once reaches the end of this block } cout << endl; { // construct a linked list that contains 10 elements, all values are 100 CircularLinkedList<int> s(10, 100); // construct a linked list by copying from s CircularLinkedList<int> s_copy(s); if(!s.empty() && !s_copy.empty()){ cout << "the size of s is: " << s.size() << endl; cout << "the size of s_copy is: " << s_copy.size() << endl; } // print the contents of s_copy print(s_copy); // call destructor twice } cout << endl; { // assignment CircularLinkedList<int> s(10, 100); CircularLinkedList<int> s_copy; s_copy = s; // print the contents of s_copy print(s_copy); } cout << endl; { // push front CircularLinkedList<double> s; for(int i = 5; i != 0; --i) s.push_front(i); cout << "after adding elements at front:\n"; print(s); // push back for(int i = 5; i != 0; --i) s.push_back(i); cout << "after adding elements at the end:\n"; print(s); // insert at position 5 for(int i = 5; i != 0; --i) s.insert(i, 0); cout << "after inserting elements in-between:\n"; print(s); // delete from the begining for(int i = 5; i != 0; --i) s.pop_front(); cout << "after deleting from the begining:\n"; print(s); // delete from the end for(int i = 5; i != 0; --i){ s.pop_back(); } cout << "after deleting from the end:\n"; print(s); // erase at in-between positions for(int i = 3; i != 0; --i) s.erase(3); cout << "after deleting from other positions:\n"; print(s); } cout << endl; { // remove CircularLinkedList<int> s(5, 5); for(int i = 5; i != 0; --i) s.insert(5, i); cout << "at present:\n"; print(s); s.remove(5); cout << "after removing all elements:\n"; print(s); } cout << endl; { // test reverse function CircularLinkedList<int> s; for(int i = 0; i != 10; ++i) s.push_back(i); cout << "at present, s contains following elements:\n"; print(s); s.reverse(); cout << "after reverse:\n"; print(s); } return 0; } </pre></td></tr></table></figure>

Outputs:

<figure class="highlight plain"><table><tr><td class="gutter"><pre>1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 </pre></td><td class="code"><pre>default constructor s is an empty linked list the size of s1 is: 0 destructor construtor with parameters copy constructor the size of s is: 10 the size of s_copy is: 10 print in order: 100 100 100 100 100 100 100 100 100 100 print in reverse: 100 100 100 100 100 100 100 100 100 100 destructor destructor construtor with parameters default constructor assignment operator print in order: 100 100 100 100 100 100 100 100 100 100 print in reverse: 100 100 100 100 100 100 100 100 100 100 destructor destructor default constructor after adding elements at front: print in order: 1 2 3 4 5 print in reverse: 5 4 3 2 1 after adding elements at the end: print in order: 1 2 3 4 5 5 4 3 2 1 print in reverse: 1 2 3 4 5 5 4 3 2 1 after inserting elements in-between: print in order: 0 1 0 2 0 3 0 4 0 5 5 4 3 2 1 print in reverse: 1 2 3 4 5 5 0 4 0 3 0 2 0 1 0 after deleting from the begining: print in order: 3 0 4 0 5 5 4 3 2 1 print in reverse: 1 2 3 4 5 5 0 4 0 3 after deleting from the end: print in order: 3 0 4 0 5 print in reverse: 5 0 4 0 3 after deleting from other positions: print in order: 3 0 print in reverse: 0 3 destructor construtor with parameters at present: print in order: 5 5 5 5 1 2 3 4 5 5 print in reverse: 5 5 4 3 2 1 5 5 5 5 after removing all elements: print in order: 1 2 3 4 print in reverse: 4 3 2 1 destructor default constructor at present, s contains following elements: print in order: 0 1 2 3 4 5 6 7 8 9 print in reverse: 9 8 7 6 5 4 3 2 1 0 after reverse: print in order: 9 8 7 6 5 4 3 2 1 0 print in reverse: 0 1 2 3 4 5 6 7 8 9 destructor </pre></td></tr></table></figure>

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<a href="/2018/05/26/C-Implementations-Circular-Doubly-Linked-List/" class="post-title-link" itemprop="url">C++ Implementations: Singly Circular Linked List with a sentinel</a>

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<h1 id="Header-file"><a href="#Header-file" class="headerlink" title="Header file"></a>Header file</h1><figure class="highlight c++"><table><tr><td class="gutter"><pre>1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 </pre></td><td class="code"><pre>#ifndef CIRCULARLINKEDLIST_H_ #define CIRCULARLINKEDLIST_H_ #include <cstddef> #include <iostream> template <typename T> class CircularLinkedList{ struct Node; public: typedef std::size_t size_type; typedef T value_type; // create an empty linked list CircularLinkedList(): sentinel(create_sentinel()), count(0){ std::cout << "default constructor" << std::endl; } // create an linked list with user supplied size and value explicit CircularLinkedList(size_type, const T& val = T()); // copy constructor CircularLinkedList(const CircularLinkedList&); // assignment operator CircularLinkedList& operator=(const CircularLinkedList&); // destructor ~CircularLinkedList() { clear(); delete sentinel; sentinel = nullptr; std::cout << "destructor" << std::endl; } void clear(); bool empty() const { return sentinel == sentinel->next; } size_type size() const { return count; } Node* begin() { return sentinel->next; } const Node* begin() const { return sentinel->next; } Node* end() { return sentinel; } const Node* end() const { return sentinel; } // insert at begining void push_front(const T&); // insert at the end void push_back(const T&); // insert at the nth position, that is, after (n-1)the position // the range of position is [1, size()] void insert(size_type, const T&); // delete at the begining void pop_front(); // delete the last element void pop_back(); // delete at nth position void erase(size_type); // reverse the order iteratively void reverse(); // remove elements with specific values void remove(const T&); private: struct Node{ T data; Node* next; }; Node* sentinel; size_type count; Node* create_sentinel(){ Node* nil = new Node; nil->next = nil; return nil; } Node* create(const T& val = T()){ Node* new_node = new Node; new_node->data = val; new_node->next = sentinel; return new_node; } }; // O(n) template <typename T> CircularLinkedList<T>::CircularLinkedList(size_type n, const T& val): sentinel(create_sentinel()), count(0){ std::cout << "constructor with parameters" << std::endl; Node* current = sentinel; while(count != n){ current->next = create(val); current = current->next; ++count; } } // O(n) template <typename T> CircularLinkedList<T>::CircularLinkedList(const CircularLinkedList& l): sentinel(create_sentinel()), count(0){ Node* current = sentinel; const Node* temp = l.begin(); while(temp != l.end()){ current->next = create(temp->data); current = current->next; temp = temp->next; ++count; } } // O(n) template <typename T> CircularLinkedList<T>& CircularLinkedList<T>::operator= (const CircularLinkedList& l){ if(&l != this){ clear(); Node* current = sentinel; const Node* temp = l.begin(); while(temp != l.end()){ current->next = create(temp->data); current = current->next; temp = temp->next; ++count; } } return *this; } // O(n) template <typename T> void CircularLinkedList<T>::clear(){ Node* current = sentinel; if(current->next != sentinel){ Node* temp = current->next; current->next = temp->next; delete temp; --count; } } // O(1) template <class T> void CircularLinkedList<T>::push_front(const T& val) { Node* current = sentinel; Node* new_node = create(val); new_node->next = current->next; current->next = new_node; ++count; } // O(n) template <class T> void CircularLinkedList<T>::push_back(const T& val) { Node* current = sentinel; while(current->next != sentinel) current = current->next; current->next = create(val); ++count; } // O(n) template <class T> void CircularLinkedList<T>::insert(size_type position, const T& val){ if(position < 1 || position > size()) throw std::domain_error("Invalid Position"); Node* new_node = create(val); Node* temp = sentinel; for (size_type i = 0; i != position-1; ++i) temp = temp->next; new_node->next = temp->next; temp->next = new_node; ++count; } // O(1) template <class T> void CircularLinkedList<T>::pop_front(){ erase(1); } // O(n) template <class T> void CircularLinkedList<T>::pop_back(){ erase(size()); } // O(n) template <class T> void CircularLinkedList<T>::erase(size_type position){ if(position < 1 || position > size()) throw std::domain_error("Invalid Position"); Node* current = sentinel; for(size_type i = 0; i != position - 1; ++i) current = current->next; Node* temp = current->next; current->next = temp->next; delete temp; --count; } // O(n) template <class T> void CircularLinkedList<T>::remove(const T& val){ Node* current = sentinel; while(current->next != sentinel){ if(current->next->data == val){ Node* temp = current->next; current->next = temp->next; delete temp; --count; }else current = current->next; } } // O(n) template <class T> void CircularLinkedList<T>::reverse(){ if (size() < 2) return; Node* current = sentinel->next; Node* PREV = sentinel; Node* NEXT; while(current->next != sentinel){ NEXT = current->next; current->next = PREV; PREV = current; current = NEXT; } current->next = PREV; sentinel->next = current; } #endif /* CIRCULARLINKEDLIST_H_ */ </pre></td></tr></table></figure>

<h1 id="Test-program-and-results"><a href="#Test-program-and-results" class="headerlink" title="Test program and results"></a>Test program and results</h1><figure class="highlight c++"><table><tr><td class="gutter"><pre>1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 </pre></td><td class="code"><pre>/* * this program tests all operations that provided by the * CircularLinkedList<T> class * created by Liam on: 28 May 2018 */ #include <iostream> #include "CircularLinkedList.h" using std::endl; using std::cout; template <class Pointer> void print(Pointer begin, Pointer end){ while(begin != end){ cout << begin->data << " "; begin = begin->next; } cout<< endl; } int main(){ { // construct an empty linked list CircularLinkedList<int> s; if(s.empty()) cout << "s is an empty linked list\n" "the size of s1 is: " << s.size() << endl; // call destructor once reaches the end of this block } cout << endl; { // construct a linked list that contains 10 elements, all values are 100 CircularLinkedList<int> s(10, 100); // construct a linked list by copying from s CircularLinkedList<int> s_copy(s); if(!s.empty() && !s_copy.empty()){ cout << "the size of s is: " << s.size() << endl; cout << "the size of s_copy is: " << s_copy.size() << endl; } // print the contents of s_copy cout << "all elements in s_copy: "; print(s.begin(), s.end()); // call destructor twice } cout << endl; { // assignment CircularLinkedList<int> s(10, 100); CircularLinkedList<int> s_copy; s_copy = s; // print the contents of s_copy cout << "all elements in s_copy: "; print(s_copy.begin(), s_copy.end()); } cout << endl; { // push front CircularLinkedList<double> s; for(int i = 5; i != 0; --i) s.push_front(i); cout << "after adding elements at front, s becomes: "; print(s.begin(), s.end()); // push back for(int i = 5; i != 0; --i) s.push_back(i); cout << "after adding elements at the end, s becomes: "; print(s.begin(), s.end()); // insert at position 5 for(int i = 5; i != 0; --i) s.insert(i, 0); cout << "after inserting elements in-between, s becomes: "; print(s.begin(), s.end()); // delete from the begining for(int i = 5; i != 0; --i) s.pop_front(); cout << "after deleting from the begining, s becomes: "; print(s.begin(), s.end()); // delete from the end for(int i = 5; i != 0; --i) s.pop_back(); cout << "after deleting from the end, s becomes: "; print(s.begin(), s.end()); // erase at in-between positions for(int i = 3; i != 0; --i) s.erase(3); cout << "after deleting from other positions, s becomes: "; print(s.begin(), s.end()); } cout << endl; { // remove CircularLinkedList<int> s(5, 5); for(int i = 5; i != 0; --i) s.insert(5, i); cout << "at present, s contains following elements: "; print(s.begin(), s.end()); s.remove(5); cout << "after removing all elements equal 5, s becomes: "; print(s.begin(), s.end()); } cout << endl; { // test reverse function CircularLinkedList<int> s; for(int i = 0; i != 10; ++i) s.push_back(i); cout << "at present, s contains following elements: "; print(s.begin(), s.end()); s.reverse(); cout << "reverse: "; print(s.begin(), s.end()); s.reverse(); cout << "reverse again: "; print(s.begin(), s.end()); } return 0; } </pre></td></tr></table></figure>

Outputs:

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<a href="/2018/05/26/C-Implementations-Doubly-Linked-List/" class="post-title-link" itemprop="url">C++ Implementations: Doubly Linked List</a>

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Symbols count in article:

Reading time ≈

NaN:aN

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<h1 id="Head-files"><a href="#Head-files" class="headerlink" title="Head files"></a>Head files</h1><figure class="highlight c++"><table><tr><td class="gutter"><pre>1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 </pre></td><td class="code"><pre>#ifndef DOUBLYLINKEDLIST_H_ #define DOUBLYLINKEDLIST_H_ #include <cstddef> #include <stdexcept> #include <iostream> template <typename T> class DoublyLinkedList{ struct Node; public: typedef std::size_t size_type; typedef T value_type; // default constructor DoublyLinkedList(): ptrToHead(nullptr), count(0){ std::cout << "default constructor" << std::endl; } // constructor with parameters explicit DoublyLinkedList(size_type, const T&val = T()); // copy constructor DoublyLinkedList(const DoublyLinkedList&); // assignment operator DoublyLinkedList& operator=(const DoublyLinkedList&); // destructor ~DoublyLinkedList() { std::cout << "destructor" << std::endl; clear(); } void clear(); bool empty() const { return ptrToHead == nullptr; } size_type size() const { return count; } Node* begin() { return ptrToHead; } const Node* begin() const { return ptrToHead; } void push_front(const T&); void push_back(const T&); void insert(size_type, const T&); void pop_front(); void pop_back(); void erase(size_type); void remove(const T&); void reverse(); private: struct Node{ T data; Node* prev; Node* next; }; Node* ptrToHead; size_type count; Node* create(const T& val){ Node* new_node = new Node; new_node->data = val; new_node->prev = nullptr; new_node->next = nullptr; return new_node; } }; // constructor with parameters:O(n) template <typename T> DoublyLinkedList<T>::DoublyLinkedList(size_type n, const T&val){ std::cout << "constructor with parameters" << std::endl; if(n > 0){ ptrToHead = create(val); count = 1; Node* current = ptrToHead; while(count != n){ current->next = create(val); current->next->prev = current; current = current->next; ++count; } } } // copy constructor: O(n) template <typename T> DoublyLinkedList<T>::DoublyLinkedList(const DoublyLinkedList& l) : ptrToHead(nullptr), count(0){ std::cout << "copy constructor" << std::endl; if(!l.empty()){ ptrToHead = create(l.begin()->data); count = 1; const Node* temp = l.begin(); Node* current = ptrToHead; while(count != l.size()){ current->next = create(temp->next->data); current->next->prev = current; current = current->next; temp = temp->next; ++count; } } } // assignment operator: O(n) template <typename T> DoublyLinkedList<T>& DoublyLinkedList<T>::operator= (const DoublyLinkedList& l) { std::cout << "assignment operator" << std::endl; if(&l != this){ clear(); if(!l.empty()){ ptrToHead = create(l.begin()->data); count = 1; const Node* temp = l.begin(); Node* current = ptrToHead; while(count != l.size()){ current->next = create(temp->next->data); current->next->prev = current; current = current->next; temp = temp->next; ++count; } } } return *this; } // O(n) template <typename T> void DoublyLinkedList<T>::clear(){ Node* current = ptrToHead; while(current != nullptr){ ptrToHead = ptrToHead->next; delete current; current = ptrToHead; --count; } } // O(1) template <typename T> void DoublyLinkedList<T>::push_front(const T& val){ Node* new_node = create(val); if(ptrToHead != nullptr){ new_node->next = ptrToHead; ptrToHead->prev = new_node; } ptrToHead = new_node; ++count; } // O(n) template <typename T> void DoublyLinkedList<T>::push_back(const T& val){ Node* new_node = create(val); if(ptrToHead == nullptr){ ptrToHead = new_node; ++count; return; } Node* current = ptrToHead; while(current->next != nullptr) current = current->next; current->next = new_node; new_node->prev = current; ++count; } // O(n) template <typename T> void DoublyLinkedList<T>::insert(size_type position, const T& val){ if(position < 1 || position > size()) throw std::domain_error("Invalid Position"); else if(position == 1) push_front(val); else{ Node* new_node = create(val); Node* current = ptrToHead; for(size_type i = 0; i != position - 1; ++i) current = current->next; current->prev->next = new_node; new_node->next = current; new_node->prev = current->prev; current->prev = new_node; ++count; } } // O(1) template <typename T> void DoublyLinkedList<T>::pop_front(){ erase(1); } // O(n) template <typename T> void DoublyLinkedList<T>::pop_back(){ erase(size()); } // O(n) template <typename T> void DoublyLinkedList<T>::erase(size_type position){ if(position < 1 || position > size()) throw std::domain_error("Invalid Position"); Node* current = ptrToHead; if(size() == 1){ ptrToHead = nullptr; }else if(position == 1){ ptrToHead = ptrToHead->next; ptrToHead->prev = nullptr; }else if(position == size()){ while(current->next != nullptr) current = current->next; current->prev->next = nullptr; }else{ for (size_type i = 0; i != position - 1; ++i){ current = current->next; } current->next->prev = current->prev; current->prev->next = current->next; } delete current; --count; } // O(n) template <typename T> void DoublyLinkedList<T>::remove(const T& val){ Node* current = ptrToHead; while(current != nullptr){ if(current->data == val){ Node* temp = current->next; if(current->prev == nullptr){ ptrToHead = ptrToHead->next; if(ptrToHead != nullptr){ ptrToHead->prev = nullptr; } }else if(current->next == nullptr){ current->prev->next = nullptr; }else{ current->next->prev = current->prev; current->prev->next = current->next; } delete current; current = temp; }else current = current->next; } } // O(n) template <typename T> void DoublyLinkedList<T>::reverse(){ Node* current = ptrToHead; Node* PREV = nullptr; while(current != nullptr){ current->prev = current->next; current->next = PREV; PREV = current; current = current->prev; } ptrToHead = PREV; } #endif /* DOUBLYLINKEDLIST_H_ */ </pre></td></tr></table></figure>

<h1 id="Test-program-and-results"><a href="#Test-program-and-results" class="headerlink" title="Test program and results"></a>Test program and results</h1><figure class="highlight c++"><table><tr><td class="gutter"><pre>1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 </pre></td><td class="code"><pre>/* * this program tests all operations that provided by the * DoublyLinkedList<T> class * created by Liam on: 28 Apr 2018 */ #include <iostream> #include "DoublyLinkedList.h" using std::endl; using std::cout; // print and reverse print template <class T> void print(T& l){ cout << "print in order: "; for(auto it = l.begin(); it != nullptr; it = it->next){ cout << it->data << " "; } cout << "\n" << "print in reverse: "; auto it = l.begin(); while(it->next != nullptr){ it = it->next; } while(it != nullptr){ cout << it->data << " "; it = it->prev; } cout << endl; } int main(){ { // construct an empty linked list DoublyLinkedList<int> s; if(s.empty()) cout << "s is an empty linked list\n" "the size of s1 is: " << s.size() << endl; // call destructor once reaches the end of this block } cout << endl; { // construct a linked list that contains 10 elements, all values are 100 DoublyLinkedList<int> s(10, 100); // construct a linked list by copying from s DoublyLinkedList<int> s_copy(s); if(!s.empty() && !s_copy.empty()){ cout << "the size of s is: " << s.size() << endl; cout << "the size of s_copy is: " << s_copy.size() << endl; } // print the contents of s_copy print(s_copy); // call destructor twice } cout << endl; { // assignment DoublyLinkedList<int> s(10, 100); DoublyLinkedList<int> s_copy; s_copy = s; // print the contents of s_copy print(s_copy); } cout << endl; { // push front DoublyLinkedList<double> s; for(int i = 5; i != 0; --i) s.push_front(i); cout << "after adding elements at front:\n"; print(s); // push back for(int i = 5; i != 0; --i) s.push_back(i); cout << "after adding elements at the end:\n"; print(s); // insert at position 5 for(int i = 5; i != 0; --i) s.insert(i, 0); cout << "after inserting elements in-between:\n"; print(s); // delete from the begining for(int i = 5; i != 0; --i) s.pop_front(); cout << "after deleting from the begining:\n"; print(s); // delete from the end for(int i = 5; i != 0; --i){ s.pop_back(); } cout << "after deleting from the end:\n"; print(s); // erase at in-between positions for(int i = 3; i != 0; --i) s.erase(3); cout << "after deleting from other positions:\n"; print(s); } cout << endl; { // remove DoublyLinkedList<int> s(5, 5); for(int i = 5; i != 0; --i) s.insert(5, i); cout << "at present:\n"; print(s); s.remove(5); cout << "after removing all elements:\n"; print(s); } cout << endl; { // test reverse function DoublyLinkedList<int> s; for(int i = 0; i != 10; ++i) s.push_back(i); cout << "at present, s contains following elements:\n"; print(s); s.reverse(); cout << "after reverse:\n"; print(s); } return 0; } </pre></td></tr></table></figure>

Outputs:

<figure class="highlight plain"><table><tr><td class="gutter"><pre>1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 </pre></td><td class="code"><pre>default constructor s is an empty linked list the size of s1 is: 0 destructor constructor with parameters copy constructor the size of s is: 10 the size of s_copy is: 10 print in order: 100 100 100 100 100 100 100 100 100 100 print in reverse: 100 100 100 100 100 100 100 100 100 100 destructor destructor constructor with parameters default constructor assignment operator print in order: 100 100 100 100 100 100 100 100 100 100 print in reverse: 100 100 100 100 100 100 100 100 100 100 destructor destructor default constructor after adding elements at front: print in order: 1 2 3 4 5 print in reverse: 5 4 3 2 1 after adding elements at the end: print in order: 1 2 3 4 5 5 4 3 2 1 print in reverse: 1 2 3 4 5 5 4 3 2 1 after inserting elements in-between: print in order: 0 1 0 2 0 3 0 4 0 5 5 4 3 2 1 print in reverse: 1 2 3 4 5 5 0 4 0 3 0 2 0 1 0 after deleting from the begining: print in order: 3 0 4 0 5 5 4 3 2 1 print in reverse: 1 2 3 4 5 5 0 4 0 3 after deleting from the end: print in order: 3 0 4 0 5 print in reverse: 5 0 4 0 3 after deleting from other positions: print in order: 3 0 print in reverse: 0 3 destructor constructor with parameters at present: print in order: 5 5 5 5 1 2 3 4 5 5 print in reverse: 5 5 4 3 2 1 5 5 5 5 after removing all elements: print in order: 1 2 3 4 print in reverse: 4 3 2 1 destructor default constructor at present, s contains following elements: print in order: 0 1 2 3 4 5 6 7 8 9 print in reverse: 9 8 7 6 5 4 3 2 1 0 after reverse: print in order: 9 8 7 6 5 4 3 2 1 0 print in reverse: 0 1 2 3 4 5 6 7 8 9 destructor </pre></td></tr></table></figure>

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<a href="/2018/05/19/C-Implementations-Singly-Linked-List/" class="post-title-link" itemprop="url">C++ Implementations: Singly Linked List</a>

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Symbols count in article:

20k

Reading time ≈

18 mins.

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<h1 id="Logical-View"><a href="#Logical-View" class="headerlink" title="Logical View"></a>Logical View</h1>How to efficiently store a sequence of values (aka. a List) of a given type is crucial for any non-trivial program due to the limited memory. The way we store or organsize data introduces an important concept, that is, data structures. A data structure is proposed to manage data in a specific way so that we can use it efficiently according to specific needs.

In C++/C, the most common facility we use is so called built-in array, which stores a given number of elements in a contiguous memory block. All elements are stored in certain order indicated by their addresses. When we want to access any one of the elements, we pass the order of that element to the computer. Then the computer will calculate the address of that element based on the initial address of the array, and then return us the associated value. Since the addresses are contiguous and the size of memory occupied by the given type is fixed, we can always get any element in constant time: there is only one arithmetic operation needed. Naturally, we can modify any one of elements in constant time as well. However, the shortingcoming is obvious: an array has fixed length. There are two ways to solve this problem, one is that we can preset a large enough size for the array, however, doing so is very inefficient in terms of memory usage. Another way is to dynamically allocated an array when it is needed. However, doing so possibly invalidates all pointers/iterators as all elements are moved to a new allocated storage, which is also very inefficient in terms of time cost(O(n)). Even if the allocated storage is sufficient, any modifications of the array, such as, insert or delete element, also invalidates parts or all of the pointers/iterators, and hence these operations have high time cost: O(n).

An alternative data structure is named Linked List, which stores data in a noncontinuous memory space through a manner that each element are connected and ordered by pointers. More specific, an element of a singly linked list is an single object (aka. Linked Node) that contains two members: one is the data stored in the object, and the other is the address (i.e. a pointer variable) of the next element.

<h1 id="Basic-Operations"><a href="#Basic-Operations" class="headerlink" title="Basic Operations"></a>Basic Operations</h1>The entrance of a singly linked list is a pointer to the Head Node, i.e. the first Linked Node. If the linked list is empty, the pointer to the Head Node is a nullptr. To access one element, we have to start from the Head Node and move one Node by one Node. Therefore, unlike the array, the time to access elements of the linked list is proportational to the size of the linked list, that is, the time complexity is O(n). Naturally if we want to insert or delete one element into/from the list, we have to find the position or the specific element first. The time complexity is also O(n). One advantage compared to the array is that it doesn’t worry about the size of the storage. We do not need to preset the length of the list and hence no extra memory is wasted. But it does need extra memory for storing the pointer variable in each Linked Node. Another advantage is that the operations such as insert or delete doesn’t change other elements, which is crucial for us when we manipulate an object by pointers or iterators. Now let’s briefly summarize these two elementary data structures: Array and Linked List.

<table>

<thead>

<tr>

<th align="left">Array</th>

<th align="left">Linked List</th>

</tr>

</thead>

<td align="left">Cost of accessing an element of an element</td>

</tr>

<tr>

<td align="left">Memory requirement</td>

<td align="left">Fixed size: used memory and unused memory</td>

<td align="left">No unused memory but need extra memory for pointer variables</td>

</tr>

<tr>

<td align="left">Cost of Inserting or deleting an element</td>

<td align="left">Inserting at beging: O(n); Insering at the end: O(1) if there exists unused memory but O(n) is the array is full; Inserting at middle: O(n)</td>

<td align="left">Inserting at begining:O(1); Inserting at the end: O(n); Inserting at middle: O(n)</td>

</tr>

<tr>

<td align="left">Source:<a href="https://www.youtube.com/watch?v=hNP72JdOIgY&index=17&list=PL2_aWCzGMAwI3W_JlcBbtYTwiQSsOTa6P" target="_blank" rel="noopener">mycodeschool</a></td>

</tr>

</tbody></table>

From above table, we can see that whether to use an array or a linked list depends on that what is the most frequent operation the program performs and what is the size of the data structure.

<h1 id="Implementations"><a href="#Implementations" class="headerlink" title="Implementations"></a>Implementations</h1>To define a abstract data type based on the singly linked list, the first step is to write the Linked Node:

The Node struct is templated for satisfying different underlying types. It contains two items: one is named data which for storing values of T type and ther other named next which is a pointer to a Node object. Next we define the class type based on the singly linked list model described above. In fact, we can incorporate the Node type into our singly linked list class as a private member for the purpose of hidding the implementation details. As mentioned above, the only information we know is the pointer to the Head Node, therefore, I declare a private member ptrToHead to indicate the address of the Head Node. Also, I define a unsigned integer to count the number of elements stored in a linked list. For the sake of convenience, I write a private function create to create a Node with a particular value. Following code shows the full view of the SinglyLinkedList class template. Noting that this implementation is not a STL style implementation.

Let’s define the special members first:

<h2 id="constructors"><a href="#constructors" class="headerlink" title="constructors"></a>constructors</h2>The default constructor initializes the ptrToHead to nullptr and count to 0, hence constructs an empty linked list. The second constructor constructs a linked list with a size and a value of T type. If no value supplied, the data member in each Node will be default-initialized or value-initialized depending on whether there exists a user-defined default constructor in the definition of T type. Also I specify this constructor as explicit to avoid potential type conversion. To validate my implementation, I instrument these special members by adding outputs when these members are called.

The logic is simple: first create the Head Node and store its address into ptrToHead, at the same time, update the count to 1 representing that currently we have one element in our linked list; Then, create the rest Nodes and link one by one. We use a temporary pointer to move forward as we don’t want to modify the ptrToHead. The time cost is proportional to the length of the linked list and therefore the time complexity is big oh of n, where n represents the number of elements stored in the linked list.

Next is the copy constructor which controls the copy operation. The definition is similar to above constructor except that, the copy constructor constructs an object using values stored in the argument. If the argument is an empty linked list, we construct an empty linked list as well through the initialization list.

The assignment operator is similar to our copy costructor except that it needs to obliterate the old values stored in the left-hand side operand. If the argument is an empty linked list, we only need to execute the clear() function to delete all nodes (if exist) to get an empty linked list.

<h2 id="destructor-amp-clear-member"><a href="#destructor-amp-clear-member" class="headerlink" title="destructor & clear member"></a>destructor & clear member</h2>The destructor is implemented by executing the clear() function.

Due to the ptrToHead is the only entrance for us, we cannot delete it directly. Therefore, we do it by virtue of a temporary pointer, which points to the Node to be deleted. For example, let it points to the Head Node, then we can release the ptrToHead and let the ptrToHead points to our next Node, and then we clear the Head Node by delete the temporary pointer.

<h2 id="push-front-push-back-insert"><a href="#push-front-push-back-insert" class="headerlink" title="push_front, push_back, insert"></a>push_front, push_back, insert</h2>The push_front means that we can add a new element at the very begining of our linked list. It is simple to do this, making the ptrToHead points to our new Node. But noting that when the linked list is not empty, we should stores the address of the original Head Node into the next member of our new Node.

The case of appending a new Node at the end of the linked list is a little bit complex. The function is shown below.

If the linked list is empty, we simply create a new Node and let ptrToHead points to the new Node. If the linked list is not empty, we need to let the next member of the last Node points to the newly created Node. To find the address of the last Node, we use the condition:

<figure class="highlight c++"><table><tr><td class="gutter"><pre>1 </pre></td><td class="code"><pre>temp->next == nullptr </pre></td></tr></table></figure>

This condition stops the while loop and by then, temp is the address of the last Node.

Now we consider the case that inserting a new Node at the nth position, where n is in the range [1, size()]. The case that we insert a new Node at the first position can be tanckled by the push_front function.

The graph below illustrate a 5-Node linked list and the case that we intend to insert the new Node at a non-Head position. For example, we insert at the third position, that is, when n == 3:

We can observe that:

<ol>

<li>the newly created Node becomes the third Node and the original third Node becomes the fourth Node.</li>

<li>before inserting <figure class="highlight plain"><table><tr><td class="gutter"><pre>1 </pre></td><td class="code"><pre>add2->next == add2 </pre></td></tr></table></figure>

after inserting <figure class="highlight plain"><table><tr><td class="gutter"><pre>1 </pre></td><td class="code"><pre>add2->next == addx </pre></td></tr></table></figure></li>

<li>to link following Nodes, we let <figure class="highlight plain"><table><tr><td class="gutter"><pre>1 </pre></td><td class="code"><pre>addx->next == add3 </pre></td></tr></table></figure>

Now everything is clear: if we want to insert at the nth position, we have to find the n-1 position and link the n-1th Node to the newly created Node. Let’s starting from the ptrToHead and show the relations between Nodes, Addresses and Iteration times:<figure class="highlight plain"><table><tr><td class="gutter"><pre>1 2 3 4 5 6 7 </pre></td><td class="code"><pre> counter i Address Node when i = 0 ptrToHead 1st Node i = 1 add2 2ed Node i = 2 add3 3ed Node ... ... ... i = n - 2 add(n - 1) n - 1 Node i = n - 1 addn n Node </pre></td></tr></table></figure>

</li>

</ol>

Obviously, we will stop our loop when i == n - 2 and by then we can manipulate the n - 1 Node. Following code shows a full view of the insert function.

<h2 id="pop-front-pop-back-erase"><a href="#pop-front-pop-back-erase" class="headerlink" title="pop_front, pop_back, erase"></a>pop_front, pop_back, erase</h2>The idea behind these three functions are similar to the inserting operations described above. Hence no further discussion here.

<figure class="highlight"><table><tr><td class="gutter"><pre>1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 </pre></td><td class="code"><pre>// delete at the begining: O(1) template <class T> void SinglyLinkedList<T>::pop_front(){ if(ptrToHead == nullptr){ throw std::domain_error("Empty Linked List"); } Node* temp = ptrToHead; ptrToHead = ptrToHead->next; delete temp; --count; } // delete the last element: O(n) template <class T> void SinglyLinkedList<T>::pop_back(){ if(ptrToHead == nullptr){ throw std::domain_error("Empty Linked List"); } erase(size()); } // delete at nth position: O(n) // n belongs to [1, size()], the position after n - 1 template <class T> void SinglyLinkedList<T>::erase(size_type position){ if(position < 1 || position > size()) throw std::domain_error("Invalid Position"); else if(position == 1) pop_front(); else{ Node* current = ptrToHead; for (size_type i = 0; i != position-2; ++i) current = current->next; Node* temp = current->next; current-> next = temp->next; delete temp; --count; } } ## remove // remove elements with specific values: O(n^2) template <class T> void SinglyLinkedList<T>::remove(const T& val){ Node* current = ptrToHead; size_type i = 0; while(current != nullptr){ if(current->data == val){ current = current->next; erase(i + 1); } else{ current = current->next; ++i; } } } The remove function allows us to remove all elements that contains data values equal to a supplied value. My solution is to find the positions of the Nodes that should be removed and then call the **erase** function by passing the position. Taking an example(see below graph), suppose one want to remove any element that has value **v3**, we should find the previous position, that is, **2ed Node**, and then break the link and rebuilt the link between **2ed Node** and **4th Node** through: </pre></td></tr></table></figure>

temp = add2->next temp = temp->next

<pre><code>counter i values position</code></pre>when i = 0 v1 1 i = 1 v2 2 i = 2 v3 3 … … … i = n - 2 v(n - 1) n - 1 i = n - 1 vn n

The basic idea behind the reverse function is that let each Node stores the address of the previous Node. The initial information is that:

<ol>

<li>the previous address for the Head Node is nullptr</li>

<li>the current address for the Head Node is ptrToHead</li>

</ol>

There are four steps in each iteration:

<ol>

<li>temporarily stores the address of next Node as next = current->next will be rewrite </li>

<li>rewrite the current->next with the previous address</li>

<li>in next iteration, the previous address is the current address in this iteration, hence let prev = current</li>

<li>in next iteration, the current address is the next address in this iteration, hence let current = next</li>

</ol>

The recursive version starts from the last Node but still uses the same idea. Don’t forget to add this function template as the friend of our SinglyLinkedList class.

<h2 id="Test"><a href="#Test" class="headerlink" title="Test"></a>Test</h2>I have tested every member in this class template and the results show that this SinglyLinkedList works perfectly. Please find the test program and results below:

<figure class="highlight c++"><table><tr><td class="gutter"><pre>1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 </pre></td><td class="code"><pre>/* * this program tests all operations that provided by the * SinglyLinkedList<T> class * created by Liam on: 28 Apr 2018 */ #include <iostream> #include "SinglyLinkedList.h" using std::endl; using std::cout; template <class T> void print(T& l){ auto it = l.begin(); for(; it != nullptr; it = it->next){ cout << it->data << " "; } cout << endl; } int main(){ { // construct an empty linked list SinglyLinkedList<int> s; if(s.empty()) cout << "s is an empty linked list\n" "the size of s1 is: " << s.size() << endl; // call destructor once reaches the end of this block } cout << endl; { // construct a linked list that contains 10 elements, all values are 100 SinglyLinkedList<int> s(10, 100); // construct a linked list by copying from s SinglyLinkedList<int> s_copy(s); if(!s.empty() && !s_copy.empty()){ cout << "the size of s is: " << s.size() << endl; cout << "the size of s_copy is: " << s_copy.size() << endl; } // print the contents of s cout << "all elements in s: "; print(s); // call destructor twice } cout << endl; { // assignment SinglyLinkedList<int> s(10, 100); SinglyLinkedList<int> s_copy; s_copy = s; // print the contents of s } cout << endl; { // push front SinglyLinkedList<double> s; for(int i = 5; i != 0; --i) s.push_front(i); cout << "after adding elements at front, s becomes: "; print(s); // push back for(int i = 5; i != 0; --i) s.push_back(i); cout << "after adding elements at the end, s becomes: "; print(s); // insert at position 5 for(int i = 5; i != 0; --i) s.insert(i, 0); cout << "after inserting elements in-between, s becomes: "; print(s); // delete from the begining for(int i = 5; i != 0; --i) s.pop_front(); cout << "after deleting from the begining, s becomes: "; print(s); // delete from the end for(int i = 5; i != 0; --i) s.pop_back(); cout << "after deleting from the end, s becomes: "; print(s); // erase at in-between positions for(int i = 3; i != 0; --i) s.erase(3); cout << "after deleting from other positions, s becomes: "; print(s); } cout << endl; { // remove SinglyLinkedList<int> s(5, 5); for(int i = 5; i != 0; --i) s.insert(5, i); cout << "at present, s contains following elements: "; print(s); s.remove(5); cout << "after removing all elements equal 5, s becomes: "; print(s); } cout << endl; { // test reverse function SinglyLinkedList<int> s; for(int i = 0; i != 10; ++i) s.push_back(i); cout << "at present, s contains following elements: "; print(s); s.reverse(); cout << "reverse: "; print(s); s.reverse(); cout << "reverse again: "; print(s); } return 0; } </pre></td></tr></table></figure>

Outputs:

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