1 #include <iostream>
2
3 template <class T>
4 class List
5 {
6 struct Item
7 {
8 T data;
9 Item *next;
10 };
11
12 public:
13 List();
14 ~List();
15
16 bool isEmpty() const;
17 int length() const;
18 const T &at(int k) const;
19 int search(const T &v);
20 void remove(int k);
21 void insert(int k, const T &v);
22 void output();
23
24 private:
25 Item *header;
26 };
27
28 template <class T>
29 List<T>::List()
30 {
31 header = 0;
32 }
33
34 template <class T>
35 List<T>::~List()
36 {
37 Item *tmp, *i = header;
38 while (i)
39 {
40 tmp = i;
41 i = i->next;
42 delete tmp;
43 }
44 }
45
46 template <class T>
47 bool List<T>::isEmpty() const
48 {
49 return header == 0;
50 }
51
52 template <class T>
53 int List<T>::length() const
54 {
55 int len = 0;
56 Item *i = header;
57 while (i)
58 {
59 len++;
60 i = i->next;
61 }
62
63 return len;
64 }
65
66 template <class T>
67 const T &List<T>::at(int k) const
68 {
69 do
70 {
71 if (k < 0)
72 break;
73
74 Item *it = header;
75 if (it == 0)
76 break;
77
78 int i;
79 for (i = 0; it && i < k; i++)
80 it = it->next;
81
82 if (i != k)
83 break;
84
85 return it->data;
86 }
87 while (0);
88
89 T *ret = new T;
90 return *ret;
91 }
92
93 template <class T>
94 int List<T>::search(const T &v)
95 {
96 int k = 0;
97 Item *i = header;
98 while (i)
99 {
100 if (i->data == v)
101 return k;
102
103 k++;
104 i = i->next;
105 }
106
107 return -1;
108 }
109
110 template <class T>
111 void List<T>::remove(int k)
112 {
113 if (k < 0)
114 return;
115
116 Item *prev = 0, *it = header;
117 for (int i = 0; i < k; i++)
118 {
119 if (it == 0)
120 return;
121
122 prev = it;
123 it = it->next;
124 }
125
126 if (prev != 0)
127 prev->next = it->next;
128 else
129 header = it->next;
130
131 delete it;
132 return;
133 }
134
135 template <class T>
136 void List<T>::insert(int k, const T &v)
137 {
138 Item *t = new Item;
139 t->data = v;
140 t->next = 0;
141
142 if (header == 0)
143 {
144 header = t;
145 return;
146 }
147
148 Item *it = header;
149 bool flag = false;
150 if (k < 0)
151 flag = true;
152
153 for (int i = 0; it->next != 0 && (flag || i < k); i++)
154 it = it->next;
155
156 t->next = it->next;
157 it->next = t;
158 }
159
160 template <class T>
161 void List<T>::output()
162 {
163 Item *i = header;
164 while (i)
165 {
166 std::cout << i->data << std::endl;
167 i = i->next;
168 }
169 }
170
171 int main()
172 {
173 List<int> a;
174 std::cout << "a.isEmpty() " << a.isEmpty() << std::endl;
175
176 for (int i = 0; i < 10; i++)
177 a.insert(-1, i);
178
179 a.remove(0);
180 a.remove(7);
181 a.insert(5, 65535);
182
183 std::cout << "a.length() " << a.length() << std::endl;
184 std::cout << "a.at(3) " << a.at(3) << std::endl;
185 std::cout << "a.search(6) " << a.search(6) << std::endl;
186 std::cout << "a.search(100) " << a.search(100) << std::endl;
187 a.output();
188
189 return 0;
190 }
