1 #ifndef _QUEUELI_H
2 #define _QUEUELI_H
3
4 template<class Object>
5 class Queue
6 {
7
8 public:
9 Queue();
10 ~Queue();
11
12 bool isEmpty() const;
13 const Object & getFront() const;//返回队首数据
14 void enqueue(const Object & x);//在队尾加入数据
15 Object dequeue();//出队
16 void makeEmpty();
17 private:
18
19 //嵌套结构
20 struct ListNode
21 {
22
23 Object element;//元素
24 ListNode *next;//指针
25
26 ListNode(const Object & theElement,ListNode *n = 0)
27 :element(theElement), next(n){}
28
29 };
30
31 ListNode *front;
32 ListNode *back;
33
34 };
35
36 template <class Object>
37 Queue<Object>::Queue()
38 {
39
40 front = back =0;
41
42 }
43
44 template <class Object>
45 Queue<Object>::~Queue()
46 {
47
48 makeEmpty();
49
50 }
51
52 template <class Object>
53 void Queue<Object>::makeEmpty()
54 {
55
56 if(!isEmpty())
57 dequeue();
58 }
59
60 template<class Object>
61 bool Queue<Object>::isEmpty() const
62 {
63
64 return front == 0;
65
66 }
67
68 template <class Object>
69 const Object & Queue<Object>::getFront() const
70 {
71
72 if(isEmpty())
73 throw"Queue is empty";
74 return front->element;
75
76 }
77
78 template <class Object>
79 void Queue<Object>::enqueue(const Object &x)//入栈
80 {
81
82 if(isEmpty())
83 back = front = new ListNode(x);//节点里的数据是x,第二个参数用的是缺省值,指向下一个节点的指针为零。
84 else
85 back = back->next = new ListNode(x);
86
87
88 }
89
90 template<class Object>
91 Object Queue<Object>::dequeue()
92 {
93
94 Object frontItem = getFront();
95
96 ListNode *old = front;//声明一个指针old用来接住要被删除的front;
97
98 front = front ->next;
99 delete old;
100
101 return frontItem;
102
103
104 }
105 #endif