c++中栈与队列的实现

1. 栈：具有先进后出的特点，且只能在一端进行插入与删除的操作，栈的实现如下所示
2. struct truetype
3. {
4. bool get()
5. {
6. return true;
7. }
8. };
9. struct falsetype
10. {
11. bool get()
12. {
13. return false;
14. }
15. };
16. template<class T>
17. struct typetraits
18. {
19. typedef falsetype  isnpodtype;
20. };
21. template <>
22. struct typetraits<int>
23. {
24. typedef truetype  ispodtype;
25. };
26. template<class T>
27. class stack
28. {
29. protected:
30. T *_a;
31. size_t _top;
32. size_t _capacity;
33. public:
34. stack()
35. : _top(0)
36. , _capacity(3)
37. {
38. _a = new T[_capacity];
39. }
40. ~stack()
41. {
42. if (_a)
43. delete[] _a;
44. }
45. void  checkcapacity()
46. {
47. if (_top == _capacity)
48. {
49. _capacity = 2 * _capacity;
50. T *tem = new T[_capacity];
51. if ((typetraits<T>::ispodtype()).get())
52. {
53. memcpy(tem, _a, sizeof(T)*_capacity);
54. delete[]_a;
55. _a = tem;
56. }
57. else
58. {
59. int i = 0;
60. for (i = 0; i < _top; i++)
61. {
62. tem[i] = _a[i];
63. }
64. delete[]_a;
65. _a = tem;
66. }
67. }
68. }
69. void push(const T&x)
70. {
71. checkcapacity();
72. _a[_top] = x;
73. _top++;
74. }
75. void pop()
76. {
77. _top--;
78. }
79. bool Empty()
80. {
81. return _top == 0;
82. }
83. T &Top()
84. {
85. if (_top > 0)
86. {
87. size_t ret = _top;
88. _top--;
89. return _a[ret - 1];
90. }
91. }
92. };
93. int main()
94. {
95. stack<int> s1;
96. s1.push(1);
97. s1.push(2);
98. s1.push(3);
99. s1.push(4);
100. while (!s1.Empty())
101. {
102. cout << s1.Top() << " ";
103. }
104. getchar();
105. return 0;
106. }

2.队列：具有队头插入，队尾删除的特点，具有一个头指针和一个尾指针

template <class T>

struct Node

{

T _data;

Node <T> *_next;

Node(const T &data=0)

{

_data = data;

_next = NULL;

}

};

template <class T>

class Queue

{

protected:

Node<T> *_head;

Node <T>*_tail;

public:

Queue()

:_head(NULL)

, _tail(NULL)

{}

~Queue()

{

Node<T> *ret = NULL;

if (_head == NULL)

return;

if (_head == _tail)

{

delete _head;

_head = NULL;

_tail = _head;

}

else

{

while (_head)

{

pop();

}

}

}

void push(const T&x)

{

Node<T> *newNode = new Node<T>(x);

if (_tail == NULL)

{

_tail = newNode;

_head = _tail;

}

else

{

_tail->_next = newNode;

_tail = newNode;

}

}

void pop()

{

Node<T>*ret = NULL;

if (_head == NULL)

return;

if (_head == _tail)

{

delete _head;

_head = NULL;

_tail = _head;

}

else

{

ret = _head;

_head = _head->_next;

delete ret;

}

}

T &Front()

{

Node <T>*ret = _head;

_head = _head->_next;

return ret->_data;

}

T &Back()

{

Node <T>*ret = _tail;

_tail = _head->_tail;

return _tail->_data;

}

bool Empty()

{

return _head == _tail;

}

void show()

{

while (_head)

{

cout << _head->_data << " ";

_head = _head->_next;

}

}

};

int main()

{

Queue<int> q;

q.push(1);

q.push(2);

q.push(3);

q.push(4);

q.pop();

q.show();

getchar();

return 0;

}