不使用库实现栈的基本操作

template<typenameT>

classStack

{

public:

                Stack()

                                :_a(NULL)

                                , _size(0)

                                , _capacity(0)

                {  }

                voidPush(constT&x)//相当于数组的尾插

                {

                                _CheckCapacity();

                                _a[_size++] =x;

                }

                voidPop()//移去栈顶元素,栈顶指向数组的最后一个数据

                {

                                if(_size != 0)

                                {

                                                _size--;

                                }

                }

                T& Top()//返回栈顶元素，即数组的最后一个元素

                {

                                return_a[_size-1];

                }

                boolEmpty() //如果栈为空，则返回true，否则，返回false

                {

                                if(_size == 0)

                                {

                                                returntrue;

                                }

                                else

                                {

                                                returnfalse;

                                }

                }

                size_tSize() //返回栈中元素数目

                {

                                return_size;

                }

                void_CheckCapacity()

                {

                                if(_size == _capacity)

                                {

                                         T* temp =newT[_capacity * 2 + 3];

                                   for(intindex = 0; index < _size; ++index)

                                                {

                                                                temp[index] = _a[index];

                                                }

                                                delete[] _a;

                                                _a = temp;

                                                _capacity = _capacity * 2 + 3;

                                }

                }

protected:

                T*   _a;

                size_t_size;

                size_t_capacity;

};

intmain()

{

                Stack<int> s;

                s.Push(3);

                s.Push(2);

                s.Push(1);

                //s.Pop();

                //s.Empty();

                intret=s.Top();

                cout << ret << endl;

                system("pause");

                return0;

}