棧在實際程式設計中經常會用到，本文利用陣列和連結串列分別實現了棧的操作。

1.陣列方式實現如下：

#include<iostream>

using namespace std;

template <class T>
class arraystack{
public:
    arraystack();
    ~arraystack();
    bool isempty();
    void push(const T& data);
    void pop();
    T& gettop();

private:
    T *stacknodes;
    int top;
    int capacity;
};

template<class T>
arraystack<T>::arraystack()
{
    capacity=3;
    stacknodes=new T[3];
    top=-1;
    cout<<"the stack is constructed!"<<endl;
    cout<<"the capacity is:"<<capacity<<endl;
}

template <class T>
arraystack<T>::~arraystack()
{
    delete []stacknodes;
    capacity=0;
    top=-1;
    cout<<"the stack is destructed!"<<endl;
}


template <class T>
bool arraystack<T>::isempty()
{
    if(top==-1)
        return true;
    else
        return false;
}

template <class T>
void arraystack<T>::push(const T& data)
{
    if(top+1==capacity)
    {
        capacity=2*capacity;
        T *p=new T[capacity];
        for(int i=0;i<=top;++i)
            p[i]=stacknodes[i];
        T *q=stacknodes;
        stacknodes=p;
        delete []q;      
        cout<<"the capacity is:"<<capacity<<endl;
    }
    stacknodes[++top]=data;
    cout<<"push in:"<<stacknodes[top]<<endl;
}

template <class T>
void arraystack<T>::pop()
{
    if(!isempty())
        top--;
}

template <class T>
T& arraystack<T>::gettop()
{
    if(!isempty())
        return stacknodes[top];

}

int main()
{
    const int n=5;
    int data;
    arraystack<int> stk;
    int a[n]={4,8,6,12,9};
    for(int i=0;i<n;i++)
        stk.push(a[i]);

    while(!stk.isempty())
     {
         data=stk.gettop();
         cout<<"pop out:"<<data<<endl;
         stk.pop();
     }
}
 

#include<iostream>

using namespace std;

template <class T>
struct linknode{
    T data;
    linknode* next;
};

template <class T>
class mystack{
public:
    mystack();
    ~mystack();
    bool isempty();
    void push(const T& data);
    void pop();
    T& gettop();

private:
    linknode<T> *head;
    linknode<T> *top;
    int length;

};

template <class T>
mystack<T>::mystack()
{
    head=NULL;
    top=NULL;
    length=0;
    cout<<"the stack is constructed!"<<endl;
}

template <class T>
mystack<T>::~mystack()
{
    while(!isempty())
        pop();
    cout<<"the stack is destructed!"<<endl;
}

template <class T>
bool mystack<T>::isempty()
{
    if(head==NULL)
        return true;
    else
        return false;

}

template <class T>
void mystack<T>::push(const T& data)
{
    if(!head)
    {
        head=new linknode<T>;
        head->data=data;
        head->next=NULL;
        top=head;
        length++;
        cout<<"push in:"<<top->data<<endl;
    }
    else
    {
        linknode<T> *p=new linknode<T>;
        p->data=data;
        p->next=NULL;
        top->next=p;
        top=p;
        length++;
        cout<<"push in:"<<top->data<<endl;
    }
}

template <class T>
void mystack<T>::pop()
{
    if(!isempty())
    {
    linknode<T> *p=head;
    if(p==top)
    {
        head=NULL;
        top=NULL;
    }
    else
    {
        while(p->next!=top)
        {
            p=p->next;
        }
        top=p;
        p=top->next;
    }
    delete p;
    length--;
    }
}

template <class T>
T& mystack<T>::gettop()
{
    if(!isempty())
        return top->data;
}

int main()
{
    const int n=5;
    int data;
    mystack<int> stk;
    int a[n]={4,8,6,12,9};
    for(int i=0;i<n;i++)
        stk.push(a[i]);
    while(!stk.isempty())
     {
         data=stk.gettop();
         cout<<"pop out:"<<data<<endl;
         stk.pop();
     }
}