#include <iostream>
using namespace std;

class CStack
{
private:
    char *s; //栈的内容保存在s中
    int tp;		//栈顶指示器，栈空为－1
    int size;
public:
    CStack(int initSize = 5);
    CStack(const CStack &scopy);
    CStack operator=(const CStack &scopy);
    ~CStack();
    bool isEmpty();
    bool isFull();
    void push(char c);
    char pop();
    char top();
};

CStack CStack::operator=(const CStack &scopy)
{
    if (this == &scopy) return *this;
    if(s!=NULL) free(s);
    size = scopy.size;
    tp = scopy.tp;
    s = NULL;
    if (size!=0)
    {
        s = new char[size];
        for (int i=0; i<=tp; i++)
            s[i] = scopy.s[i];
    }
    return *this;
 }

bool CStack::isEmpty()
{
    return (tp==-1);
}

bool CStack::isFull()
{
    return (tp==(size-1));
}

void CStack::push(char c)
{
    if (isFull())
    {
        char *p = new char[2*size];
        for (int i=0; i<size; i++)
            p[i] = s[i];
        delete []s;
        s = p;
        size = 2*size;
    }
    tp++;
    s[tp] = c;
}

char CStack::pop()
{
    int oldtp = tp;
    tp--;
    return s[oldtp];
}

char CStack::top()
{
    return s[tp];
}

CStack::CStack(int initSize)
{
    tp = -1;
    size = initSize;
    s = new char[size];
}

CStack::CStack(const CStack &scopy)
{
    tp = scopy.tp;
    size = scopy.size;
    if (size!=0)
    {
        s = new char [size];
        for (int i=0; i<=tp; i++)
            s[i] = scopy.s[i];
    }
}

CStack::~CStack()
{
    if (s!=NULL)
    {
        delete []s;
        s = NULL;
    }
}

int main()
{
    CStack s;

    for(int i=0; i<7; i++) s.push('a'+i);

    CStack sCopy;
    sCopy = s;

    while(!s.isEmpty()) cout << s.pop();
    cout << endl;

   for(int i=0; i<7; i++) s.push('1'+i);

    while(!sCopy.isEmpty()) cout<<sCopy.pop();
    cout<<endl;

    return 0;
}