进栈 出栈

#include "stdafx.h"
#include "iostream"

using namespace std;

class Stack
{
public:
virtual void push(char c) = 0;
virtual char pop() = 0;
};

class ArrayStack:public Stack
{
public:
ArrayStack(int s);
~ArrayStack();
void push(char c);
char pop();
private:
char* p;
int maxSize;
int top;
};

ArrayStack::ArrayStack(int s)
{
top = 0;
maxSize = s;
p = new char[s];
}

ArrayStack::~ArrayStack()
{
delete[] p;
}

void ArrayStack::push(char c)
{
if (top==maxSize)
{
cerr << "overflow ";
return;
}
p[top] = c;
top++;
}
char ArrayStack::pop()
{
if (top==0)
{
cerr << "underflow! ";
return '';
}
top--;
return p[top];
}
void f(Stack& sRef)
{
char ch[] = { 'a', 'b', 'c' };
cout << ch[0] << ',' << ch[1] << ',' << ch[2] << endl;
sRef.push(ch[0]);
sRef.push(ch[1]);
sRef.push(ch[2]);
cout << sRef.pop() << ",";
cout << sRef.pop() << ',';
cout << sRef.pop() << endl;
}
int _tmain()
{
ArrayStack as(10);
f(as);
return 0;
}