按照《数据结构与算法（张铭编著）》课本要求敲的👇

#include<iostream>
using namespace std;
class arrstack
{
private:
	int size;
	int top;
	char* st;
public:
	arrstack(int csize)
	{
		size = csize;
		top = -1;
		st = new char(size);
	}
	arrstack()
	{
		top = -1;
	}
	~arrstack()
	{
		delete[]st;
	}
	void clear();
	bool push(char& a);
	bool pop(char& a);
	bool ctop(char& a);
};
void arrstack::clear()
{
	top = -1;
}
bool arrstack::push(char& a)
{
	if (top == (size - 1))
	{
		/*cout << "stack is already full." << endl;
		return false;*/
		char* newst = new char(2 * size);
		for (int i = 0; i < size; i++)
		{
			newst[i] = st[i];
		}
		delete st;
		st = newst;
		size *= 2;
	}
	st[++top] = a;
	return true;
}
bool arrstack::pop(char& a)
{
	if (top == -1)
	{
		cout << "stack is already empty." << endl;
		return false;
	}
	a = st[top--];
	return true;
}
bool arrstack::ctop(char& a)
{
	if (top == -1)
	{
		cout << "stack is already empty." << endl;
		return false;
	}
	else
	{
		a = st[top];
		return true;
	}
}