数据结构实验二-----入栈出栈基本操作（忘记初始化，而且没有读懂题意）

#include<iostream>
#include<string>
#include<cstring>
#define maxsize 1000
using namespace std;
typedef struct StackNode *LinkStack;
struct StackNode {
    int data;
    LinkStack next;
};
int flag;
int e;
void InitStack(LinkStack &s)
{
    s = NULL;
}
void Push(LinkStack &s, int e)
{
    LinkStack p = new StackNode;
    p->data = e;
    p->next = s;
    s = p;

}
void Pop(LinkStack &s, int &e)
{
    if (s == NULL)
    {
        flag = 0;
        cout << "POP ERROR" << endl;
        return;
    }
    else
    {
        LinkStack p = s;
        s = s->next;
        cout << p->data << endl;
        delete p;
    }
}

int main()
{
    int n;
    while (cin >> n && n!=0)
    {
        if (n < 0)
            continue;
        LinkStack s;
        InitStack(s);
        int a[maxsize];
        for (int i = 0; i < n; i++)
            cin >> a[i];
        for (int i = 0; i < n; i++)
        {
            flag = 1;
            if (a[i]!= -1)
            {
                Push(s, a[i]);
            }
            else
            {
                Pop(s, e);
                if (flag == 0)
                {
                    break;
                }
            }
        }
    }
    return 0;
}