如何阻止溢出？

Question

在受到我的实验室教练的启发后，我做了这件小事。我的程序可以很好地完成弹出，但是在最后的推动下它失败了。该值在超过阵列阈值后消失。有没有办法阻止它？

我们将不胜感激。谢谢:)）

此外，由于必须使用3个全局变量，我现在正在面对自己。正确方向的某些方面会有所帮助。

#include<iostream>
#include<cstdlib>
#include<conio.h>
using namespace std;
int n, *stack, *slack;
class stacks
{
int position;

public:

stacks()
{
    stack = new int[n];
    slack = new int[n];
    for(int i=0;i<n;i++)
    stack[i]='\0';
    position = 0;
}

void insert()
{
    push();
    position--;
    system("cls");
    cout<<"Enter the number to be added: ";
    cin>>stack[0];
    position++;
}

void push()
{
    system("cls");
    cout<<"The stack has been pushed";
    slack[0]=0;
    for(int j=0; j<n-1;j++)
    {
         slack[j+1]=stack[j];
    }
    for(int j=0; j<n;j++)
    {
         stack[j] = slack[j];
    }
    position++;
    stack[0] = 0;
}

void pop()
{   system("cls");
    int i=0;
    if(position<1)
    {
        cout<<"Underflow!";
        return;
    }
    cout<<"The number has been successfully popped from the stack!";    
    while(stack[i] != '\0')
    {
        stack[i]=slack[i];
        i++;
    }
    for(int j = 0 ; j<i ; j++)
    {
        stack[j]=stack[j+1];
    }
    stack[i] = '\0';
    position--;
}

void memusage()
{
    system("cls");
    cout<<"The total memory usage is: "<<position+1<<"/"<<n<<" .";
}

void display()
{

    for(int j = 0 ; j<n ; j++)
    {
        cout<<j+1<<" Member is: "<<stack[j]<<endl;
    }
}

};

int main()
{

cout<<"Enter the number of elements: ";
cin>>n;
stacks a;
char ac = 'y', b;
while( ac == 'y' || ac =='Y' || ac =='\n')
{
    system("cls");
    a.display();
    cout<<"\n\n\n";
    cout<<"Enter a new value [1]"<<endl;
    cout<<"Push the stack    [2]"<<endl;
    cout<<"Pop the stack     [3]"<<endl;
    cout<<"See memory usage  [4]"<<endl;
    cout<<"\n\nEnter your choice[1,2,3,4]: ";
    b=getch();
    if(b=='1')
    {a.insert();}
    else if(b=='2')
    {a.push();}
    else if(b=='3')
    {a.pop();}
    else if(b=='4')
    {a.memusage();}
    else cout<<"\nInvalid Entry. Please choose a valid entry!\n";

    cout<<"\n\nAnother?[y/Y]";
    ac=getch();
}
}