如何使用方法覆盖在输出屏幕上显示堆栈整数值

最近，我的实验室讲师通过使用方法重写的概念(我们目前正在研究继承(，给了我以下要运行的堆栈代码：

//4.3. This example demonstrates that how we can use the concept of Overriding.
#include<iostream>
#include<conio.h>
using namespace std;
class myStack {
protected:  //NOTE: Can't be private because only my child class should have access to it
enum {
maximumnumberofboxes = 3 
}; // enumerated is used before a user defined variable (maximumnumberofboxes) that contains a collection of built in datatypes. 
//I have used it to tell the size of my stack array
int stack[maximumnumberofboxes]; // my stack array of integers
int topvalue;
//Index to top of stack. An index accesses a specific element in my stack array (in this case, the top value)
public:
Stack() //my stack constructor
{
topvalue = -1;  
}
void push(int valueinbox) //Define a function that pushes the value of a specific element in the stack space
{
stack[++topvalue] = valueinbox; //put the value on stack
}
int pop()  //Define a function that pulls off the value of a specific element in the stack space
{
return stack[topvalue--]; //take number off stack
}
};

class childStack : public myStack //Single Inheritance
{
public:
void push(int valueinbox)
{ //put the value on stack
if(topvalue >= maximumnumberofboxes-1) //error if stack full
{
cout<<"topvalue = "<<valueinbox;
cout<<"ntopvalue= "<<topvalue;
cout << "nError: stack is full";
exit(1);
}
cout<<"ntopvalue= "<<topvalue;
cout<<"ntopindex= "<<valueinbox;
myStack::push(valueinbox); //call push() function in myStack class using unary scope operator
}
int pop() //call pop() function to pull value off my stack
{
if(topvalue < 0) //shows error if my stack is empty
{ 
cout << "nError: stack is emptyn";
exit(1);
}
return myStack::pop(); //call pop() in myStack class
}
};
int main()
{
childStack s1;
s1.push(11); //push some values onto child stack
s1.push(22);
s1.push(33);
cout << endl << s1.pop(); //pop some values from child stack
cout << endl << s1.pop();
cout << endl << s1.pop();
cout << endl << s1.pop(); //oops, popped one too many...
cout << endl;
system("pause");
getch();
return 0;
}

我的输出屏幕显示以下内容：

topvalue=11
topvalue=4249067
Error: stack is full

我想知道如何在输出屏幕上显示主函数(11,22,33(中提到的三个整数，而不会得到任何垃圾值？