C++ own Stack of objects. What is copied at push()? - c++

Question

Well, i implemented a FIFO stack (push,pop) stack in a Class with mem allocated ints.
So i asked to myself: if "int" is a datatype, why i cannot push "ADTs" to my own stack.
Then i came with this code:
#include <iostream>
class Person {
std::string name;
int age;
public:
Person(std::string pName = "", int pAge = 1)
{
name = pName;
age = pAge;
}
void Print()
{
std::cout << name << " " << age << std::endl;
}
};
class Stack {
Person * stack;
int size, top;
int index;
public:
Stack(int stackSize)
{
top = stackSize -1;
index = top;
stack = new Person[stackSize];
}
void push(Person person)
{
if (index < 0)
std::cout << "Stack UNDERFLOW" << "Index is: " << index << std::endl;
stack[index--] = person;
}
Person & pop()
{
if (index > top)
{
std::cout << "Stack OVERFLOW" << std::endl;
}
return stack[++index];
}
};
I know, there are stacks, queues, vectos, etc in the STL lib. I just wanted to do it by myself.
I want the stack push a copy of the object.
I'm not sure i don't know if the compiler is pushing addresses, copying the whole object (what is what i want) or what.
Please enlight me.
Here is my main() code:
int main()
{
Stack stack(100);
Person person("Lucas", 39);
for (int i = 0; i < 100; i++)
{
stack.push(person);
((Person)stack.pop()).Print();
}
return EXIT_SUCCESS;
}

Answer 1

To answer your question about copies, this:
stack[index--] = person;
makes a copy, because the type on both sides of the assignment is of type T.
This:
stack.push(person);
also makes a copy, because you are passing person by value. To avoid this (redundant) copy, declare push as:
void push(const T &person)

Answer 2

Well, what i did to solve my question was what #PaulMcKenzie said in his comment.
I created a template for the "Stack" class and any template "T" is the datatype that is passed to the this class.
About the main methond (in my question) it had an unnecesary cast to (Person) since it's implied.
Edit 2:
#Paul Sanders were right too, i was doing a redundant copy at push()
This way i solved my problem:
#include <iostream>
class Person {
std::string name;
int age;
public:
Person(std::string pName = "", int pAge = 1)
{
name = pName;
age = pAge;
}
void Print()
{
std::cout << name << " " << age << std::endl;
}
};
template <class T>
class Stack {
T * stack;
int size, top;
int index;
public:
Stack(int stackSize)
{
top = stackSize -1;
index = top;
stack = new T[stackSize];
}
void push(const T &person)
{
if (index < 0)
std::cout << "Stack UNDERFLOW" << std::endl;
stack[index--] = person;
}
T pop()
{
if (index > top)
{
std::cout << "Stack OVERFLOW" << std::endl;
}
return stack[++index];
}
};
int main()
{
Stack<Person> stack(100);
Person person1("Lucas", 39);
Person person2("Gustavo", 38);
for (int i = 0; i < 100; i++)
{
if (i % 2 == 0)
stack.push(person1);
else
stack.push(person2);
}
for (int i = 0; i < 100; i++)
stack.pop().Print();
return EXIT_SUCCESS;
}
In the example of the main() function, it creates an stack of Person objects of 100. Then i create 2 people: "Lucas" and "Gustavo" and push it intercalated to the my stack for 100 times (the first for statment).
Then the second and final for statement pop() all values and print them.