#include <iostream>
#include <cstdlib>
#include <stack>   //for class stack
#include <string>  //for class string
using namespace std;

void stackOfInts();     //function declarations
void stackOfStructs();

int main()
{
	stackOfInts();
	cout << "\n";   //Skip a line.
	stackOfStructs();

	return EXIT_SUCCESS;
}

void stackOfInts()
{
	stack<int> s;   //Born empty, but capable of holding ints.
			//The full name of this data type is std::stack<int>

	s.push(10);
	s.push(20);
	s.push(30);

	cout << s.top() << "\n";  //Output the most recently pushed it.
	s.pop();                  //Remove the most recently pushed item.
	cout << s.top() << "\n";
	s.pop();
	cout << s.top() << "\n";
	s.pop();
}       //s is automatically destructed when we hit this closing curly brace.

void stackOfStructs()
{
	struct person {
		string firstname;
		string lastname;
	};

	const person a[] {         //an array of three structs
		{"George", "Washington"},
		{"John",   "Adams"},
		{"Thomas", "Jefferson"}
	};

	stack<person> s;           //Born empty, but capable of holding persons.

	for (const auto& p: a) {   //Push the 3 persons onto stack s.
		s.push(p);
	}

	while (!s.empty()) {       //Keep popping stack s until it's empty.
		const person p {s.top()};
		s.pop();
		cout << p.firstname << " " << p.lastname << "\n";
	}
}       //s is automatically destructed when we hit this closing curly brace.