// Demonstrate constructors and destructors
// George F. Riley, ECE2036, Georgia Tech, Fall 2012

#include <iostream>

using namespace std;

class A 
{
public:
  // Define three constructors
  A();
  A(int a0);
  A(const A& a0);
  // Define the destructor
  ~A();
  
public:
  int a; // Member variable
};

// Default Constructor
A::A()
  : a(0)
{
  cout << "Default constructor, a = " << a << endl;
}

// Non-Default Constructor
A::A(int a0)
  : a(a0)
{
  cout << "Int constructor, a = " << a << endl;
}

// Copy Constructor
A::A(const A& a0)
  : a(a0.a)
{
  cout << "Copy constructor, a = " << a << endl;
}

// Destructor
A::~A()
{
  cout << "Destructor, a = " << a << endl;
}

  
  
// Define some global variables of class A
A ga1;
A ga2(2);
A ga3(ga2);  // This compiles, but is not a good idea. Why?

// Subroutine with no arguments
void sub1()
{
  cout << "Entering sub1" << endl;
  A sub1a;
  A sub1a2(2);
  A sub1a3(sub1a2);
  cout << "Exiting sub1" << endl;
}

// Subroutine with object A passed by value
void sub2(A a)
{
  cout << "Entering sub2" << endl;
  A sub2a(a);
  cout << "Exiting sub2" << endl;
}

// Subroutine with object A passed by address
void sub3(A* a)
{
  cout << "Entering sub3" << endl;
  A sub2a(3);
  cout << "Exiting sub3" << endl;
}

int main()
{
  cout << "Entering main" << endl;
  A a0;
  A a1(a0);
  A a2(2);
  A a3(3);
  A a4 = a2; // What about this one?
  cout << "Calling sub1" << endl;
  sub1();
  cout << "Back from sub1" << endl;
  cout << "Calling sub2" << endl;
  sub2(a3);
  cout << "Back from sub2" << endl;
  cout << "Calling sub3" << endl;
  sub3(&a2);
  cout << "Back from sub3" << endl;
  cout << "Exiting main" << endl;
}