Passing references to objects : reference parameter « Function « C++ Tutorial

1. C++ Tutorial
2. Function
3. reference parameter

#include <iostream>
 
 class MyClass
 {
 public:
     MyClass();
     MyClass(MyClass&);
     ~MyClass();
 
     int GetAge() const { return itsAge; }
     void SetAge(int age) { itsAge = age; }
 
 private:
     int itsAge;
 };
 
 MyClass::MyClass()
 {
     std::cout << "Simple Cat Constructor...\n";
     itsAge = 1;
 }
 
 MyClass::MyClass(MyClass&)
 {
     std::cout << "Simple Cat Copy Constructor...\n";
 }
 
 MyClass::~MyClass()
 {
     std::cout << "Simple Cat Destructor...\n";
 }
 
 const MyClass & f (const MyClass & obj);
 
 int main()
 {
     MyClass myObject;
     std::cout << "myObject is " << myObject.GetAge() << " years old\n";
 
     int age = 5;
     myObject.SetAge(age);
     std::cout << "myObject is " << myObject.GetAge() << " years old\n";
 
     std::cout << "Calling f...\n";
     f(myObject);
     std::cout << "myObject is " << myObject.GetAge() << " years old\n";
     return 0;
 }
 
 const MyClass & f (const MyClass & obj)
 {
     std::cout << "Function Two. Returning...\n";
     std::cout << "myObject is now " << obj.GetAge()<< " years old \n";
     return obj;
 }

Simple Cat Constructor...
myObject is 1 years old
myObject is 5 years old
Calling f...
Function Two. Returning...
myObject is now 5 years old
myObject is 5 years old
Simple Cat Destructor...