turn the struct to a class

cpp/includes/Example.hpp

@@ -3,14 +3,15 @@
 
 #include <iostream>
 
-struct Example {
+class Example {
+  friend std::ostream &operator<<(std::ostream &out, const Example &data);
+
+public:
   Example();          // constructor
   virtual ~Example(); // destructor
 
   Example(const Example &);                  // copy constructor
   const Example &operator=(const Example &); // copy assignement
-
-  friend std::ostream &operator<<(std::ostream &out, const Example &data);
 };
 
 #endif