1. By default, copying a class object is equivalent to copying all of its data members (shallow copy).
  2. By default, a class object is passed by value when specified as a function argument or as a function return value. 
     #include <iostream>
    
 class MyClass {
 public:
     MyClass(int v) : _member(v) {}
     int display() { return _member; }
     int& get() { return _member; }
 private:
     int _member;
 };
    
 void modifyObject( MyClass obj ){
    obj.get() = 3;
 }
    
 MyClass returnByValue(){
    MyClass obj(2);
    return obj;
 }
    
 int main() {
    
     MyClass obj(1);
     modifyObject(obj);
     std::cout << obj.display() << std::endl;
    
     MyClass obj2 = returnByValue();
     std::cout << obj2.display() << std::endl;
    
     return 0;
 }