Some Notes on C++ Constructors

1. The followings are automatically added to every class, if we do not write our own.

   • copy constructor
   • assignment operator
   • a constructor without without any parameter

2. A copy constructor may be called

   • when an object of the class is returned by value
   • when an object of the class is passed (to a function) by value as an argument
   • when an object is constructed based on another object of the same class
   • when compiler generate a temporary object

3. Unlike new, malloc() doesn't call constructor.

4. Object must be passed by reference in copy constructors.

5. We must use initializer list in a constructor when

   • there is a reference variable in class
   • there is a constant variable in class
   • there is an object of another class. And the other class doesn't have default constructor.

6. If a class has a constructor which can be called with a single argument, then this constructor becomes conversion constructor because such a constructor allows automatic conversion to the class being constructed. A conversion constructor can be called anywhere when the type of single argument is assigned to the object.

References: https://www.geeksforgeeks.org/c-plus-plus-gq/constructors-gq/