Is always the default constructor for Fred Fred::Fred()?

A: No. A "default constructor" is a constructor which can be called with no arguments. One instance of this is a constructor that takes no parameters:

class Fred {            

public:

Fred(); // Default constructor: can be called with no args

...

};

Another instance of a "default constructor" is one which can take arguments, provided they are given default values:

class Fred {

public:

Fred(int i=3, int j=5); // Default constructor: can be called with no args

...

};