> Paragraph 7 I'm using n3242. I can't seem to download http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2011/n3290.pdf If no initializer is specified for an object, and the object is of (possibly cv-qualified) non-POD class type (or array thereof), the object shall be default-initialized; if the object is of const-qualified type, the underlying class type shall have a user-declared default constructor. Otherwise, if no initializer is specified for a non-static object, the object and its subobjects, if any, have an indeterminate initial value); if the object or any of its subobjects are of const-qualified type, the program is ill-formed. I'm going to break the above down like a lawyer: 1) If no initializer is specified for an object, and the object is of (possibly cv-qualified) non-POD class type (or array thereof), the object shall be default-initialized; So Ray2() calls Ray(). 2) The implicitly-defined default constructor performs the set of initializations of the class that would be performed by a user-written default constructor for that class with no ctor-initializer (12.6.2) and an empty compound-statement. So if Ray() is commented out. It's the same as: Ray(){} 3) If no initializer is specified for an object, the object is default-initialized So n and u are "default-initialized" 4) To default-initialize an object of type T means: - if T is a (possibly cv-qualified) class type (Clause 9), the default constructor for T is called (and the initialization is ill-formed if T has no accessible default constructor); - if T is an array type, each element is default-initialized; - otherwise, no initialization is performed. So I would expect the 3rd case here " no initialization is performed" for n and u. I think I've got this now, but it was a big unclear at first. Are we on the same page now? Chris
