🚀 go-pugleaf

jamshid@io.com (Jamshid Afshar) writes:

>James Kanze <kanze@lts.sel.alcatel.de> wrote:
>>Expressions of the form `int()' have always been allowed.  A (fairly)
>>recent change to the draft standard states that they have the same
>>value as default static initialization (in this case, 0).  The earlier
>>rules had the initailization undefined.
>
>Is the following legal?
>
>	class Foo {
>	   int x;
>	public:
>	   Foo()
>	     : x()   // legal?
>	   {}
>	};

Yes.

>and if so is it different than just:
>
>	Foo::Foo() {}

Yes, they are different.  The former is equivalent to

	Foo::Foo() : x(0) {}

This can be deduced from the following sections of the working paper:

	[class.base.init] 12.6.2/3
		"if the *expression-list* of the *mem-initializer* is
		omitted, the base class or member subobject is
		default-initialized (see [dcl.init])"

	[dcl.init] 8.5/5
		"To default-initialize an object of type T means:
		--if T is a non-POD class type ...;
		--if T is an array type ...;
		--otherwise, the storage for the object is zero-initialized."

--
Fergus Henderson             	WWW: http://www.cs.mu.oz.au/~fjh
fjh@cs.mu.oz.au              	PGP: finger fjh@128.250.37.3
---
[ To submit articles: try just posting with your news-reader.
                      If that fails, use mailto:std-c++@ncar.ucar.edu
  FAQ:      http://reality.sgi.com/employees/austern_mti/std-c++/faq.html
  Policy:   http://reality.sgi.com/employees/austern_mti/std-c++/policy.html
  Comments? mailto:std-c++-request@ncar.ucar.edu.
]