value & default initialization, and copy initialization

From:
Taras_96 <taras.di@gmail.com>
Newsgroups:
comp.lang.c++
Date:
Wed, 28 Oct 2009 22:43:15 -0700 (PDT)
Message-ID:
<417583eb-e074-44c8-b3f1-83a58f750136@2g2000prl.googlegroups.com>
Hi all,

I was hoping to run my understanding of the concepts in the subject
line past the news group. Given the class:

class Foo
{
    public:
        Foo(int);
        Foo();
        Foo (Foo const &);
};

Using the excerpts from the standard:

=93If 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
nonstatic object, the object and its subobjects, if any, have an
indeterminate initial value"

and:

"An object whose initializer is an empty set of parentheses, i.e., (),
shall be value-initialized."

Is the following correct?

Foo foo; // default initialised
Foo foo(); // value initialised
Foo foo = Foo(); // temporary Foo is value initialised, then foo is
copy-initialized with temporary. Note that compiler may optimise away
copy, but it DOES require Foo to be copy constructible. ie: it is
equiv to Foo foo(Foo());

int x; // unitialized
int x = int(); // temporary is value initialised, then x is copy-
initialized with temporary. Note that compiler may optimise away copy

Foo* pfoo = new Foo; // a Foo object is default initialised, and then
the pfoo pointer is copy initialized with the return value of the new
operator
Foo* pfoo = new Foo(); // a Foo object is value initialised, and then
the pfoo pointer is copy initialized with the return value of the new
operator

int* pInt = new int(); // an int is value initialised, and then the
pInt pointer is copy initialized with the return value of the new
operator
int* pInt = new int; // an int is uninitialised, and then the pInt
pointer is copy initialized with the return value of the new operator.
*pInt is indeterminate

Foo foo = 5; // equivalent to Foo foo = Foo(5); temporary Foo object
constructed, and then foo is copy initialized with temporary. Note
that the compiler may optimize away the copy
which of course is the same as
Foo foo(Foo(5));

Cheers!

Taras

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