Array initializer in C++

[Wu]

Hi there,

I was wondering whether there is a way to use array initializer syntax to
initialize a non-static array member in a class in C++. In particular, if
I have a class Foo:

class Foo {
double arr[2];
}

How can I use C-like array intializer syntax:

double arr[2] = {1,2}

for the class?

Any help is appreciated.

--Peter

[mlimber]

Re: Array initializer in C++

Wu wrote:[color=blue]
> Hi there,
>
> I was wondering whether there is a way to use array initializer syntax to
> initialize a non-static array member in a class in C++. In particular, if
> I have a class Foo:
>
> class Foo {
> double arr[2];
> }
>
> How can I use C-like array intializer syntax:
>
> double arr[2] = {1,2}
>
> for the class?
>
> Any help is appreciated.
>
> --Peter[/color]

You cannot use that syntax with non-static members unless the data is
public and there are no constructors. Of course, constructors are to be
preferred (cf. http://www.parashift.com/c++-faq-lite/ctors.html). Also,
arrays are evil
(http://www.parashift.com/c++-faq-lit...html#faq-34.1). See
this post for two similar methods for initializing std::vectors
instead:

http://groups.google.com/group/comp.lang.c++/msg/e2fe5982913d4414

Cheers! --M

[Wu]

Re: Array initializer in C++

Then basically I cannot have a non-static const array member in a class in C++? For example,

class Foo {
const double arr[2];
}

A 'const' array has to be intialized using initializer and a 'const'
non-static member requires a class to have a constructor. And then with
the information you gave, you really cannot have a non-static const
array member in a class in C++.

Is this right? Thanks!

On Wed, 14 Dec 2005, mlimber wrote:
[color=blue]
> Wu wrote:[color=green]
> > Hi there,
> >
> > I was wondering whether there is a way to use array initializer syntax to
> > initialize a non-static array member in a class in C++. In particular, if
> > I have a class Foo:
> >
> > class Foo {
> > double arr[2];
> > }
> >
> > How can I use C-like array intializer syntax:
> >
> > double arr[2] = {1,2}
> >
> > for the class?
> >
> > Any help is appreciated.
> >
> > --Peter[/color]
>
> You cannot use that syntax with non-static members unless the data is
> public and there are no constructors. Of course, constructors are to be
> preferred (cf. http://www.parashift.com/c++-faq-lite/ctors.html). Also,
> arrays are evil
> (http://www.parashift.com/c++-faq-lit...html#faq-34.1). See
> this post for two similar methods for initializing std::vectors
> instead:
>
> http://groups.google.com/group/comp....fe5982913d4414
>
> Cheers! --M
>
>[/color]

[mlimber]

Re: Array initializer in C++

Wu wrote:[color=blue]
> On Wed, 14 Dec 2005, mlimber wrote:
>[color=green]
> > Wu wrote:[color=darkred]
> > > Hi there,
> > >
> > > I was wondering whether there is a way to use array initializer syntax to
> > > initialize a non-static array member in a class in C++. In particular, if
> > > I have a class Foo:
> > >
> > > class Foo {
> > > double arr[2];
> > > }
> > >
> > > How can I use C-like array intializer syntax:
> > >
> > > double arr[2] = {1,2}
> > >
> > > for the class?
> > >
> > > Any help is appreciated.
> > >
> > > --Peter[/color]
> >
> > You cannot use that syntax with non-static members unless the data is
> > public and there are no constructors. Of course, constructors are to be
> > preferred (cf. http://www.parashift.com/c++-faq-lite/ctors.html). Also,
> > arrays are evil
> > (http://www.parashift.com/c++-faq-lit...html#faq-34.1). See
> > this post for two similar methods for initializing std::vectors
> > instead:
> >
> > http://groups.google.com/group/comp....fe5982913d4414
> >
> > Cheers! --M
> >
> >[/color]
> Then basically I cannot have a non-static const array member in a class in C++? For example,
>
> class Foo {
> const double arr[2];
> }
>
> A 'const' array has to be intialized using initializer and a 'const'
> non-static member requires a class to have a constructor. And then with
> the information you gave, you really cannot have a non-static const
> array member in a class in C++.
>
> Is this right? Thanks!
>[/color]

Please put your response below the text you are responding to.
Top-posting is considered impolite. (I fixed it here.)

You are correct that you cannot do that innately. You could, however,
get around the limitation by using a const std::vector as in my
previously cited post or by using a boost::scoped_a rray and the
appropriate initializer like that given in the previously cited post.

Cheers! --M

[Victor Bazarov]

Re: Array initializer in C++

Wu wrote:[color=blue]
> Then basically I cannot have a non-static const array member in a class in C++? For example,
>
> class Foo {
> const double arr[2];
> }
>
> A 'const' array has to be intialized using initializer and a 'const'
> non-static member requires a class to have a constructor. And then with
> the information you gave, you really cannot have a non-static const
> array member in a class in C++.
>
> Is this right?[/color]

(a) Don't top-post.

(b) Yes, this is right.

V

[Wu]

Re: Array initializer in C++


mlimber wrote:
[color=blue]
> Wu wrote:[color=green]
> > On Wed, 14 Dec 2005, mlimber wrote:
> >[color=darkred]
> > > Wu wrote:
> > > > Hi there,
> > > >
> > > > I was wondering whether there is a way to use array initializer syntax to
> > > > initialize a non-static array member in a class in C++. In particular, if
> > > > I have a class Foo:
> > > >
> > > > class Foo {
> > > > double arr[2];
> > > > }
> > > >
> > > > How can I use C-like array intializer syntax:
> > > >
> > > > double arr[2] = {1,2}
> > > >
> > > > for the class?
> > > >
> > > > Any help is appreciated.
> > > >
> > > > --Peter
> > >
> > > You cannot use that syntax with non-static members unless the data is
> > > public and there are no constructors. Of course, constructors are to be
> > > preferred (cf. http://www.parashift.com/c++-faq-lite/ctors.html). Also,
> > > arrays are evil
> > > (http://www.parashift.com/c++-faq-lit...html#faq-34.1). See
> > > this post for two similar methods for initializing std::vectors
> > > instead:
> > >
> > > http://groups.google.com/group/comp....fe5982913d4414
> > >
> > > Cheers! --M
> > >
> > >[/color]
> > Then basically I cannot have a non-static const array member in a class in C++? For example,
> >
> > class Foo {
> > const double arr[2];
> > }
> >
> > A 'const' array has to be intialized using initializer and a 'const'
> > non-static member requires a class to have a constructor. And then with
> > the information you gave, you really cannot have a non-static const
> > array member in a class in C++.
> >
> > Is this right? Thanks!
> >[/color]
>
> Please put your response below the text you are responding to.
> Top-posting is considered impolite. (I fixed it here.)
>
> You are correct that you cannot do that innately. You could, however,
> get around the limitation by using a const std::vector as in my
> previously cited post or by using a boost::scoped_a rray and the
> appropriate initializer like that given in the previously cited post.
>
> Cheers! --M[/color]

Hi mlimber, Victor and all,

Sorry for the top-posting. I didn't mean it (I am new to newsgroup, so I
didn't know this convention).

Thanks a lot for your quick responses!

--Peter