Re: Array of objects from class without default constructor

From:

SG <s.gesemann@gmail.com>

Newsgroups:

comp.lang.c++

Date:

Mon, 30 Mar 2009 07:27:06 -0700 (PDT)

Message-ID:

<74db2578-2dfd-49c4-ab8f-8c12fe766a5e@v19g2000yqn.googlegroups.com>

On 30 Mrz., 15:00, Matthias <oron...@gmail.com> wrote:

As far as I know, it's not possible to get an array new-expression
call a class constructor with parameters. Thus, it is non trivial
to build an array of object belonging to a class, say A, without
default constructor.
[...]
Are there other solutions to the `array of objects from class
without default constructor' problem?

Use a std::vector<A> and its push_back function. A vector's value
type only needs to be copy-constructible. push_back will copy-
construct the new element in the vector.

Altough this is not of help for you now it's IMHO still worth
mentioning: The future C++ version will replace the "copy
constructible" requirement with a "move constructible" requirement for
the value type. Also, it will be possible to directly create such an
object in the vector via std::vector::emplace_back =E0 la

std::vector<A> avec;
avec.emplace_back(5);

Side note: Consider making A::A(size_t) an explicit constructor.

Cheers!
SG