Re: inline assignment of vectors

From:
James Kanze <james.kanze@gmail.com>
Newsgroups:
comp.lang.c++
Date:
Sat, 18 Sep 2010 02:13:26 -0700 (PDT)
Message-ID:
<e6e449b4-a748-483c-a414-f1b09b640c3e@v23g2000vbi.googlegroups.com>
On Sep 16, 12:47 pm, =C1ngel Jos=E9 Riesgo <ajrie...@gmail.com> wrote:

On Sep 14, 3:16 pm, foice <franceschini.robe...@gmail.com> wrote:

why can't I make the same inline assignment for vectors?
float fp_values[] = { 0.1, 0.2 , 0.3, 0.4};

as for instance this
vector<float> v=(1.2, 3.3, 4.);


As others have mentioned, you can do that sort of thing in the
forthcoming C++ standard (C++0x). The correct syntax will be:

std::vector<float> v = {1.2f, 3.3f, 4.f};

I think the latest version of the GCC compiler already supports this
if you enable the experimental C++0x features.

any idea how to do that in one line and for arbitrary lenght of the
initialization?


In the current C++ standard (C++03), you can't do this in one line.
But if you can live with doing it in three lines, this is the way I do
it:

const float kVArray[] = {1.2f, 3.3f, 4.f};

const size_t kVArraySize = sizeof(kVArray) / sizeof(*kVArray);

std::vector<float> v(kVArray, kVArray + kVArraySize);


It's usual to define the template functions begin and end, so
you can write:

    float const kvArray[] = { 1.2f, 3.3f, 4.f };
    std::vector<float> v( begin( kvArray ), end( kvArray ) );

--
James Kanze

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