Re: [Boost-users] [Boost.MultiArray]: size question

Subject: Re: [Boost-users] [Boost.MultiArray]: size question
From: Vitaly Budovski (vbudovski+news_at_[hidden])
Date: 2012-12-17 19:44:29

On 18 December 2012 08:24, gast128 <gast128_at_[hidden]> wrote:
> I am talking about multi_array, see title. Example code:
>
> void f()
> {
>    typedef boost::multi_array<int, 2> Matrix;
>
>    Matrix m1(boost::extents[2][3]);
>    _ASSERT(m1.size()    == 2);
>    _ASSERT(m1[0].size() == 3);
>
>    m1.resize(boost::extents[0][3]);
>    _ASSERT(m1.size()    == 0);
>    //_ASSERT(m1[0].size() == 3);  //<--assert
> }
>
>

Hi,

The shape function has the list of multi_array dimensions.
This should do it:

#include <boost/multi_array.hpp>
#include <cassert>

int main()
{
    typedef boost::multi_array<int, 2> Matrix;

    Matrix m1(boost::extents[2][3]);
    assert(m1.shape()[0] == 2);
    assert(m1.shape()[1] == 3);

    m1.resize(boost::extents[0][3]);
    assert(m1.shape()[0] == 0);
    assert(m1.shape()[1] == 3);

    return 0;
}

Cheers,

Vitaly