Re: [Boost-users] [multi_array] How to use std algorithms, like for_each?

From: Antonio Piccolboni (piccolbo_at_[hidden])
Date: 2006-03-05 20:28:59

Use origin() if you you want to go straight to the element level, or
alternatively define a one-dimensional view of your liking and use begin()
(not clear from your code what you are trying to achieve,
but iVoxel = oVolume.origin() should do it). I hope this helps

Antonio

On 3/5/06, Christian Henning <chhenning_at_[hidden]> wrote:
>
> Hi there, I'm a little confused by the documentation of the
> multi_array lib. The begin() is supposed to return an iterator, but
> dereferencing doesn't resolve into the value type. This makes it a
> little complicated to use multi_arrays with standard algorithms.
> Please consider the following code snippet which wont compile on VC
> 7.1.
>
> class tVoxel
> {
> public:
>
>    typedef short tValue;
>
>    tVoxel(): _oValue( 0 ) {}
>    tVoxel(tValue oValue): _oValue( oValue ) {}
>
>    void set( const tValue& oValue ) { _oValue = oValue; }
>
>    tValue&       get()       { return _oValue; }
>    const tValue& get() const { return _oValue; }
>
> private:
>
>    tValue _oValue;
> };
>
> int _tmain(int argc, _TCHAR* argv[])
> {
>    typedef boost::multi_array<tVoxel, 3> tVolume;
>
>    tVolume oVolume( boost::extents[3][3][3] );
>
>    tVolume::const_iterator iVoxel    = oVolume.begin();
>    tVolume::const_iterator iVoxelEnd = oVolume.end();
>
>    const tVoxel& oVoxel = iVoxel->get();
>
>    return 0;
> }
>
> The error message goes like:
>
> error C2039: 'get' : is not a member of
> 'boost::detail::multi_array::const_sub_array<T,NumDims>'
>         with
>         [
>             T=tVoxel,
>             NumDims=2
>         ]
>
>
> Do I miss something important, here?
>
> Thanks for your help,
> Christian
>
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