Re: [Boost-users] Boost.MultiArray + iterators

From: Dennis Zickefoose (dennis.zickefoose_at_[hidden])
Date: 2005-11-12 23:12:16

That worked great.  Thanks a million.

DZJr

Ronald Garcia wrote:
> Hi Dennis,
> 
> I don't have access to VC++ 7.1 at the moment and cannot recreate the  
> error you are seeing on my platform.  Could you try applying the  
> following patch to boost/multi_array/types.hpp and let me know if this  
> does the trick?
> 
> Thanks,
> ron
> 
> 
> *** types.hpp	01 Dec 2003 14:07:10 -0500	1.3
> --- types.hpp	12 Nov 2005 10:19:48 -0500	
> ***************
> *** 26,32 ****
> 
>    // needed typedefs
>    typedef std::size_t size_type;
> ! typedef int index;
> 
>    } // namespace multi_array
>    } // namespace detail
> --- 26,32 ----
> 
>    // needed typedefs
>    typedef std::size_t size_type;
> ! typedef std::ptrdiff_t index;
> 
>    } // namespace multi_array
>    } // namespace detail
> 
> 
> 
> On Nov 6, 2005, at 1:29 AM, Dennis Zickefoose wrote:
> 
>> I have a simple two dimensional multi_array that I am trying to copy a
>> row out of.  This works, but I get a warning about a type conversion
>> that I would like to get rid of.  Example:
>>
>> boost::multi_array<double, 2> array(boost::extents[42][42]);
>> std::vector<double> row(array[0].begin(), array[0].end());
>>
>> This produces the following warning in VC++ 7.1:
>> c:\Boost\include\boost-1_33\boost\multi_array\iterator.hpp(149) :
>> warning C4244: '+=' : conversion from
>> 'boost::detail::multi_array:: 
>> array_iterator<T,TPtr,NumDims,Reference>::difference_type'
>> to
>> 'boost::detail::multi_array:: 
>> array_iterator<T,TPtr,NumDims,Reference>::index',
>> possible loss of data
>>
>> This is followed by a long string of support messages that ultimately
>> point to the vector initialization.  Yet the vector is successfully
>> initialized with the range of values I expect.  So what am I doing  
>> wrong
>> here?  I understand that [array.begin(), array.end()) is actually a
>> range of sub-views, rather than a range of values...is this a side
>> effect of this distinction?
>>
>> At the moment, I have replaced that with &array[0][0] to avoid the
>> warning, but if possible I would like to go with the more reliable
>> iterator interface in the future.
>>
>> Any suggestions/advice would be greatly appreciated.
>>
>> DZJr
>>
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