[Boost-users] [iterator]counting_iterator question

From: Sean Huang (huangsean_at_[hidden])
Date: 2006-07-17 18:05:49

I encountered some problems while using counting_iterator. Suppose we have a 
range called RangeType, and we define:
    typedef boost::counting_iterator< boost::range_value< RangeType >::type 
 > MyCountingIterator;

if  I do:
    std::vector< int > vec( 100 );
    std::vector< int >:: iterator iter = vec.begin() + ( countingIter2 - 
counitingIter1 );

VC8 would then complain about a conversion from __int64 to int because the 
difference type of MyCountingIterator (using default) is __int64. Since we 
treat warnings as errors. I then changed MyCountingIterator to
    typedef boost::counting_iterator< boost::range_value< RangeType >::type, 
boost::use_default, boost::range_difference< RangeType >::type > 
MyCountingIterator;

This time I got a different error:
iterator_facade.hpp(554) : error C2784: '__w64 int 
boost::counting_iterator<Incrementable,CategoryOrTraversal,Difference>::distance_to(const 
boost::counting_iterator<OtherIncrementable> &) const' : could not deduce 
template argument for 'const boost::counting_iterator<OtherIncrementable> &' 
from 'const 
boost::counting_iterator<Incrementable,CategoryOrTraversal,Difference>'

My question is why limiting the last three template parameters to default in 
counting_iterator::distance_to.

Thanks,

Sean