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::distance_to(const boost::counting_iterator<OtherIncrementable> &) const' : could not deduce template argument for 'const boost::counting_iterator<OtherIncrementable> &' from 'const boost::counting_iterator' My question is why limiting the last three template parameters to default in counting_iterator::distance_to. Thanks, Sean