Robert Jones wrote:

copy( counting_range( 1, 5 ) | reversed | transformed( f ), std::ostream_iterator<int>( std::cout, " " ) ); std::cout << std::endl;

copy( counting_range( 1, 5 ) | reversed | transformed( bind( f, _1 ) ), std::ostream_iterator<int>( std::cout, " " ) ); std::cout << std::endl;

[...]

Which is...

8 6 4 2 1768406272 1768406272 1768406272 1768406272

This is because dereferencing `reverse_iterator` of `counting_iterator` makes a reference to a dead temporary. See #2640 https://svn.boost.org/trac/boost/ticket/2640 Use `irange( 1, 5 )` instead. Regards, Michel

On 15 March 2013 at 14:51, Robert Jones wrote:

Hi Folks

Can anyone explain the output of this program...

#include <iostream> #include #include #include #include #include #include

int f( int i ) { return i * 2; }

int main( ) { using boost::adaptors::reversed; using boost::adaptors::transformed; using boost::counting_range; using boost::copy; using boost::phoenix::arg_names::_1;

copy( counting_range( 1, 5 ) | reversed | transformed( f ), std::ostream_iterator<int>( std::cout, " " ) ); std::cout << std::endl;

copy( counting_range( 1, 5 ) | reversed | transformed( bind( f, _1 ) ), std::ostream_iterator<int>( std::cout, " " ) ); std::cout << std::endl; }

Which is...

8 6 4 2 1768406272 1768406272 1768406272 1768406272

I'm using Gcc 4.6.2 & Boost 1.53

Thx All.

Michel Morin was long ago kind enough to diagnose this problem as being due to https://svn.boost.org/trac/boost/ticket/2640 which is about whether iterators may and should own their referents, but my trac-foo is not quite up to being certain whether this was ever fixed or indeed could or should be fixed. I'd appreciate a quick sentence confirming the current situation. Thx, Rob.