Hi I want to define a function is_rotation that check if a sequence is a rotation of another using the following algorithm: a.. First make sure s1 and s2 are of the same length. b.. Check to see if s2 is a substring of s1 concatenated with s1. I have started to implement this using boost range, using the join view to avoid the phisical concatenation but I'm not sure that testing 'boost::search(boost::join(s1,s1), s2) != end(boost::join(s1,s1))' is the best way to do with Boost.Range. bool is_rotation(std::string const &s1,std::string const &s2) { return (boost::size(s1) == boost::size(s2)) && boost::search(boost::join(s1,s1), s2) != end(boost::join(s1,s1))); } Sugestion for improvement? Best regards, _____________________ Vicente Juan Botet Escribá http://viboes.blogspot.com/