[Boost-users] [regex] match_results: signatures of position(sub) and length(sub) are different, why?

Hi, On the following link, we can see that length and position member functions have different signatures: http://www.boost.org/doc/libs/1_52_0/libs/regex/doc/html/boost_regex/ref/mat... difference_type length(int sub = 0) const; difference_type position(unsigned int sub = 0) const; Why int for length(sub) and unsigned int for position(sub)? Frédéric