On Fri, May 20, 2016 at 9:13 PM, Bruce Evans <b...@optusnet.com.au> wrote: > On Fri, 20 May 2016, Conrad Meyer wrote: > >> On Fri, May 20, 2016 at 6:10 PM, Bruce Evans <b...@optusnet.com.au> wrote: >>> >>> >>> Signed integers are easier to understand provided calculations with them >>> don't overflow. >> >> >> How? > > > For the same reasons as in applying mathematics. Applying mathematics > was harder before negative numbers were invented. Negative numbers > are actually not easy to understand at the technical level (the usual > representation of them is equivalence classes of pairs of non-negative > numbers), but their properties are easy to understand and work with > once you are familiar with them and don't think about their > implementation details too much. > > Ordinary (real) numbers (including negative ones) also have good ordering > properties for all operations. > > Computer arithmetic can't represent all ordinary numbers, but gets closest > by representing ordinary integers as C signed integers perfectly when no > overflow occurs. > > By using C unsigned integers unnecessarily, you throw out invention of > negative numbers and might have to work with the unfamiliar and badly > behaved ordering on them. C programmers have some experience with this > ordering, but apparently not enough to usually avoid bugs. > >> The rest of the argument seems to be, using u_int is bad because more >> unsigned is always bad. But I haven't seen a good reason to believe >> that is so. > > > Not always bad. Sometimes you must use C unsigned integers to get a full > representation without wasting many bits, or actually want the ordering > of unsigned integers. The main case is representing other C things like > pointers. Differences of pointers are still hard to handle. > > Bruce
Thanks for explaining. Can you explain a little bit about the badly behaved ordering of unsigned integers? I am not familiar with that. Best, Conrad _______________________________________________ svn-src-head@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-head To unsubscribe, send any mail to "svn-src-head-unsubscr...@freebsd.org"
