Ali Ãehreli Wrote: > On 11/11/2011 01:42 PM, Steven Schveighoffer wrote: > > On Fri, 11 Nov 2011 16:10:12 -0500, Simon <s.d.hamm...@gmail.com> wrote: > > > >> On 11/11/2011 19:04, Steven Schveighoffer wrote: > >>> On Fri, 11 Nov 2011 14:01:42 -0500, Steven Schveighoffer > >>> <schvei...@yahoo.com> wrote: > >>> > >>>> There should be no bounds error in any case, an empty slice is valid. > >>> > >>> By "in any case" I meant in either debug or release mode. > >>> > >>> -Steve > >> > >> even when you index beyond the bounds of the slice? > >> > >> you may not actually be reading memory because it's zero length, but > >> it's still logically invalid; you've gone outside the valid range. > > > > You are not reading beyond the valid range. A zero-length slice is > > perfectly legal to point at the end of an array or other slice. Reading > > any data from a zero-length slice will cause an out-of-bounds error in > > debug mode, because it has no elements. > > > >> in vc9, if you increment an iterator beyond the valid range you get a > >> debug assert. that's caught quite a few bugs where I work when we > >> upgraded to vc9. > > > > I think you are misunderstanding what the $ actually means. > > > > It's the equivalent in C++ iterators to x.end. > > > > The pair of iterators x.end, x.end is a valid range. Going *beyond* > > x.end would be illegal. But iterating *to* x.end is legal (which would > > be the equivalent of [$..$] range), and you will not be able to convince > > me that vc9 doesn't allow it. > > > > -Steve > > How about Jonathan's this comment: "It wouldn't surprise me if arr[500 > .. 500] worked exactly the same way. Because the array is empty, it > doesn't really matter what values you gave it." > > I think Simon is objecting to 500..500 being accepted (if at all). I > agree that $..$ is correct. > > Ali
Oh my mistake! I thought we were talking about arr[$..$]! Yes, arr[500..500] would result in bounds errors if the array is only 7 elements. When I read it I thought it was just an arbitrary example to show another way to get an empty slice with an assumption that 500 is a valid index. -Steve
