"Nick Sabalausky" <a@a.a> wrote in message news:is3hoc$peu$1...@digitalmars.com... > "eles" <e...@eles.com> wrote in message > news:is2qgc$2o7h$1...@digitalmars.com... >>> The right boundary of a slice is exclusive. >> >> I think it should be stated more obvious in the paper. >> >>> This makes sense, so you can >>> do stuff like a[1..$] (== a[1..a.length]) to get a slice that >> contains >>> all elements of a except for the first one (a[0]). >> >> I disagree, but I have not much influence here, although I will >> defend my point of view. I find it quite unpleasant to remember which >> of the left and right bounds are exclusive and, moreover, this >> precludes slicing with a[i1..i2] where i1 and i2 are only known at >> the runtime and may be i2<i1 (and not necessarily i1<i2). >> > > When I first started with D, ages ago, I was skeptical about the half-open > slices. It sounded unbalanced. But since then, I've been won over by it > for a few reasons (in no particular order): > > 1. After years of using D, I've never had a problem with it working that > way. And even initially, I found it very easy to learn and get used to it. > > 2. I've found it easier to avoid off-by-one errors. I don't have to think > about them as much. > > 3. arr[a..b].length == b-a <-- That's a *very* nice, clean, useful > property to have. And I think it's one of the main reasons for #2 above. > In fact, this actually makes it feel more balanced to me than having > inclusive on both ends. > > 4. The following: > > string str = "ABCDEF"; > int splitIndex = 3; > > string part1 = str[0 .. splitIndex]; > string part2 = str[splitIndex .. $]; > > assert(part1 ~ part2 == str); > > Ie, when you split an array, you can use the same index for both halves. > No "+1"-ing. It just works. Don't have to think about it. >
Another way I often like to think of it is, if you'll pardon the ASCII-art, a slice looks like this: ___________ <___________< Like stackable cups. They "fit" together. Nice, neat and tidy. But if it were inclusive on both ends, it would look like this: ___________ <___________> Those don't fit together. Messy.
