Re: Negative string offsets

On 04/17/2014 08:07 AM, Johannes Schlüter wrote: > On Thu, 2014-04-17 at 17:18 +0300, Andrey Andreev wrote: >> For example, every time you need to check for a filename extension, >> last segment of a path, etc. When I need that, I always endup with >> substr(), strrchr() or explode(), end() ... both are suboptimal. > > I don't see where this helps in that case. > > $sep = strrpos($filename, "."); > if ($sep !== false) { > $ext = substr($filename, $sep + 1); > } > > is clear and concise, two fcalls, can be understood even after years and > the new programmer easily. > > This is the most concise form I came up using this new offset: > > $ext = ''; > $pos = -1; > do { > $ext = $filename[$pos].$ext; > } while ($filename[--$pos] != '.'); > > While this form is bugged as it assumes that there is a . without > checking. For checking I'd have to use strlen(), but if i call strlen() > I can also initialize $pos accordingly and iterate from strlen() to 0. > Also this form does more comparisons and way more allocations and is (in > my opinion) way harder to understand. > > Maye I didn't see a simple form ... Yeah, it wouldn't make any sense unless it supported ranges. Something like: if($filename[-4,4] === '.ext') ... although, I don't see how that is better than: if(substr($filename,-4) === '.ext') ... The latter is much clearer. -Rasmus