7 ms·

While I agree that 'z'++ being 'aa' is a bit silly, I can't ever see anyone making the case that 'aa' should be greater than 'z'.

by toolate 16y ago

msbarnett 16y ago
It's not that 'aa' would make any sense being greater than 'z', it's just the non-intuitive result that comes out of the combination of those features. To my mind it's a good example of how languages that try to throw in every feature and the kitchen sink end up acquiring a lot of bizarre warts from unforeseen interactions.
zackattack 16y ago
'z'++ is not 'aa'. 'z'++ is not even valid PHP. $z='z';$p=$z++; does nothing either. it's only in the for-loop context.
- Nitramp 16y ago
  Not really, after $p = $z++ $p is 'z', $z is 'aa', as you'd kind-of expect. But the difference between literals and expressions/variable references of course just adds icing to the cake of bizareness.
- rythie 16y ago
  try... <?php $z='z'; echo ++$z; which produces 'aa'
tel 16y ago
As long as we're enforcing ordering on casually unordered sets, when not define it as length of the string? Now 'aa' is certainly greater than 'z'.
- brianpan 16y ago
  There's a pretty good case for making the comparison closer to alphabetical ordering. 'apple' before 'pear' even though 'apple' is the longer string. 'z' before 'zz' also follows alphabetical ordering.
  - roel_v 16y ago
    That's what I was thinking, and in this case 'zz' would be > 'a'. I'd say that's a reasonable choice.
  - Nitramp 16y ago
    Note that there is no such thing as "the alphabetical ordering". Different languages define different collations, and some even multiple ones (e.g., German collation vs German phone book collation, or the various collation systems for Chinese characters). I'm pretty sure PHP's comparison operator will define non-ASCII characters as being outside of the alphabet, and probably just fail on multi-byte strings (UTF-8). So if you are doing comparisons on strings, you probably either have an i18n bug or a really, really specific use case.
trezor 16y ago
Clearly you have not ventured too far outside the "safe" en-US cultures ;) In the Scandinavian languages (Danish, Swedish and Norwegian) "aa" is (for whatever historical reasons) considered a synonym for "å", which is that last letter of the alphabet. In the same way "ae" maps "æ" (third last) and "oe" maps to "ø" (second last). Hence, using culture-aware sorting, the following array may actually not be sorted: [ "a", "aa", "ae", "b", "oe", "of" ]. You will find similar sort behaviour in a lot of databases when you set the database/table/column collation to other cultures. While I agree the PHP implementation is silly, your blanket dismissal of the possibility that 'aa' can't be greater than 'z' is equally ignorant.
- auxbuss 16y ago
  A couple of years ago I had to devise PHP sort algorithms for Danish, German, and Russian. (Unsurprisingly, native speakers are essential for testing this kind of thing ;) ) It was surprising at the time that these sort algorithms were not generally available in code. We also found that we couldn't rely on the db (MySql) to do the right thing, which was not helped, of course, by having these character sets, and others, in the db. The db was fully utf8. Once you grok PHP's underlying method, it's simply a case of using the above mentioned technique -- replacing the "foreign" symbols with character pairs -- to establish the correct order. In the Danish case above, for example, I used zx, zy, and zz.

While I agree that 'z'++ being 'aa' is a bit silly, I can't ever see anyone making the case that 'aa' should be greater than 'z'.

by toolate 16y ago

While I agree that 'z'++ being 'aa' is a bit silly, I can't ever see anyone making the case that 'aa' should be greater than 'z'.

msbarnett 16y ago

It's not that 'aa' would make any sense being greater than 'z', it's just the non-intuitive result that comes out of the combination of those features. To my mind it's a good example of how languages that try to throw in every feature and the kitchen sink end up acquiring a lot of bizarre warts from unforeseen interactions.

zackattack 16y ago

'z'++ is not 'aa'. 'z'++ is not even valid PHP. $z='z';$p=$z++; does nothing either. it's only in the for-loop context.

Nitramp 16y ago
Not really, after $p = $z++ $p is 'z', $z is 'aa', as you'd kind-of expect. But the difference between literals and expressions/variable references of course just adds icing to the cake of bizareness.
rythie 16y ago
try... <?php $z='z'; echo ++$z; which produces 'aa'

tel 16y ago

As long as we're enforcing ordering on casually unordered sets, when not define it as length of the string? Now 'aa' is certainly greater than 'z'.

brianpan 16y ago
There's a pretty good case for making the comparison closer to alphabetical ordering. 'apple' before 'pear' even though 'apple' is the longer string. 'z' before 'zz' also follows alphabetical ordering.
- roel_v 16y ago
  That's what I was thinking, and in this case 'zz' would be > 'a'. I'd say that's a reasonable choice.
- Nitramp 16y ago
  Note that there is no such thing as "the alphabetical ordering". Different languages define different collations, and some even multiple ones (e.g., German collation vs German phone book collation, or the various collation systems for Chinese characters). I'm pretty sure PHP's comparison operator will define non-ASCII characters as being outside of the alphabet, and probably just fail on multi-byte strings (UTF-8). So if you are doing comparisons on strings, you probably either have an i18n bug or a really, really specific use case.

trezor 16y ago

Clearly you have not ventured too far outside the "safe" en-US cultures ;) In the Scandinavian languages (Danish, Swedish and Norwegian) "aa" is (for whatever historical reasons) considered a synonym for "å", which is that last letter of the alphabet. In the same way "ae" maps "æ" (third last) and "oe" maps to "ø" (second last). Hence, using culture-aware sorting, the following array may actually not be sorted: [ "a", "aa", "ae", "b", "oe", "of" ]. You will find similar sort behaviour in a lot of databases when you set the database/table/column collation to other cultures. While I agree the PHP implementation is silly, your blanket dismissal of the possibility that 'aa' can't be greater than 'z' is equally ignorant.

auxbuss 16y ago
A couple of years ago I had to devise PHP sort algorithms for Danish, German, and Russian. (Unsurprisingly, native speakers are essential for testing this kind of thing ;) ) It was surprising at the time that these sort algorithms were not generally available in code. We also found that we couldn't rely on the db (MySql) to do the right thing, which was not helped, of course, by having these character sets, and others, in the db. The db was fully utf8. Once you grok PHP's underlying method, it's simply a case of using the above mentioned technique -- replacing the "foreign" symbols with character pairs -- to establish the correct order. In the Danish case above, for example, I used zx, zy, and zz.