On Thu, Aug 15, 2024, at 17:42, Vincent Langlet wrote: > Hi, > > When string is used as an array key, it's sometimes casted to an int. > As explained in https://www.php.net/manual/en/language.types.array.php: > "Strings containing valid decimal ints, unless the number is preceded by a + > sign, will be cast to the int type. E.g the key "8" will actually be stored > under 8. On the other 08 will not be cast as it isn't a valid decimal > integer." > > This behavior cause some issues, especially for static analysis. As an > example https://phpstan.org/r/5a387113-de45-4bef-89af-b6c52adc5f69 > vs real life https://3v4l.org/pDkoB > > Currently most of static analysis rely on one/many native php functions to > describe types. > PHPStan/Psalm supports a `numeric-string` thanks to the `is_numeric` method. > > I don't think there is a native function to know if the key will be casted to > an int. The implementation would be something similar (but certainly better > and in C) to > ``` > function is_int_string(string $s): bool > { > if (!is_numeric($s)) { > return false; > } > > $a[$s] = $s; > > return array_keys($a) !== array_values($a); > } > ``` > > Which gives: > is_numeric('08') => true > ctype_digit('08') => true > is_int_string('08') => false > > is_numeric('8') => true > ctype_digit('8') => true > is_int_string('8') => true > > is_numeric('+8') => true > ctype_digit('+8') => false > is_int_string('+8') => false > > is_numeric('8.4') => true > ctype_digit('8.4') => false > is_int_string('8.4') => false > > Such method would allow to easily introduce a `int-string` type in static > analysis and the opposite, a `non-int-string` one (cf > https://github.com/phpstan/phpstan/issues/10239#issuecomment-1837571316). > > WDYT about adding a `is_int_string` method then ? > > Thanks
Hello, At the risk of bikeshedding, it would probably be better to define it in the `array_*` space, maybe something like `array_key_is_string(string $key): bool`? As for your function definition, it can be simplified a bit: return (($s[0] ?? '') > 0 || (($s[0] ?? '') === '-' && ($s[1] ?? '') > 0)) && is_numeric($s); I believe that covers all the cases that I could think of: 01, -01, +01, 1, 1.2, -1, -1.2, ~1, ~01 — Rob
