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Subject: Re: [PHP-DEV] [RFC] On the need of a `is_int_string` ?
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From: rob@bottled.codes ("Rob Landers")

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On Thu, Aug 15, 2024, at 17:42, Vincent Langlet wrote:
> Hi,
>=20
> 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."
>=20
> 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
>=20
> Currently most of static analysis rely on one/many native php function=
s to describe types.
> PHPStan/Psalm supports a `numeric-string` thanks to the `is_numeric` m=
ethod.
>=20
> I don't think there is a native function to know if the key will be ca=
sted to an int. The implementation would be something similar (but certa=
inly better and in C) to=20
> ```
> function is_int_string(string $s): bool
> {
> if (!is_numeric($s)) {
> return false;
> }=20
>=20
> $a[$s] =3D $s;
>=20
> return array_keys($a) !=3D=3D array_values($a);
> }
> ```
>=20
> Which gives:
> is_numeric('08') =3D> true
> ctype_digit('08') =3D> true
> is_int_string('08') =3D> false
>=20
> is_numeric('8') =3D> true
> ctype_digit('8') =3D> true
> is_int_string('8') =3D> true
>=20
> is_numeric('+8') =3D> true
> ctype_digit('+8') =3D> false
> is_int_string('+8') =3D> false
>=20
> is_numeric('8.4') =3D> true
> ctype_digit('8.4') =3D> false
> is_int_string('8.4') =3D> false
>=20
> Such method would allow to easily introduce a `int-string` type in sta=
tic analysis and the opposite, a `non-int-string` one (cf https://github=
.com/phpstan/phpstan/issues/10239#issuecomment-1837571316).
>=20
> WDYT about adding a `is_int_string` method then ?
>=20
> 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] ?? '') =3D=3D=3D '-' && ($s[1] ?? '=
') > 0)) && is_numeric($s);

I believe that covers all the cases that I could think of:

01, -01, +01, 1, 1.2, -1, -1.2, ~1, ~01

=E2=80=94 Rob
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<!DOCTYPE html><html><head><title></title><style type=3D"text/css">p.Mso=
Normal,p.MsoNoSpacing{margin:0}</style></head><body><div>On Thu, Aug 15,=
 2024, at 17:42, Vincent Langlet wrote:<br></div><blockquote type=3D"cit=
e" id=3D"qt" style=3D""><div dir=3D"ltr"><div>Hi,<br></div><div><br></di=
v><div>When string is used as an array key, it's sometimes casted to an =
int.<br></div><div>As explained in&nbsp;<a href=3D"https://www.php.net/m=
anual/en/language.types.array.php">https://www.php.net/manual/en/languag=
e.types.array.php</a>:<br></div><div>"Strings containing valid decimal i=
nts, unless the number is preceded by a&nbsp;+ 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."<br></div><div=
><br></div><div>This behavior cause some issues, especially for static a=
nalysis. As an example&nbsp;<a href=3D"https://phpstan.org/r/5a387113-de=
45-4bef-89af-b6c52adc5f69">https://phpstan.org/r/5a387113-de45-4bef-89af=
-b6c52adc5f69</a><br></div><div>vs real life&nbsp;<a href=3D"https://3v4=
l.org/pDkoB">https://3v4l.org/pDkoB</a><br></div><div><br></div><div>Cur=
rently most of static analysis rely on one/many native php functions to =
describe types.<br></div><div>PHPStan/Psalm supports a `numeric-string` =
thanks to the `is_numeric` method.<br></div><div><br></div><div>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 bette=
r and in C) to&nbsp;<br></div><div>```<br></div><div>function is_int_str=
ing(string $s): bool<br></div><div>{<br></div><div> if (!is_numeric($s))=
 {<br></div><div> return false;<br></div><div> } <br></div><div> <br></d=
iv><div> $a[$s] =3D $s;<br></div><div> <br></div><div> return array_keys=
($a) !=3D=3D array_values($a);<br></div><div>}<br></div><div>```<br></di=
v><div><br></div><div>Which gives:<br></div><div>is_numeric('08') =3D&gt=
; true<br></div><div>ctype_digit('08') =3D&gt; true<br></div><div>is_int=
_string('08') =3D&gt; false<br></div><div><br></div><div>is_numeric('8')=
 =3D&gt; true<br></div><div>ctype_digit('8') =3D&gt; true<br></div><div>=
is_int_string('8') =3D&gt; true<br></div><div><br></div><div>is_numeric(=
'+8') =3D&gt; true<br></div><div>ctype_digit('+8') =3D&gt; false<br></di=
v><div>is_int_string('+8') =3D&gt; false<br></div><div><br></div><div>is=
_numeric('8.4') =3D&gt; true<br></div><div>ctype_digit('8.4') =3D&gt; fa=
lse<br></div><div>is_int_string('8.4') =3D&gt; false<br></div><div><br><=
/div><div>Such method would allow to easily introduce a `int-string` typ=
e in static analysis and the opposite, a `non-int-string` one (cf&nbsp;<=
a href=3D"https://github.com/phpstan/phpstan/issues/10239#issuecomment-1=
837571316">https://github.com/phpstan/phpstan/issues/10239#issuecomment-=
1837571316</a>).<br></div><div><br></div><div>WDYT about adding a `is_in=
t_string` method then ?<br></div><div><br></div><div>Thanks<br></div></d=
iv></blockquote><div><br></div><div>Hello,<br></div><div><br></div><div>=
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 $=
key): bool`?</div><div><br></div><div>As for your function definition, i=
t can be simplified a bit:<br></div><div><br></div><div style=3D"backgro=
und-color:rgb(30, 31, 34);color:rgb(188, 190, 196);"></div><div style=3D=
"background-color:rgb(30, 31, 34);color:rgb(188, 190, 196);"><pre style=3D=
"font-family:&quot;Fira Code&quot;, monospace;font-size:9.8pt;"><span st=
yle=3D"color:rgb(207, 142, 109);">return </span><span style=3D"color:rgb=
(84, 168, 87);">(</span><span style=3D"color:rgb(53, 159, 244);">(</span=
><span style=3D"color:rgb(152, 118, 170);">$s</span><span style=3D"color=
:rgb(232, 186, 54);">[</span><span style=3D"color:rgb(42, 172, 184);">0<=
/span><span style=3D"color:rgb(232, 186, 54);">] </span>?? <span style=3D=
"color:rgb(106, 171, 115);">''</span><span style=3D"color:rgb(53, 159, 2=
44);">) </span>&gt; <span style=3D"color:rgb(42, 172, 184);">0 </span>||=
 <span style=3D"color:rgb(53, 159, 244);">(</span><span style=3D"color:r=
gb(110, 126, 217);">(</span><span style=3D"color:rgb(152, 118, 170);">$s=
</span><span style=3D"color:rgb(232, 186, 54);">[</span><span style=3D"c=
olor:rgb(42, 172, 184);">0</span><span style=3D"color:rgb(232, 186, 54);=
">] </span>?? <span style=3D"color:rgb(106, 171, 115);">''</span><span s=
tyle=3D"color:rgb(110, 126, 217);">) </span>=3D=3D=3D <span style=3D"col=
or:rgb(106, 171, 115);">'-' </span>&amp;&amp; <span style=3D"color:rgb(1=
10, 126, 217);">(</span><span style=3D"color:rgb(152, 118, 170);">$s</sp=
an><span style=3D"color:rgb(232, 186, 54);">[</span><span style=3D"color=
:rgb(42, 172, 184);">1</span><span style=3D"color:rgb(232, 186, 54);">] =
</span>?? <span style=3D"color:rgb(106, 171, 115);">''</span><span style=
=3D"color:rgb(110, 126, 217);">) </span>&gt; <span style=3D"color:rgb(42=
, 172, 184);">0</span><span style=3D"color:rgb(53, 159, 244);">)</span><=
span style=3D"color:rgb(84, 168, 87);">) </span>&amp;&amp; <span style=3D=
"color:rgb(87, 170, 247);">is_numeric</span><span style=3D"color:rgb(84,=
 168, 87);">(</span><span style=3D"color:rgb(152, 118, 170);">$s</span><=
span style=3D"color:rgb(84, 168, 87);">)</span>;<br></pre></div><div><br=
></div><div>I believe that covers all the cases that I could think of:<b=
r></div><div><br></div><div>01, -01, +01, 1, 1.2, -1, -1.2, ~1, ~01</div=
><div><br></div><div id=3D"sig121229152">=E2=80=94 Rob<br></div></body><=
/html>
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