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Bug #68551 filter_var return false for (float) $integer if strlen($integer) > ini_get('prec
Submitted: 2014-12-05 12:54 UTC Modified: 2021-03-31 14:29 UTC
Votes:3
Avg. Score:3.7 ± 1.2
Reproduced:3 of 3 (100.0%)
Same Version:2 (66.7%)
Same OS:3 (100.0%)
From: frederic dot hardy at mageekbox dot net Assigned: cmb (profile)
Status: Not a bug Package: Filter related
PHP Version: 5.6.3 OS: Linux/OSX
Private report: No CVE-ID: None
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 [2014-12-05 12:54 UTC] frederic dot hardy at mageekbox dot net 
Description:
------------
filter_var() with option FILTER_VALIDATE_INT return false if its argument is an integer casted to float with strlen($integer) > ini_get('precision').

Test script:
---------------
<?php

ini_set('precision', 14); // PHP default
$i = 12345678912345; // strlen($i) == 14
var_dump(strlen($i));
var_dump(filter_var((float) $i, FILTER_VALIDATE_INT)); // $i
var_dump((float) $i == $i); // true

$i = 123456789123456; // strlen($i) = 15
var_dump(strlen($i));
var_dump(filter_var((float) $i, FILTER_VALIDATE_INT)); // false instead of $i
var_dump((float) $i == $i); // true

Expected result:
----------------
int(14)
int(12345678912345)
bool(true)
int(15)
bool(123456789123456)
bool(true)

Actual result:
--------------
int(14)
int(12345678912345)
bool(true)
int(15)
bool(false)
bool(true)

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 [2014-12-05 14:43 UTC] ajf@php.net
-Status: Open +Status: Not a bug
 [2014-12-05 14:43 UTC] ajf@php.net 
Thank you for taking the time to write to us, but this is not
a bug. Please double-check the documentation available at
http://www.php.net/manual/ and the instructions on how to report
a bug at http://bugs.php.net/how-to-report.php

filter_var's FILTER_VALIDATE_INT always casts its argument to a string before conversion, and exponents and decimal points are never accepted, this is no exception.
 [2014-12-05 14:44 UTC] ajf@php.net 
(Though I agree it's pretty weird behaviour, FILTER_VALIDATE_INT could seriously be improved. Still, it's not actually a bug.)
 [2014-12-05 18:58 UTC] frederic dot hardy at mageekbox dot net 
So, filter_validate(1., FILTER_VALIDATE_INT) return (int) 1, but filter_validate(123456789123456., FILTER_VALIDATE_INT) return false, and it's not a bug. OK. All is right, we are in the PHP world!
 [2014-12-10 13:33 UTC] frederic dot hardy at mageekbox dot net 
Pierre just say me on IRC to add this script to illustrate the problem:

<?php

ini_set('precision', 2);
var_dump(filter_var(1.0, FILTER_VALIDATE_INT)); // int(1)
var_dump(filter_var(100.0, FILTER_VALIDATE_INT)); // bool(false)

?>

So, filter_var(1.0, FILTER_VALIDATE_INT) should return false, as filter_var(100.0, FILTER_VALIDATE_INT), or filter_var(100.0, FILTER_VALIDATE_INT) should return int(100)...
 [2014-12-10 14:05 UTC] frederic dot hardy at mageekbox dot net 
Moreover, to be clear:

<?php

ini_set('precision', 2);
$i = 100;
var_dump(filter_var((float) $i, FILTER_VALIDATE_INT)); // bool(false)
var_dump((float) $i == $i); // bool(true)

?>

So, how a float can be equal to an integer if it's not an integer ?
 [2014-12-11 02:42 UTC] pajoye@php.net
-Status: Not a bug +Status: Open
 [2014-12-11 02:42 UTC] pajoye@php.net 
Actually there are non sense inconsistencies here, due to the precision setting and conversion. Due to this, some dots may be accepted and other not if the length of the string representation of the value is bigger than the precision setting. This is a bug.
 [2021-03-31 14:29 UTC] cmb@php.net
-Status: Open +Status: Not a bug -Assigned To: +Assigned To: cmb
 [2021-03-31 14:29 UTC] cmb@php.net 
To clarify what Andrea already said:

<?php
ini_set('precision', 2);
echo (string) (float) 100;
?>

outputs as of PHP 8.0.0 (previously, the decimal separator was
locale dependent):

1.0E+2

Anyhow, 1.0E+2 is not a valid integer according to the
documentation of FILTER_VALIDATE_INT, and I have serious doubts
that we should change that behavior, even if we add a respective
flag, since in my opinion it makes no sense to pass a float to
filter_var() in the first place.

And anyway, this is not FILTER_VALIDATE_INT specific, but more a
general float to string conversion issue, see e.g. bug #66959.

I'm closing this as not a bug.  If anybody feels strongly that
this is a bug, or needs to be improved, please pursue the RFC
process[1].

[1] <https://wiki.php.net/rfc/howto>
 
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