Bug #79843 [Opn->Nab]: Running intval to string value that is supposed to be INF returns 0

Edit report at https://bugs.php.net/bug.php?id=79843&edit=1 ID: 79843 Updated by: cmb@php.net Reported by: taira dot 815 dot terashima at gmail dot com Summary: Running intval to string value that is supposed to be INF returns 0 -Status: Open +Status: Not a bug Type: Bug Package: Strings related Operating System: Ubuntu18.04 PHP Version: 7.4.8 -Assigned To: +Assigned To: cmb Block user comment: N Private report: N New Comment: Thanks for the explanation, @nikic. Anyhow, the PHP manual says[1]: | If the float is beyond the boundaries of integer (usually +/- | 2.15e+9 = 2^31 on 32-bit platforms and +/- 9.22e+18 = 2^63 on | 64-bit platforms other than Windows), the result is undefined, | since the float doesn't have enough precision to give an exact | integer result. No warning, not even a notice will be issued when | this happens! [1] <https://www.php.net/manual/en/language.types.integer.php#language.types.integer.casting.from-float> Previous Comments: ------------------------------------------------------------------------ [2020-07-15 07:46:15] nikic@php.net @cmb: float -> int conversion does not perform a saturating cast, it performs a truncating cast. A good way to think of it is that we first cast the float to a bigint and then cast the bigint to a smaller integer size. As usual with integer casts, this will simply take the low bits and discard the high bits. The same happens with float -> int casts, just with more thorny details ;) ------------------------------------------------------------------------ [2020-07-15 01:14:53] taira dot 815 dot terashima at gmail dot com See this. <https://3v4l.org/1Pi3j> ------------------------------------------------------------------------ [2020-07-15 01:13:28] taira dot 815 dot terashima at gmail dot com Oh, I see. Sorry, One digit missing. If Add 0 to number's last, result were 0. ------------------------------------------------------------------------ [2020-07-13 09:59:08] cmb@php.net For numbers exceeding PHP_INT_MAX, intval() is supposed to return PHP_INT_MAX; see <https://3v4l.org/tf7EJ>. ------------------------------------------------------------------------ [2020-07-13 09:46:37] taira dot 815 dot terashima at gmail dot com Description: ------------ Running function intval using a string value more than a certain number (maybe DOUBLE MAX) returns 0. Test script: --------------- <?php // It returns 0. (This string value is 2^1024) $number = intval('179769313486231570772930519078902473361797697894230657273430081157732675805500963132708477322407536021120113879871393357658789768814416622492847430639474124377767893424865485276302219601246094119453082952085005768838150682342462881473913110540827237163350510684586298239947245938479716304835356329624224137216'); echo $number; Expected result: ---------------- INF Actual result: -------------- 0 ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=79843&edit=1