Bug->Doc #72567 [Opn->Ver]: PHP 7.1 changes in json_encode() wrt. encoding floats undocumented

Edit report at https://bugs.php.net/bug.php?id=72567&edit=1 ID: 72567 Updated by: cmb@php.net Reported by: sjon at hortensius dot net -Summary: json_encode results in rounding errors when encoding floats +Summary: PHP 7.1 changes in json_encode() wrt. encoding floats undocumented -Status: Open +Status: Verified -Type: Bug +Type: Documentation Problem Package: JSON related Operating System: 3v4l.org -PHP Version: Next Major Version +PHP Version: PHP 7.1 -Assigned To: +Assigned To: cmb Block user comment: N Private report: N New Comment: json_encode() now uses the ini option serialize_precision instead of precision when encoding double values. That behavioral change was a deliberate decision proposed and voted upon in RFC "More precise float value handling"[1]. Use ini_set('serialize_precision', 14) to restore the old behavior, see <https://3v4l.org/3ZuTQ>. [1] <https://wiki.php.net/rfc/precise_float_value> Previous Comments: ------------------------------------------------------------------------ [2016-07-09 10:34:34] sjon at hortensius dot net Description: ------------ Not sure what the correct terminology is for this; but it seems using json_encode with floats will result in 'rounding errors' as illustrated by the script below. This happens since alpha3 as can be seen on https://3v4l.org/q3SU6 Using JSON_NUMERIC_CHECK has no influence as can be seen on the original https://3v4l.org/TvGbe Test script: --------------- <?php echo json_encode(array(0.1, 0.2, 0.3, 0.4, 0.5, 0.6,)); Expected result: ---------------- [0.1,0.2,0.3,0.4,0.5,0.6] Actual result: -------------- [0.100000000000000005551115,0.20000000000000001110223,0.29999999999999998889777,0.40000000000000002220446,0.5,0.59999999999999997779554] ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=72567&edit=1