Description:
------------
<?php
$a=1.2;
$b=1;
$c=$a-$b;
echo json_encode($c);
?>
php.ini : serialize_precision =-1
sometimes it echo 0.2 ; sometimes it echo 0.1999999999999996

Test script:
---------------
<?php
$a=1.2;
$b=1;
$c=$a-$b;
echo json_encode($c);
?>
php.ini : serialize_precision =-1
sometimes it echo 0.2 ; sometimes it echo 0.1999999999999996

Expected result:
----------------
sometimes it echo 0.2 ; sometimes it echo 0.1999999999999996

Actual result:
--------------
json_encode float error