Description:
------------
<?php
/*
A programmer who does not understand English
The description is with Machine Translation
*/
// Only 32 ~ 122 / whole number will appear, small digital specific.13 and 0.02
                $c = 122.13 + 0.02;
                print_r($c);  //  105.15
                echo "<br />";
                echo json_encode($c);  //  105.14999999999999
                echo "<br />";
                echo json_encode(105.15);  //  105.15

Test script:
---------------
<?php
/*
A programmer who does not understand English
The description is with Machine Translation

PHP Version 7.2.0
json Version  1.6.0
*/
// Only 32 ~ 122 / whole number will appear, small digital specific.13 and 0.02
                $c = 122.13 + 0.02;
                print_r($c);  //  105.15
                echo "<br />";
                echo json_encode($c);  //  105.14999999999999
                echo "<br />";
                echo json_encode(105.15);  //  105.15

Expected result:
----------------
                echo json_encode($c);  //  105.15

Actual result:
--------------
echo json_encode($c);  //  105.14999999999999