Answers for "how to use comma seprator in php"

explode comma php

$myString = "9,[email protected],8";
$myArray = explode(',', $myString);
print_r($myArray);

what is directory_separator in php

Because in different OS there is different directory separator. In Windows it's \ in Linux it's /. DIRECTORY_SEPARATOR is constant with that OS directory separator. Use it every time in paths.

In you code snippet we clearly see bad practice code. If framework/cms are widely used it doesn't mean that it's using best practice code.