(PHP 5 >= 5.2.0, PHP 7)
Finds first occurrence of a string within another, case insensitive
string mb_stristr ( string $haystack, string $needle [, bool $before_needle = false [, string $encoding = mb_internal_encoding() ]] )
mb_stristr() finds the first occurrence of needle in haystack and returns the portion of haystack. Unlike mb_strstr(), mb_stristr() is case-insensitive. If needle is not found, it returns FALSE.