mb_check_encoding

(PHP 4 >= 4.4.3, PHP 5 >= 5.1.3, PHP 7)

mb_check_encoding — Check if the string is valid for the specified encoding

mb_check_encoding ([ string $var = NULL [, string $encoding = mb_internal_encoding() ]] ) : bool

Checks if the specified byte stream is valid for the specified encoding. It is useful to prevent so-called "Invalid Encoding Attack".

var: The byte stream to check. If it is omitted, this function checks all the input from the beginning of the request.
encoding: The expected encoding.

Returns TRUE on success or FALSE on failure.