(PHP 4 >= 4.0.6, PHP 5, PHP 7)
mb_strlen — Get string length
$str
   [, string $encoding = mb_internal_encoding()
  ] ) : intGets the length of a string.
strThe string being checked for length.
encodingThe encoding
parameter is the character encoding. If it is omitted, the internal character
encoding value will be used.
   Returns the number of characters in
   string str having character encoding
   encoding. A multi-byte character is
   counted as 1.
  
   If the encoding is unknown, an error of level
   E_WARNING is generated.