(PHP 4 >= 4.0.6, PHP 5)
mb_substr — Get part of string
$str
   , int $start
   [, int $length = NULL
   [, string $encoding = mb_internal_encoding()
  ]] )
   Performs a multi-byte safe
   substr() operation based on
   number of characters. Position is
   counted from the beginning of
   str. First character's position is
   0. Second character position is 1, and so on. 
  
strThe string to extract the substring from.
start
       If start is non-negative, the returned string
       will start at the start'th position in
       string, counting from zero. For instance,
       in the string 'abcdef', the character at
       position 0 is 'a', the
       character at position 2 is
       'c', and so forth.
      
       If start is negative, the returned string
       will start at the start'th character
       from the end of string.
      
length
       Maximum number of characters to use from str. If
       omitted or NULL is passed, extract all characters to
       the end of the string.
      
encodingThe encoding
parameter is the character encoding. If it is omitted, the internal character
encoding value will be used.
   mb_substr() returns the portion of
   str specified by the
   start and
   length parameters.
  
| Version | Description | 
|---|---|
| 5.4.8 | Passing NULL as lengthextracts all characters to the end of the string. Prior to this version
        NULL was treated the same as 0. |