PHP interception Chinese string function ~ including GB2312 and UT-8_PHP tutorial

/*
Chinese character interception function supported by Utf-8 and gb2312
cut_str(string, cut length, starting length, encoding);
The encoding defaults to utf-8
Start length defaults to 0
*/

function cut_str($string, $sublen, $start = 0, $code = 'UTF-8')
{
If($code == 'UTF-8')
{
$pa = "/[x01-x7f]|[xc2-xdf][x80-xbf]|xe0[xa0-xbf][x80-xbf]|[xe1-xef][x80-xbf][x80-xbf]| xf0[x90-xbf][x80-xbf][x80-xbf]|[xf1-xf7][x80-xbf][x80-xbf][x80-xbf]/";
          preg_match_all($pa, $string, $t_string);

If(count($t_string[0]) - $start > $sublen) return join('', array_slice($t_string[0], $start, $sublen))."...";
           return join('', array_slice($t_string[0], $start, $sublen));
}  
else
{
$start = $start*2;
         $sublen = $sublen*2;
          $strlen = strlen($string);
          $tmpstr = '';

for($i=0; $i< $strlen; $i++)
                                                                    If($i>=$start && $i< ($start+$sublen))
                                                                    If(ord(substr($string, $i, 1))>129)
                                                                                                              $tmpstr.= substr($string, $i, 2);
                                                                                                                                  else                                                                                                            $tmpstr.= substr($string, $i, 1);
                                                                                                                                                                                                                                                          If(ord(substr($string, $i, 1))>129) $i++;
         } 
If(strlen($tmpstr)< $strlen ) $tmpstr.= "...";
          return $tmpstr;
}  
}

$str = "The string that abcd needs to intercept";
echo cut_str($str, 8, 0, 'gb2312');
?>

//Intercept Chinese string
//Support GB2312
Function mysubstr($str, $start, $len) {
          $tmpstr = "";
          $strlen = $start + $len;
for($i = 0; $i < $strlen; $i++) {

                     $tmpstr .= substr($str, $i, 2);
$i++;
              } else
                        $tmpstr .= substr($str, $i, 1);
         } 
         return $tmpstr;
}  
?>

//Intercept utf8 string
function utf8Substr($str, $from, $len)
{
Return preg_replace('#^(?:[x00-x7F]|[xC0-xFF][x80-xBF]+){0,'.$from.'}'.
                    '((?:[x00-x7F]|[xC0-xFF][x80-xBF]+){0,'.$len.'}).*#s',
'$1',$str);
}
?>

Excerpted from Internet Marketing Blog