UTF8转unicode

/**
 * UTF8转unicode
 * @param unknown_type $c
 */
function utf8_unicode($c) {
 switch (strlen ( $c )) {
  case 1 :
   return ord($c);
  case 2 :
   $n = (ord ( $c [0] ) & 0x3f) << 6;
   $n += ord ( $c [1] ) & 0x3f;
   break;
  case 3 :
   $n = (ord ( $c [0] ) & 0x1f) << 12;
   $n += (ord ( $c [1] ) & 0x3f) << 6;
   $n += ord ( $c [2] ) & 0x3f;
   break;
  case 4 :
   $n = (ord ( $c [0] ) & 0x0f) << 18;
   $n += (ord ( $c [1] ) & 0x3f) << 12;
   $n += (ord ( $c [2] ) & 0x3f) << 6;
   $n += ord ( $c [3] ) & 0x3f;
   break;
 }

 return $n;
}