关于PHP中获取随绝密码的疑问

function get_random_word($min_length, $max_length)  $word = '';  $dictionary = '/usr/dict/words';    $fp = @fopen($dictionary, 'r');  if(!$fp)    return false;   $size = filesize($dictionary);   srand ((double) microtime() * 1000000);  $rand_location = rand(0, $size);  fseek($fp, $rand_location);    while (strlen($word)< $min_length || strlen($word)>$max_length || strstr($word, "'"))  {       if (feof($fp))           fseek($fp, 0);        // if at end, go to start     $word = fgets($fp, 80);  // skip first word as it could be partial     $word = fgets($fp, 80);  // the potential password  };  $word=trim($word); // trim the trailing \n from fgets  return $word;  }