showAge函数的作用是什么..

while ($value = $_SGLOBAL['db']->fetch_array($query)) {
  //realname_set($value['uid'], $value['username']);
  $value['age'] = showAge($value['birthyear']);
  $value['username2'] = addslashes(getstr($value['username'], 12, 0, 0, 0, 0, -1));
  $value['aboutme'] = addslashes(getstr($value['aboutme'], 60, 0, 0, 0, 0, -1));
  $value['avatar'] = avatar($value[uid],big,true);
  $netcache['showlist'][] = $value;
}

谁能告诉我此函数的作用