验证是否成年人

/** * 是否成年人 * @param string $birthday [出生年月] * @return boolean [description] */function isAdult($birthday){    if(empty($birthday))    {        return false;    }    list($year,$month,$day)=explode('-', $birthday);    if(empty($year)||empty($month)||empty($day))    {        return false;    }    $cyear=date('Y');    $cmonth=date('m');    $cday=date('d');    if(intval($cday)<intval($day))    {        $cmonth-=1;    }    if(intval($cmonth)<intval($month))    {        $cyear-=1;    }    if(intval($cyear)-intval($year) < 18)    {        return false;    }    return true;}