PHP calculates age/zodiac/constellation based on birthday example

function birthday($mydate){ 
    $birth=$mydate; 
    list($by,$bm,$bd)=explode('-',$birth); 
    $cm=date('n'); 
    $cd=date('j'); 
    $age=date('Y')-$by-1; 
    if ($cm>$bm || $cm==$bm && $cd>$bd) $age++; 
    return $age; 
//echo "生日:$birthn年龄:$agen"; 
}

<?php 
/** 
 *  计算.生肖 
 *  
 * @param int $year 年份 
 * @return str 
 */ 
function get_animal($year){ 
    $animals = array( 
            &#39;鼠&#39;, &#39;牛&#39;, &#39;虎&#39;, &#39;兔&#39;, &#39;龙&#39;, &#39;蛇&#39;,  
            &#39;马&#39;, &#39;羊&#39;, &#39;猴&#39;, &#39;鸡&#39;, &#39;狗&#39;, &#39;猪&#39; 
    ); 
    $key = ($year - 1900) % 12; 
    return $animals[$key]; 
}
echo get_animal(1990);    // 马 
echo get_animal(2010);    // 虎

<?php 
/** 
 *  计算.星座 
 * 
 * @param int $month 月份 
 * @param int $day 日期 
 * @return str 
 */ 
function get_constellation($month, $day){ 
    $signs = array( 
            array(&#39;20&#39;=>&#39;宝瓶座&#39;), array(&#39;19&#39;=>&#39;双鱼座&#39;), 
            array(&#39;21&#39;=>&#39;白羊座&#39;), array(&#39;20&#39;=>&#39;金牛座&#39;), 
            array(&#39;21&#39;=>&#39;双子座&#39;), array(&#39;22&#39;=>&#39;巨蟹座&#39;), 
            array(&#39;23&#39;=>&#39;狮子座&#39;), array(&#39;23&#39;=>&#39;处女座&#39;), 
            array(&#39;23&#39;=>&#39;天秤座&#39;), array(&#39;24&#39;=>&#39;天蝎座&#39;), 
            array(&#39;22&#39;=>&#39;射手座&#39;), array(&#39;22&#39;=>&#39;摩羯座&#39;) 
    ); 
    $key = (int)$month - 1; 
    list($startSign, $signName) = each($signs[$key]); 
    if( $day < $startSign ){ 
        $key = $month - 2 < 0 ? $month = 11 : $month -= 2; 
        list($startSign, $signName) = each($signs[$key]); 
    } 
    return $signName; 
}
echo get_constellation(12, 11);    // 射手座 
echo get_constellation(6, 6);      // 双子座