PHP--年龄转生日、生日转年龄

 /**
      * 年龄转生日(模糊结果)
      * @parameter int age(年龄)
      * @parameter string symbol(分隔符)
      * @return string (yyyy*mm*dd)
      * @author he
      */
     private function agetobirthday($age,$symbol='-')
     {
         $age = $age==0?25:$age;
         $nowyear = date("Y",time());
         $year = $nowyear-$age;
         $monthArr = [];
         for ($i=1;$i<13;$i++){
             $monthArr[] = $i<10?'0'.$i:$i;
         }
         $dayArr = [];
         for ($i=1;$i<29;$i++){
             $dayArr[] = $i<10?'0'.$i:$i;
         }
         $month_key = array_rand($monthArr,1);
         $month = $monthArr[$month_key];
         $date_tmp_stamp = strtotime($year.'-'.$month);
         $day = '';
         if( $month=='02' && date("t",$date_tmp_stamp)=='29' ) {
             $dayArr = array_merge($dayArr,['29']);
             $day_key = array_rand($dayArr,1);
             $day = $dayArr[$day_key];
         } else if ( $month=='02' && date("t",$date_tmp_stamp)=='28' ){
             $day_key = array_rand($dayArr,1);
             $day = $dayArr[$day_key];
         } else if( in_array($month, ['01','03','05','07','08','10','12']) ) {
             $dayArr = array_merge($dayArr,['29','30','31']);
             $day_key = array_rand($dayArr,1);
             $day = $dayArr[$day_key];
         } else {
             $dayArr = array_merge($dayArr,['29','30']);
             $day_key = array_rand($dayArr,1);
             $day = $dayArr[$day_key];
         }
         return  $year.$symbol.$month.$symbol.$day;
     }

     /**
      * 生日转年龄
      * @author he
      * @parameter birthday:yyyy-mm-dd
      * @return str
      */
     private function birthdaytoage($birthday)
     {
         $age = 0;
         $year = date('Y',strtotime($birthday));
         $month = date('m',strtotime($birthday));
         $day = date('d',strtotime($birthday));

         $now_year = date('Y');
         $now_month = date('m');
         $now_day = date('d');

         if ($now_year > $year) {
             $age = $now_year - $year - 1;
             if ($now_month > $month) {
                 $age++;
             } else if ($now_month == $month) {
                 if ($now_day >= $day) {
                     $age++;
                 }
             }
         }
         if(empty($birthday)){
             $age = 26;
         }
         return $age;
     }