How to Calculate age in Year, Month and Days PHP


<!DOCTYPE html>
<html>
<link rel="stylesheet" href="https://www.w3schools.com/w3css/4/w3.css">
<body>
   <div class="w3-orange w3-padding-64" style="width:50%;margin: 0 auto;padding: 10px 0;">
				  
				   <div class="w3-conatiner w3-center">
<?php
if(isset($_POST['save']))
{ 
$my = $_POST['birth_day']; date_default_timezone_set('Asia/Calcutta'); function findage($dob) { $localtime = getdate(); $today = $localtime['mday']."-".$localtime['mon']."-".$localtime['year']; $dob_a = explode("-", $dob); $today_a = explode("-", $today); $dob_d = $dob_a[0];$dob_m = $dob_a[1];$dob_y = $dob_a[2]; $today_d = $today_a[0];$today_m = $today_a[1];$today_y = $today_a[2]; $years = $today_y - $dob_y; $months = $today_m - $dob_m; $days=$today_d - $dob_d; if ($today_m.$today_d < $dob_m.$dob_d) { $years--; $months = 12 + $today_m - $dob_m; } if ($today_d < $dob_d) { $months--; } $firstMonths=array(1,3,5,7,8,10,12) $secondMonths=array(4,6,9,11); $thirdMonths=array(2); if($today_m - $dob_m == 1) { if(in_array($dob_m, $firstMonths)) { array_push($firstMonths, 0); } elseif(in_array($dob_m, $secondMonths)) { array_push($secondMonths, 0); }elseif(in_array($dob_m, $thirdMonths)) { array_push($thirdMonths, 0); } }
echo "<h3 class='w3-text-white' align='center'><strong> Age is $years years $months months $days Days.</strong></h3>"; } findage("$my"); //put date in the dd-mm-yyyy format } ?> <form method="post"> <P align="center"><input type="text" class="w3-input w3-border" name="birth_day" placeholder="Your Birth Date (dd-mm-yyyy)" style="width:50%"></p> <P align="center"> <input type="submit" class="w3-btn w3-brown w3-round" name="save" value="Know your age"></p> </form> </div> </body> </html>