Calculate Age from Birth Year via PHP

Calculate User Age

<?php
$years = "1985"; //Assigned year of birth - This is the area you can pass your user's birth year

function calculateAge($birthdate)
{
      return floor((time() - strtotime($birthdate))/31556926);
}

print calculateAge($years)." year(s)"; //This one displays the user's actual age

?>

Calculate Days Remaining Till User Birthday and also User Age

<?php
function vpb_calculate_user_birthday($birthdate)
{
//If the user refuses to specify a birthday, just set today as birthday by default
if(empty($birthdate)) { $vpb_birthday_year_month_day = date("Y-m-d"); }
else { $vpb_birthday_year_month_day = $birthdate; }

// Current date which is today's date
$vpb_todays_date = date('Y-m-d');

//Get the Year, Month, Day from the given date of birth
$vpb_todays_date_array = explode('-',$vpb_todays_date);
$vpb_birthday_year_month_day_array = explode('-',$vpb_birthday_year_month_day);

//Pass Year, Month, Day to one variable as the user birthdate
$vpb_formatted_birthdate = $vpb_todays_date_array[0]."-".$vpb_birthday_year_month_day_array[1]."-".$vpb_birthday_year_month_day_array[2];

$vpb_date_difference = strtotime($vpb_formatted_birthdate)-time();//Current time returns in seconds
$vpb_age_calculation = time() - strtotime($vpb_birthday_year_month_day_array[0]);

// Days remaining till user birthday
$vpb_remaining_days = floor($vpb_date_difference/round(60*60*24));

//User age
$vpb_user_age = floor(($vpb_age_calculation)/round(60*60*24*365)); //31556926

if(strtotime($vpb_formatted_birthdate) < time())
{
$vpb_result = "Your birthday has passed for this year";
$vpb_result .= $vpb_user_age.' Years<br>';
}
else
{
if($vpb_remaining_days == 0)
{
$vpb_result = "Today is your birthday, Happy Birthday :) <br>";
$vpb_result .= $vpb_user_age.' Years<br>';
}
else
{
$vpb_result .= $vpb_remaining_days.' days remaining till your birthday<br>';
$vpb_result .= round($vpb_user_age-(1)).' Years<br>';
}
}
return $vpb_result;
}

//Birth Date Format: YYYY-MM-DD
echo vpb_calculate_user_birthday('1982-12-21');
?>