life-expectancy.php

<?php
/**
 * Calculate your life expectancy and
 * send a notification email every day
 */

//set the default timezone to UTC
date_default_timezone_set('UTC');

/**
 * Return the date object with life expectancy
 * @param  integer $birthDate  birth date string eg 1990-2-20
 * @param  integer $expectancy  life expectancy eg 79
 * @return DateInterval          DateInterval object
 */
function spit_life_expectancy($birthDate, $expectancy) {
	$now = new DateTime("now"); //time now
	$exp = new DateTime($birthDate); //begening of your life

	$exp->add(new DateInterval("P{$expectancy}Y"));

	return $now->diff($exp); //return the object
}

$expectancy = spit_life_expectancy('1990-05-21', 80);

$exptancy = "Life Expectancy: {$expectancy->y} years, {$expectancy->m} months, {$expectancy->d} days";
echo $exptancy;