Validate Age to be greater or equal to 18

valdiate_age.php

<?php
/**
 * Validate Age to be greater or equal to 18
 *
 * @param  $birthdate
 * @return boolean
 */
function validateAge($birthdate)
{
	$currentDate = new DateTime("now");
	$birthdate = new DateTime($birthdate);

	$interval = date_diff($currentDate, $birthdate);
	// var_dump($interval->y);

	if ($interval->y >= 18)
	    return true;
	else
	    return false;
}