PHP: format human age

age_format.php

<?php

function formatAge($date, $point = null) {
    $date = DateTime::createFromFormat('Y-m-d', $date);
    $point = $point ? DateTime::createFromFormat('Y-m-d', $point) : new DateTime();
    $interval = $date->diff($point);

    if ($interval->format('%r%a') <= 0) {
        return false;
    }

    $years  = $interval->format('%y');
    $months = $interval->format('%m');
    $days   = $interval->format('%d');

    $parts = array();
    if ($years) {
        $parts[] = $years;
        $parts[] = ($years == 1 ? 'year' : 'years');

        if ($years < 3 && $months) {
            $parts[] = 'and';
            $parts[] = $months;
            $parts[] = ($months == 1 ? 'month' : 'months');
        }
    } elseif ($months) {
        $parts[] = $months;
        $parts[] = ($months == 1 ? 'month' : 'months');
    } else {
        $parts[] = $days;
        $parts[] = ($days == 1 ? 'day' : 'days');
    }

    return implode(' ', $parts);
}

$tests = array(
    '2014-10-20' => false,
    '2013-10-24' => '1 day',
    '2013-10-20' => '5 days',
    '2013-09-20' => '1 month',
    '2013-06-20' => '4 months',
    '2012-10-20' => '1 year',
    '2012-03-20' => '1 year and 7 months',
    '2011-10-20' => '2 years',
    '2011-03-20' => '2 years and 7 months',
    '2002-06-20' => '11 years'
);

foreach ($tests as $date => $correct) {
    echo (formatAge($date, '2013-10-25') === $correct ? 'yes' : 'no ') . ' :: ' . formatAge($date, '2013-10-25') . "\n";
}