使用date_diff（）尝试这个非常简单的答案，这是经过测试的。

$date1 = date_create("2017-11-27");
$date2 = date_create("2018-12-29");
$diff=date_diff($date1,$date2);
$months = $diff->format("%m months");
$years = $diff->format("%y years");
$days = $diff->format("%d days");

echo $years .' '.$months.' '.$days;

输出为：

1 years 1 months 2 days

$date = '2012.11.13';
$dateOfReturn = '2017.10.31';

$substract = str_replace('.', '-', $date);

$substract2 = str_replace('.', '-', $dateOfReturn);



$date1 = $substract;
$date2 = $substract2;

$ts1 = strtotime($date1);
$ts2 = strtotime($date2);

$year1 = date('Y', $ts1);
$year2 = date('Y', $ts2);

$month1 = date('m', $ts1);
$month2 = date('m', $ts2);

echo $diff = (($year2 - $year1) * 12) + ($month2 - $month1);

<?php
    $today = strtotime("2011-02-03 00:00:00");
    $myBirthDate = strtotime("1964-10-30 00:00:00");
    printf("Days since my birthday: ", ($today - $myBirthDate)/60/60/24);
?>

DateInterval很好，但它有几个注意事项：

仅适用于PHP 5.3+（但这真的不再是一个好借口）仅支持年、月、日、小时、分钟和秒（无周）它计算上述所有+天的差异（你不能只计算月的差异）

为了克服这个问题，我编写了以下代码（由@enobrev答案改进而来）：

function date_dif($since, $until, $keys = 'year|month|week|day|hour|minute|second')
{
    $date = array_map('strtotime', array($since, $until));

    if ((count($date = array_filter($date, 'is_int')) == 2) && (sort($date) === true))
    {
        $result = array_fill_keys(explode('|', $keys), 0);

        foreach (preg_grep('~^(?:year|month)~i', $result) as $key => $value)
        {
            while ($date[1] >= strtotime(sprintf('+%u %s', $value + 1, $key), $date[0]))
            {
                ++$value;
            }

            $date[0] = strtotime(sprintf('+%u %s', $result[$key] = $value, $key), $date[0]);
        }

        foreach (preg_grep('~^(?:year|month)~i', $result, PREG_GREP_INVERT) as $key => $value)
        {
            if (($value = intval(abs($date[0] - $date[1]) / strtotime(sprintf('%u %s', 1, $key), 0))) > 0)
            {
                $date[0] = strtotime(sprintf('+%u %s', $result[$key] = $value, $key), $date[0]);
            }
        }

        return $result;
    }

    return false;
}

它运行两个循环；第一个算法通过暴力强制处理相对间隔（年和月），第二个算法通过简单的算法计算额外的绝对间隔（因此速度更快）：

echo humanize(date_dif('2007-03-24', '2009-07-31', 'second')); // 74300400 seconds
echo humanize(date_dif('2007-03-24', '2009-07-31', 'minute|second')); // 1238400 minutes, 0 seconds
echo humanize(date_dif('2007-03-24', '2009-07-31', 'hour|minute|second')); // 20640 hours, 0 minutes, 0 seconds
echo humanize(date_dif('2007-03-24', '2009-07-31', 'year|day')); // 2 years, 129 days
echo humanize(date_dif('2007-03-24', '2009-07-31', 'year|week')); // 2 years, 18 weeks
echo humanize(date_dif('2007-03-24', '2009-07-31', 'year|week|day')); // 2 years, 18 weeks, 3 days
echo humanize(date_dif('2007-03-24', '2009-07-31')); // 2 years, 4 months, 1 week, 0 days, 0 hours, 0 minutes, 0 seconds

function humanize($array)
{
    $result = array();

    foreach ($array as $key => $value)
    {
        $result[$key] = $value . ' ' . $key;

        if ($value != 1)
        {
            $result[$key] .= 's';
        }
    }

    return implode(', ', $result);
}

使用示例：

echo time_diff_string('2013-05-01 00:22:35', 'now');
echo time_diff_string('2013-05-01 00:22:35', 'now', true);

输出：

4 months ago
4 months, 2 weeks, 3 days, 1 hour, 49 minutes, 15 seconds ago

功能：

function time_diff_string($from, $to, $full = false) {
    $from = new DateTime($from);
    $to = new DateTime($to);
    $diff = $to->diff($from);

    $diff->w = floor($diff->d / 7);
    $diff->d -= $diff->w * 7;

    $string = array(
        'y' => 'year',
        'm' => 'month',
        'w' => 'week',
        'd' => 'day',
        'h' => 'hour',
        'i' => 'minute',
        's' => 'second',
    );
    foreach ($string as $k => &$v) {
        if ($diff->$k) {
            $v = $diff->$k . ' ' . $v . ($diff->$k > 1 ? 's' : '');
        } else {
            unset($string[$k]);
        }
    }

    if (!$full) $string = array_slice($string, 0, 1);
    return $string ? implode(', ', $string) . ' ago' : 'just now';
}

我不知道你是否在使用PHP框架，但很多PHP框架都有日期/时间库和助手来帮助你避免重新发明轮子。

例如，CodeIgniter具有timespan（）函数。只需输入两个Unix时间戳，就会自动生成如下结果：

1 Year, 10 Months, 2 Weeks, 5 Days, 10 Hours, 16 Minutes

http://codeigniter.com/user_guide/helpers/date_helper.html