PHP获取当天、本周、本月、本季度、本年度时间

function get_date($date, $t = 'd', $n = 0)
{
    if ($t == 'd') {
        $firstday = date('Y-m-d 00:00:00', strtotime("$n day"));
        $lastday = date("Y-m-d 23:59:59", strtotime("$n day"));
    } elseif ($t == 'w') {
        if ($n != 0) {
            $date = date('Y-m-d', strtotime("$n week"));
        }
        $lastday = date("Y-m-d 23:59:59", strtotime("$date Sunday"));
        $firstday = date("Y-m-d 00:00:00", strtotime("$lastday -6 days"));
    } elseif ($t == 'm') {
        if ($n != 0) {
            $date = date('Y-m-d', strtotime("$n months"));
        }
        $firstday = date("Y-m-01 00:00:00", strtotime($date));
        $lastday = date("Y-m-d 23:59:59", strtotime("$firstday +1 month -1 day"));
    } elseif ($t == 'y') {
        $firstday = date("Y-01-01 00:00:00", strtotime($date));
        $lastday = date("Y-12-31 23:59:59", strtotime($date));
    } elseif (($t == 'q')) {
        $season = ceil(date('n',strtotime($date)) /3); //获取月份的季度
        $firstday = date('Y-m-01 00:00:00',mktime(0,0,0,($season - 1) *3 +1,1,date('Y')));
        $lastday =  date('Y-m-t 23:29:29',mktime(0,0,0,$season * 3,1,date('Y')));
    }
    return array($firstday, $lastday);
}