PHP DateTime函数返回本周未来的日期

I am trying to find the date range for "this week" using the following PHP code:

<?php

    date_default_timezone_set('Europe/London');

    $dateFrom = new DateTime('Monday this week');
    $dateTo = new DateTime('Sunday this week');

    $periodTextFrom = $dateFrom->format('Y/m/d 00:00:00');
    $periodTextTo = $dateTo->format('Y/m/d 23:59:59');

    echo $periodTextFrom.'<br>';
    echo $periodTextTo.'<br>';

?>

If I run today (Sunday 19th July 2015) it gives me the following output:

2015/07/20 00:00:00
2015/07/26 23:59:59

that is all in the future and not "this" week at all.

Why is this and how can I correct?

This should work for you :

 $today = getdate();

 $weekStart = $today['mday'] - $today['wday'];
 $weekEnd = $today['mday'] - $today['wday']+6;

 echo "week start:".$today['year']."/".$today['mon'].'/'.$weekStart."
week end:".$today['year']."/".$today['mon'].'/'.$weekEnd;