php incrementing time stamp error?

问题

I have a pagination function which pages through a time table and advances the dates on a weekly basis and displays the details relevant to the new dates.

Whilst testing some new data I encountered a paging problem. In that it would not page passed 22/10/2012.

Debugging the code I eventually found the source of the problem which is that incrementing the date stamp representing 22/10/2012 by 7 days returned (via strftime) a date of 28/10/2012 when obviously I was expecting a date of the 29/10/2012. This error effectively causing a continuous loop as %W (which drives the weekly pagination) is 43 for 22/10/2012 and 43 for 28/10/2012 and of course it should be 44 for 29/10/2012.

In a quick test to isolate and recreate this problem I used the following:

/*
 * test %W
 */

$time_Stamp_1 = mktime(0,0,0,10,22,2012);
echo "date : " . strftime("%d/%m/%Y", $time_Stamp_1);
echo "W for first time stamp " . $time_Stamp_1 . " is " . strftime("%W", $time_Stamp_1); 

$time_Stamp_1a = $time_Stamp_1 += (60 * 60 * 24 * 7);
echo "new date : " . strftime("%d/%m/%Y", $time_Stamp_1a);
echo "W for new date time stamp: " . strftime("%W", $time_Stamp_1a);

$time_Stamp_2 = mktime(0,0,0,10,29,2012);
echo "W for second time stamp: " . strftime("%W", $time_Stamp_2);

The pagination happily moves between all the other weeks I have tested and obviously uses this increment / decrement as appropriate.

Hopefully I am missing something obvious. Any thoughts?

回答1:

The PHP DateTime class is the way to go:-

$inFormat = 'd/m/Y h:i';
$outFormat = 'd/m/Y';
$date = DateTime::createFromFormat($inFormat, '22/10/2012 00:00');
$interval = new DateInterval('P7D');
for($i = 0; $i < 10; $i++){
    $date->add($interval);
    var_dump($date->format($outFormat) . " is in week " . $date->format('W'));week');
}

Gives the following output:-

string '29/10/2012 is in week 44' (length=24)
string '05/11/2012 is in week 45' (length=24)
string '12/11/2012 is in week 46' (length=24)
string '19/11/2012 is in week 47' (length=24)
string '26/11/2012 is in week 48' (length=24)
string '03/12/2012 is in week 49' (length=24)
string '10/12/2012 is in week 50' (length=24)
string '17/12/2012 is in week 51' (length=24)
string '24/12/2012 is in week 52' (length=24)
string '31/12/2012 is in week 01' (length=24)

Which, a quick glance at a calendar tells me, is correct.

See here for valid format strings http://us.php.net/manual/en/datetime.createfromformat.php
Also see the DateInterval class.

See here for valid output formats for DateTime::format() http://us.php.net/manual/en/function.date.php

回答2:

Or better yet use DateTime.

 // Create the DateTime object
 $date = new DateTime('2012-22-10');
 echo $date->format('d/m/Y');

 // Add one week
 $date->modify('+1 week');
 echo $date->format('d/m/Y');

回答3:

Try using strtotime() for time calculations - e.g. to get the next week use:

$time_Stamp_1a = strtotime("+1 week", $time_Stamp_1);

来源：https://stackoverflow.com/questions/12511325/php-incrementing-time-stamp-error

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