strtotime

add a note User Contributed Notes

smartalco
26-Jul-2007 04:19


a simple way to find the first day of a month



<?php

echo date('l, F jS Y', strtotime("first day", strtotime("August 0 2007")));

?>



result:

Wednesday, August 1st 200

csnyder at chxo dot com
20-Jul-2007 07:23


Previous comments regarding dates prior to 1970 may be out of date. 

In PHP 5.2.3 on Linux:



<?php

$timestamp = strtotime( "February 26, 1946" );

print date( 'Y-m-d', $timestamp );

?>



Output is "1946-02-26", as expected.

ThomasK
19-Jul-2007 01:13


A major difference in behavior between PHP4x and newer 5.x versions is the handling of "illegal" dates: With PHP4, strtotime("2007/07/55") gave a valid result that could be used for further calculations.

This does not work anymore at PHP5.xx (here: 5.2.1), instead something like strtotime("$dayoffset_relative_to_today days","2007/07/19") is to be used.

olav dot morkrid at gmail dot com
07-Jul-2007 05:47


when using strtotime("wednesday"), you will get different results whether you ask before or after wednesday, since strtotime always looks ahead to the *next* weekday.



strtotime() does not seem to support forms like "this wednesday", "wednesday this week", etc.



the following function addresses this by always returns the same specific weekday (1st argument) within the *same* week as a particular date (2nd argument).



function weekday($day="", $now="") {



  $now = $now ? $now : "now";

  $day = $day ? $day : "now";



  $rel = date("N", strtotime($day)) - date("N");



  $time = strtotime("$rel days", strtotime($now));



  return date("Y-m-d", $time);



}



example use:



weekday("wednesday"); // returns wednesday of this week

weekday("monday, "-1 week"); // return monday the in previous week



ps! the ? : statements are included because strtotime("") without gives 1 january 1970 rather than the current time which in my opinion would be more intuitive...

Ian Fieggen
01-Jul-2007 02:54


To calculate the last Friday in the current month, use strtotime() relative to the first day of next month:



<?php

$lastfriday=strtotime("last Friday",mktime(0,0,0,date("n")+1,1));

?>



If the current month is December, this capitalises on the fact that the mktime() function correctly accepts a month value of 13 as meaning January of the next year.

matt
01-Jun-2007 03:10


Note about strtotime() when trying to figure out the NEXT month...



strtotime('+1 months'), strtotime('next month'), and strtotime('month') all work fine in MOST circumstances...



But if you're on May 31 and try any of the above, you will find that 'next month' from May 31 is calculated as July instead of June....

alanna at dramatis-personae dot com
13-May-2007 03:41


One more difference between php 4 and 5 (don't know when they changed this) but the string 15 EST 5/12/2007 parses fine with strtotime in php 4, but returns the 1969 date in php 5.  You need to add :00 to make it 15:00 so php can tell those are hours.  There's no change in php 4 when you do this.

Alan Gruskoff
08-Apr-2007 01:31


This function inputs a date sting and outputs an integer that is the internal representation of days that spreadsheets use. Post this value into a cell, then format that cell as a Date.



function conv_to_xls_date($Date) {

// Returns the Excel/Calc internal date integer from either an ISO date YYYY-MM-DD or MM/DD/YYYY formats.

    return (int) (25569 + (strtotime("$Date 12:00:00") / 86400));

}



example:



$Date = "04-07-2007";

$Days =  conv_to_xls_date($Date);



$Days will contain 39179

02-Mar-2007 11:29


SQL datetime columns have a much wider range of allowed values than a UNIX timestamp, and therefore this function is not safe to use to convert a SQL datetime column to something usable in PHP4.  Year 9999 is the limit for MySQL, which obviously exceeds the UNIX timestamp's capacity for storage.  Also, dates before 1970 will cause the function to fail (at least in PHP4, don't know about 5+), so for example my boss' birthday of 1969-08-11 returned FALSE from this function.





[red. The function actually supports it since PHP 5.1, but you will need to use the new object oriented methods to use them. F.e:


<?php


$date = new DateTime('1969-08-11');


echo $date->format('m d Y');


?>


]

sean at awesomeplay dot com
09-Feb-2007 08:29


Regarding the "NET" thing, it's probably parsing it as a time-zone.  If you give strtotime any timezone string (like PST, EDT, etc.) it will return the time in that time-zone.



In any case, you shouldn't use strtotime to validate dates.  It can and will give incorrect results.  As just one shining example:



Date: 05/01/2007



To most Americans, that's May 1st, 2007.  To most Europeans, that's January 5th, 2007.  A site that needs to serve people around the globe cannot use strtotime to validate or even interpret dates.



The only correct way to parse a date is to mandate a format and check for that specific format (preg_match will make your life easy) or to use separate form fields for each component (which is basically the same thing as mandating a format).

xurizaemon of the land of gmail
23-Jan-2007 09:17


Somewhere between PHP5.0 and PHP5.1.6, strtotime started accepting '.' (period, dot) as well as ':' (colon) as a time separator.





before: "2.30pm" == -1


after: "2.30pm" == 14:30





[red.: This is working since PHP 5.1.0]

LigH
16-Jan-2007 10:47


A hint not to misunderstand the second parameter:



The parameter "[, int now]" is only used for strings which describe a time difference to another timestamp.



It is not possible to use strtotime() to calculate a time difference by passing an absolute time string, and another timestamp to compare to!



Correct:



$day_before = strtotime("+1 day", $timestamp);

# result is a timestamp relative to another



Wrong:



$diff = strtotime("2007-01-15 11:40:00", time());

# result it the timestamp for the date in the string;

# because the string contains an absolute date and time,

# the second parameter is ignored!

# instead, use:

$diff = time() - strtotime("2007-01-15 11:40:00");

15-Oct-2006 09:50


Be careful, strtotime("+1 month", strtotime("2006-05-31"));

returns 2006-07-01!

sgutauckis
05-Oct-2006 07:02


The following might produce something different than you might expect:


<?php 


    echo date('l, F jS Y', strtotime("third wednesday", strtotime("2006-11-01"))) . "<br>";


    echo date('l, F jS Y', strtotime("third sunday", strtotime("2006-01-01")));


?>


Produces:


Wednesday, November 22nd 2006


Sunday, January 22nd 2006





The problem stems from strtotime when the requested day falls on the date passed to strtotime. If you look at your calendar you will see that they should return:





Wednesday, November 15th 2006


Sunday, January 15th 2006





Because the date falls on the day requested it skips that day.

d_spagnoli at yahoo dot it
11-May-2006 10:18


The GNU manual page has moved, the new address is 





http://www.gnu.org/software/shishi/manual/html_node/Date-input-formats.html

jacques dot malan at gmail dot com
11-Apr-2006 11:08


I have had some inconsistancies that was not immediately evident and suggested that strtotime treated my date formats in different ways.

I had trouble with the date format: d/m/Y



I eliminated the inconsistancies by changing the date format to one where (i guess) php does not try and guess the right format. In my case I changed it to the format (d-M-Y) in which case it worked.



Example when trying to find a person's age where:



//$date in format (d/m/Y) was inconsistant but fixed when in format (d-M-Y), e.g. (01-January-2001) 



$age = (time() - strtotime($date))/(60*60*24*360);

kturner at kgt dot net
24-Jan-2006 06:18


It looks like in the latest release of PHP 5.1, when passing to strtotime this string "12/32/2005", it will now return the date "12/31/1969". (The previous versions would return "1/1/2006".)

matt at australiangamer dot com
18-Jan-2006 12:32


Regarding the previous post on strtotime() being used to convert mysql datetime strings, I agree that this is not widely realized.



Part of the reason for this is that it is only a relatively recent addition. Prior to PHP 5.0, though it might have been an earlier version, strtotime() would return -1 on a mysql datetime string.



If you're on a server that doesn't have a recent PHP version test your result before assuming this one works.

shaver at qspeed dot com
11-Jan-2006 04:13


I'm posting these here as I believe these to be design changes, not bugs. 





For those upgrading from PHP 4 to PHP 5 there are a number of things that are different about strtotime that I have NOT seen documented elsewhere, or at least not as clearly. I confirmed these with two separate fresh installations of PHP 4.4.1 and PHP 5.1.1. 





1) Given that today is Tuesday: PHP4 "next tuesday" will return today. PHP5 "next tuesday" will actually return next tuesday as in "today +1week". Note that behavior has NOT changed for "last" and "this". For the string "last tuesday" both PHP4 and PHP5 would return "today -1week".  For the string "this tuesday" both PHP4 and PHP5 would return "today". 





2) You cannot include a space immediately following a + or - in PHP 5. In PHP4 the string "today + 1 week" works great. in PHP5 the string must be "today +1 week" to correctly parse. 





3) (Partially noted in changelog.) If you pass php4 a string that is a mess ("asdf1234") it will return -1. If you in turn pass this to date() you'll get a warning like: Windows does not support dates prior to midnight. This is pretty useful for catching errors in your scripts. In PHP 5 strtotime will return FALSE which causes date() to return 12/31/69. Note that this is true of strings that might appear right such as "two weeks". 





4) (Partially noted in changelog.) If you pass php4 an empty string it will error out with a "Notice: strtotime(): Called with empty time parameter". PHP5 will give no notice and return the current date stamp. (A much preferred behavior IMO.) 





5) Some uppercase and mixed-case strings no longer parse correctly. In php4 "Yesterday" would parse correctly. In php5 "Yesterday" will return the infamous 1969 date. This is also true of Tomorrow and Today. [Red. This has been fixed in PHP already]





6. The keyword "previous" is supported in PHP5. (Finally!) 





Good luck with your upgrades. :)


 -Will

Mr Obvious
10-Jan-2006 02:10


@ nick at fortawesome dot co dot uk

regarding 'month' vs 'next month'



Not sure what version of PHP you found those results on, however with PHP 4.4.0, 

<?PHP

$time1=strtotime('next month');

$time2=strtotime('month');

?>

produce the exact same result.

16-Dec-2005 01:31


Note that by default strtotime( ) considers the string time like a local time.

If your input string time is GMT/UTC do :



<?php

    $date = '2005-12-25 00:56:27 GMT' ; // Note the timezone specification

    $time = strtotime($date) ;

    echo date('d/m/Y H:i:s', $time) ; // $date will be correctly localized

    //  25/12/2005 01:56:27  for France

?>

Nathan
26-Oct-2005 02:03


The pluralization of "minute" or "minutes" for instance does not matter. In case you are dynamically using this function "+1 minutes" or "+2 minute" both do work.

nick at fortawesome dot co dot uk
26-Oct-2005 10:52


Note that strtotime('next month') will return 2 months from now, which may not be what you expect. strtotime('month') will do 1 month.

Rob Allen
06-Oct-2005 09:34


Note strtotime() in PHP 4 does not support fractional seconds.



See http://bugs.php.net/bug.php?id=28717 especially if you happen to swap to ODBC for MS SQL Server and wonder what's happened!

Philippe Jausions -at- 11abacus.com
28-Sep-2005 03:55


The PHP 5.1.0 change is a major backward compatibility break.





Now, that the returned value on failure has changed, the correct way to detect problems on all PHP versions is:





<?php





if (($time = strtotime($date)) == -1 || $time === false) {


    die 'Invalid date';


}





?>





[red (derick): note, this is not 100% correct, as in this case 1969-12-31 23:59 will be thrown out as that timestamp is "-1"]

sholland at napervillegi dot com
29-Aug-2005 01:25


One behavior to be aware of is that if you have "/" in the date then strtotime will believe the last number is the year, while if you use a "-" then the first number is the year.



12/4/03 will be evaluated to the same time as 03-12-4.



This is in the gnu documentation linked to in the article.  I confirmed the behavior with strtotime and getdate.



Steve Holland

tero dot totto at kymp dot net
15-Aug-2005 06:49


When using multiple negative relative items, the result might be a bit unexpected:



<?php

$basedate = strtotime("15 Aug 2005 10:15:00");

$date1 = strtotime("-1 day 2 hours", $basedate);

$date2 = strtotime("-1 day -2 hours", $basedate);

echo date("j M Y H:i:s", $date1);  // 14 Aug 2005 12:15:00

echo date("j M Y H:i:s", $date2);  // 14 Aug 2005 08:15:00

?>



The minus sign has to be added to every relative item, otherwise they are interpreted as positive (increase in time). Other possibility is to use "1 day 2 hours ago".

dcahhNOSPAM at gmx dot de
15-Jul-2005 09:21


Maybe it saves others from troubles:



if you create a date (i.e. a certain day, like 30.03.2005, for a calendar for example) for which you do not consider the time, when using mktime be sure to set the time of the day to noon:



<?php

    $iTimeStamp = mktime(12, 0, 0, $iMonth, $iDay, $iYear);

?>



Otherwhise 



<?php

    // For example

    strtotime('-1 month', $iTimeStamp);

?>



will cause troubles when calculating the relative time. It often is one day or even one month off... After I set the time to noon "strtotime" calculates as expected.



Cheers

Denis

timvw at users dot sourceforge dot net
12-Jul-2005 11:13


relative dates.. 



echo date('d F Y', strtotime('last monday', strtotime('15 July 2005'))); // 11th

echo "<br>";

echo date('d F Y', strtotime('this monday', strtotime('15 July 2005'))); // 18th

echo "<br>";

echo date('d F Y', strtotime('next monday', strtotime('15 July 2005'))); // 25th

ruben at wipkip dot com
28-Jun-2005 12:14


This is an easy way to calculate the number of months between 2 dates (including the months in which the dates are themselves).



<?



    $startDate = mktime(0,0,0, 6, 15, 2005);

    $stopDate = mktime(0,0,0, 10, 8, 2006);

    

    $nrmonths = ((idate('Y', $stopDate) * 12) + idate('m', $stopDate)) - ((idate('Y', $startDate) * 12) + idate('m', $startDate));



?>



Results in $nrmonths = 16.

LittleZephyr at nillahood dot net
09-May-2005 08:49


Here's a quick one-line function you can use to get the time difference for relative times. But default, if you put in a relative time (like "1 minute"), you get that relative to the current time. Using this function will give you just the time difference in seconds:



<?php function relative_time( $input ) { return strtotime($input) - time(); } ?>



For example "1 minute" will return 60, while "30 seconds ago" will return -30



Valid relative time formats can be found at http://www.gnu.org/software/tar/manual/html_chapter/tar_7.html#SEC115

miamiseb at nospam_gmail dot com
22-Apr-2005 04:59


If you strtotime the epoch (Jan 1 1970 00:00:00) you will usually get a value, rather than the expected 0. So for example, if you were to try to use the epoch to calculate the difference in times (strtotime(Jan 1 1970 21:00:00)-strtotime(Jan 1 1970 20:00:00) for example) You get a value that depends strongly upon your timezone. If you are in EST for example, the epoch is actually shifted -5 to YOUR epoch is Jan 1 1970 19:00:00) In order to get the offset, simply use the following call to report the number of seconds you are away from the unix epoch. $offset=strtotime("1970-01-01 00:00:00"); Additionally, you can append GMT at the end of your strtotime calls so save yourself the trouble of converting relative to timezone.

05-Apr-2005 06:45


I ran into the same problem with "last" as gabrielu at hotmail dot com (05-Apr-2005 10:45) when using strtotime() with getdate(). My only guess is that it has to do with daylight savings time as it seemed to be ok for most dates except those near the first Sunday in April and last Sunday in October.



I used strftime() with strtotime() and that gave me the result I was looking for.

gabrielu at hotmail dot com
05-Apr-2005 04:45


While working on an employee schedule application I noticed an issue with using strtotime('last...').  I ran tests on each weekday for each week within a year and noticed inconsistencies while using:



    date('m/d/Y', strtotime('last Wednesday', '2005-04-05'))



Most calculations of the 'last Wednesday' for each week calculated accordingly however I noticed a problem with several dates, one being '04/05/2005' (April 5th 2005).



    date('m/d/Y', strtotime('last Wednesday', '2005-04-05'))



The above should have returned '03/30/2005'.  Instead, it returned '03/29/2005'.  I don't understand why the function is returning this value.  Regardless, my solution:



    date('m/d/Y', strtotime('-1 week' ,strtotime('Wednesday', '2005-04-05')))

insta at citiesunlimited dot com
01-Apr-2005 10:56


Just a note ... there cannot be spaces between the + and the amount you want to add.



strtotime("{$myDate} -1 months") is correct.

strtotime("{$myDate} - 1 months") is not.



Caused me a headache ...

bishop
09-Dec-2004 04:12


Be warned that strtotime() tries to "guess what you meant" and will successfully parse dates that would otherwise be considered invalid:



<?php



$ts = strtotime('1999-11-40');

echo date('Y-m-d', $ts);



// outputs: 1999-12-10



?>



It is my understanding (I have not verified) that the lexer for strtotime() has been rewritten for PHP5, so these semantics may only apply for PHP4 and below.

maxz /* at */ rdtc /* dot */ ru
17-Sep-2004 10:52


When you convert date string got by untrusted source (such as If-Modified-Since HTTP Header) don't forget to check if the date string is empty.

<? strtotime('') ?>

returns current timestamp on my php 4.3.8

tim at komta dot com
20-Aug-2004 01:38


After a slight moment of frustration, and finding that I'm not the only one with this problem (see http://bugs.php.net/bug.php?id=28088 - it's a known bug) I decided to write a short workaround for dealing with the 00 hour problem.



The problem only seems to occur when inputting strings such as '08/20/2004 0047' and NOT '08/20/2004 00:47'.  Hence, my fix:



<?php

$your_value ( preg_replace ('#^(\d+/\d+/?\d{2,4} )(00)(\d{2})$#', '$1$2:$3', $your_value() ));

?>

cryogen at mac dot com
06-Apr-2004 06:39


I neglected to include the solution in my last post for using strtotime() with date-time data stored in GMT.  Append the string "GMT" to all of your datetimes pulled from MySQL or other database that store date-times in the format "yyyy-mm-dd hh:ii:ss" just prior to converting them to a unix timestamp with strtotime().  This will ensure you get a valid GMT result for times during daylight savings.



EXAMPLE:

<?php

$date_time1 = strtotime("2004-04-04 02:00:00"); // returns bad value -1 due to DST

$date_time2 = strtotime("2004-04-04 02:00:00 GMT"); // works great!

?>

kyle at frozenonline dot com
01-Jan-2004 11:24


I was having trouble parsing Apache log files that consisted of a time entry (denoted by %t for Apache configuration). An example Apache-date looks like: [21/Dec/2003:00:52:39 -0500]



Apache claims this to be a 'standard english format' time. strtotime() feels otherwise. 



I came up with this function to assist in parsing this peculiar format.



<?php

function from_apachedate($date)

{

        list($d, $M, $y, $h, $m, $s, $z) = sscanf($date, "[%2d/%3s/%4d:%2d:%2d:%2d %5s]");

        return strtotime("$d $M $y $h:$m:$s $z");

}

?>



Hope it helps anyone else seeking such a conversion.

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strtotime

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