Last updated: Fri, 05 Sep 2008

mktime

(PHP 4, PHP 5)

mktime — 日付を Unix のタイムスタンプとして取得する

説明

int mktime ([ int $hour [, int $minute [, int $second [, int $month [, int $day [, int $year [, int $is_dst ]]]]]]] )

与えられた引数に従って UNIX のタイムスタンプを返します。このタイムスタンプは、Unix epoch(1970年1月1日00:00:00 GMT)から指定された時刻までの通算秒を表す長整数です。

引数は右から順に省略することができます。省略された引数は、ローカルの日付と時刻に従って、現在の値にセットされます。

パラメータ

hour: 時
minute: 分
second: 秒
month: 月
day: 日
year: 年。2 桁または 4 桁の値を指定可能で、 0-69 の間の値は 2000-2069 に、70-100 は 1970-2000 にマップされます。今日最も一般的なシステム、すなわち time_t が 32 ビットの符号付き整数であるシステムでは year として有効な範囲は 1901 から 2038 の間です。しかし、PHP 5.1.0 より前のバージョンではこの範囲が 1970 から 2038 に制限されているシステム (たとえば Windows) もありました。
is_dst: このパラメータはサマータイム (DST) の時に1にセットされ、そうでない時に0、サマータイムであるかどうかが不明である場合に-1 にセットされます。不明な場合、PHP はサマータイムかどうか推測しようとします。 PHP を実行しているシステムで DST が有効になっている、もしくは is_dst が 1 にセットされている場合、一部の時刻は有効になりません。もし DST が有効で例えば 2:00 の場合、2:00 から 3:00 までの全ての時刻は無効になり、mktime() は不確定な値 (通常は負数) を返します。いくつかのシステム (例えば Solaris 8) は真夜中に DST を有効にしますので、DST が有効なときの 0:30 は前日の 23:30 と評価されます。

注意: PHP 5.1.0 以降、このパラメータは廃止されました。その結果、新しいタイムゾーン処理機能がかわりに使用されます。

返り値

mktime() は与えられた引数の Unix タイムスタンプを返します。引数が不正な場合、この関数は FALSE を返します（PHP 5.1 より前のバージョンでは -1 を返していました）。

エラー / 例外

すべての日付/時刻関数は、有効なタイムゾーンが設定されていない場合に E_NOTICE を発生させます。また、システム設定のタイムゾーンあるいは環境変数 TZ を使用した場合には E_STRICT を発生させます。 date_default_timezone_set() も参照ください。

変更履歴

バージョン	説明
5.3.0	mktime() は、 `is_dst` パラメータを使用した場合に E_DEPRECATED をスローするようになりました。
3.0.10	`is_dst` パラメータが追加されました
5.1.0	`is_dst` パラメータは廃止されました。エラー時には -1 ではなく `FALSE` を返すようになりました。年月日がすべてゼロとすることが可能になりました。
5.1.0	タイムゾーンがおかしい場合に `E_STRICT` や `E_NOTICE` が発生するようになりました。

例

例1 mktime() の例

mktime() は入力日付の有効性を確認しており、範囲外の入力を自動的に修正して計算してくれるので便利です。例えば、以下の各行はいずれも文字列 "Jan-01-1998"を出力します。


<?php
echo date("M-d-Y", mktime(0, 0, 0, 12, 32, 1997));
echo date("M-d-Y", mktime(0, 0, 0, 13, 1, 1997));
echo date("M-d-Y", mktime(0, 0, 0, 1, 1, 1998));
echo date("M-d-Y", mktime(0, 0, 0, 1, 1, 98));
?>

例2 次月の最後の日

指定した月の最後の日は次の月の -1 番目の日ではなく、"0" 番目の日として表すことが可能です。以下の例はともに文字列"The last day in Feb 2000 is: 29" を出力します。


<?php
$lastday = mktime(0, 0, 0, 3, 0, 2000);
echo strftime("Last day in Feb 2000 is: %d", $lastday);
$lastday = mktime(0, 0, 0, 4, -31, 2000);
echo strftime("Last day in Feb 2000 is: %d", $lastday);
?>

注意

警告

PHP 5.1.0 より前のバージョンでは、負の値のタイムスタンプは Windows のどのバージョンにおいてもサポートされていませんでした。したがって、年の有効範囲は 1970 年から 2038 年の間のみに限定されていました。

参考

strftime

microtime

Last updated: Fri, 05 Sep 2008

add a note User Contributed Notes
mktime

ooogla at hotmail dot com
02-Sep-2008 07:56


If you want to increment the day based on a variable when using a loop you can use this when you submit a form



1. Establish a start date and end date in two different variables



2. Get the number of days between a date



$ndays = (strtotime($_POST['edate']) - strtotime($_POST['sdate'])) / (60 * 60 * 24);



Then here is the string you slip in your loop



$nextday  = date('Y-m-d', mktime(0, 0, 0, date("m", strtotime($_POST['sdate']))  , date("d", strtotime($_POST['sdate']))+ $count, date("Y", strtotime($_POST['sdate']))));



$count is incremented by the loop.

thomas_corthals at hotmail dot com
13-May-2008 11:34


It seems mktime() doesn't return negative timestamps on Linux systems with a version of glibc <= 2.3.3.

joseph dot andrew dot hughes at gmail dot com
31-Jan-2008 05:58


Just a small thing to think about if you are only trying to pull the month out using mktime and date.  Make sure you place a 1 into day field.  Otherwise you will get incorrect dates when a month is followed by a month with less days when the day of the current month is higher then the max day of the month you are trying to find.. (Such as today being Jan 30th and trying to find the month Feb.)

PHPcoder at freemail dot ig3 dot net
07-Sep-2007 02:58


The maximum possible date accepted by mktime() and gmmktime() is dependent on the current location time zone.



For example, the 32-bit timestamp overflow occurs at 2038-01-19T03:14:08+0000Z.  But if you're in a UTC -0500 time zone (such as EST in North America), the maximum accepted time before overflow (for older PHP versions on Windows) is 2038-01-18T22:14:07-0500Z, regardless of whether you're passing it to mktime() or gmmktime().

Jonathan Woodard
31-Aug-2007 11:31


NB: one 'gotcha' with the implementation of mktime()'s parameters:



<?php

for( $i = 1 ;  $i <= 12 ; $i++ )

{

    echo "Month '$i' is: " . date( "F" , mktime( 0 , 0 , 0 , $i ) ) . "\n";

}

?>

Will output:

Month '1' is: January

Month '2' is: March

Month '3' is: March

Month '4' is: May

Month '5' is: May

Month '6' is: July

Month '7' is: July

Month '8' is: August

Month '9' is: October

Month '10' is: October

Month '11' is: December

Month '12' is: December

on the 31st day of every month.



Why? Because the 5th parameter "day" defaults to "right now," which will not work reliably for days after the 28th.



To make sure this doesn't happen, specify the first day of the month:

<?php

mktime( 0 , 0 , 0 , $i , 1 )

?>

rlz
17-Jul-2007 01:52


Finding out the number of days in a given month and year, accounting for leap years when February has more than 28 days.





<?php


function days_in_month($year, $month) {


    return( date( "t", mktime( 0, 0, 0, $month, 1, $year) ) );


}


?>





Hope it helps a soul out there.

mike at mike-griffiths dot co dot uk
11-Jul-2007 10:04


It may be useful to note that no E_WARNINGS or E_NOTICES are give if you specify a date <1901 or >2038 on systems where time_t is a 32bit signed integer.



If a date is specified outside of the allowed range you may get some unexpected results as no timestamp will be returned.

rga at merchantpal dot com
01-Apr-2007 01:46


You cannot simply subtract or add month VARs using mktime to obtain previous or next months as suggested in previous user comments (at least not with a DD > 28 anyway).



If the date is 03-31-2007, the following yeilds March as a previous month. Not what you wanted.



<?php

$dateMinusOneMonth = mktime(0, 0, 0, (3-1), 31,  2007 );

$lastmonth = date("n | F", $dateMinusOneMonth);

echo $lastmonth;    //---> 3 | March

?>



mktime correctly gives you back the 3rd of March if you subtract 1 month from March 31 (there are only 28 days in Feb 07).



If you are just looking to do month and year arithmetic using mktime, you can use general days like 1 or 28 to do stuff like this:



<?php

$d_daysinmonth = date('t', mktime(0,0,0,$myMonth,1,$myYear));     // how many days in month

$d_year = date('Y', mktime(0,0,0,$myMonth,1,$myYear));        // year

$d_isleapyear = date('L', mktime(0,0,0,$myMonth,1,$myYear));    // is YYYY a leapyear?



$d_firstdow = date('w', mktime(0,0,0,$myMonth,'1',$myYear));     // FIRST falls on what day of week (0-6)

$d_firstname = date('l', mktime(0,0,0,$myMonth,'1',$myYear));     // FIRST falls on what day of week Full Name



$d_month = date('n', mktime(0,0,0,$myMonth,28,$myYear));         // month of year (1-12)

$d_monthname = date('F', mktime(0,0,0,$myMonth,28,$myYear));         // Month Long name (July)

$d_month_previous = date('n', mktime(0,0,0,($myMonth-1),28,$myYear));         // PREVIOUS month of year (1-12)

$d_monthname_previous = date('F', mktime(0,0,0,($myMonth-1),28,$myYear));     // PREVIOUS Month Long name (July)

$d_month_next = date('n', mktime(0,0,0,($myMonth+1),28,$myYear));         // NEXT month of year (1-12)

$d_monthname_next = date('F', mktime(0,0,0,($myMonth+1),28,$myYear));         // NEXT Month Long name (July)

$d_year_previous = date('Y', mktime(0,0,0,$myMonth,28,($myYear-1)));        // PREVIOUS year

$d_year_next = date('Y', mktime(0,0,0,$myMonth,28,($myYear+1)));        // NEXT year



$d_weeksleft = (52 - $d_weekofyear);                     // how many weeks left in year

$d_daysinyear = $d_isleapyear ? 366 : 365;                // set correct days in year for leap years

$d_daysleft = ($d_daysinyear - $d_dayofyear);                // how many days left in year

?>

Stephen
08-Jan-2007 07:43


There are several warnings here about using mktime() to determine a date difference because of daylight savings time. However, nobody seems to have mentioned the other obvious problem, which is leap years.



Leap years mean that any effort to use mktime() and time() to determine the age (positive or negative) of some timestamp in years will be flawed. There are some years that are 366 days long, therefore you cannot say that there is a set number of seconds per year.



Timestamps are good for determining *real* time, which is not the same thing as *human calendar* time. The Gregorian calendar is only an approximation of real time, which is tweaked with daylight savings time and leap years to make it conform more to humans' expectations of how time should or ought to work. Timestamps are not tweaked and therefore are the only authoritative way of recording in computers a proper order of succession of events, but they cannot be integrated with a Gregorian system unless you take both leap years and DST into account. Otherwise, you may get the wrong number of years when you are approaching a value of exactly X years.



As for PHP, you could still use timestamps as a way of determining age if you took into account not only DST but also whether or not each year is a leap year and adjusted your calculations accordingly. However, this could become messy and inefficient. 



There is an alternative approach to calculating days given the day, month and year of the dates to be compared. Compare the years first, and then compare the month and day - if the month and day have already passed (or, if you like, if they match the current month and day), then add 1 to the total for the years. 



This solution works because it stays within the Gregorian system and doesn't venture into the world of timestamps.



Here is a good discussion of this issue:



http://forums.devshed.com/php-development-5/

need-to-get-the-age-between-dob-

and-today-29925.html?&highlight=age+leap



[the above link was too long; combine the three lines to get the URL]



There is also the issue of leap seconds, but this will only arise if you literally need to get the *exact* age in seconds. In that case, of course, you would also need to verify that your timestamps are exactly correct and are not delayed by script processing time, plus you would need to determine whether your system conforms to UTC, etc. I expect this will hardly be an issue for anybody using PHP, however if you are interested there is an article on this issue on Wikipedia:



http://en.wikipedia.org/wiki/Leap_second

jsebfranck
07-Nov-2006 09:42


There are several notes for mktime which use the number 86400 to differentiate two days. However this technique may pose a problem in case there is a day where the hour change between the two dates to compare.



Consequently, if you want the timestamp difference between the day where the hour change and the next day, it will not be equals to 86400 but either 82800 in case its the winter change of hour day or 90000 for the summer change of hour day.



For example in 2006 :



<?php

echo mktime(0,0,0,10,29,2006) - mktime(0,0,0,10,30,2006); // -90 000

?>

scratch_fury at yahoo dot com
25-Aug-2006 02:07


In response to the post by "nicky" on July 9, 2006:



Just so everyone's clear, if you have a date string formatted in a standard way, you'll probably want to go ahead and use PHP's built-in strtotime() function.  The advantage to using nicky's str2time() function seems to be that you can specify how the date string you're passing in is formatted, so you can deal with non-standard date strings.

carlo dot tafuro at poste dot it
08-May-2006 08:40


Negative timestamps give problem also using linux as guest operating system inside WMvare with Windows host operating system.

colin dot horne at gmail dot com
31-Mar-2005 03:48


If the month is greater than 12, it goes into the next year. If it is less than 1, it goes into the previous year. Generally, it behaves as you'd expect it to :-)



Examples:



<?php



// January 1, 2005

print date ("F j, Y", mktime (0,0,0,13,1,2004));



// December 1, 2003

print date ("F j, Y", mktime (0,0,0,0,1,2004));



// February 1, 2005

print date ("F j, Y", mktime (0,0,0,14,1,2004));



// November 1, 2003

print date ("F j, Y", mktime (0,0,0,-1,1,2004));



?>

Romain Sam
26-Mar-2005 12:50


Under Windows, mktime goes until 2038-01-19 (03:14:07 ...)

joakim stai
29-Mar-2004 03:48


As Nigel pointed out, you should be aware of DST (Daylight Savings Time) when using mktime(). Some systems will return a negative value if you use 0 as the hour, as it will simply skip from (for example) 23:59:59 to 01:00:00. Instead use 12 (noon) as the hour and you won't get a negative timestamp or a date in the 1960's.



This code will work with DST:

$today = mktime(12, 0, 0, date("m"), date("d"), date("Y"));

praas at NOSPAM dot ision dot nl
01-Feb-2004 05:44


Consider skipping months with mktime().



$nextmonth = date("M",mktime(0,0,0,date("n")+1,date("j"),date("Y")));



On any day in Januari you expect to get Feb, right? 

But on January 30th you'll get Mar. It will try Feb 30th, which doesn't exist, and skips another month. Therefore in this case present a day value that will certainly be legal in any month, like day "1".



This will give you next month on any day of the year:

$nextmonth = date("M",mktime(0,0,0,date("n")+1,1,date("Y")));

iain at seatofthepants dot net
09-Dec-2003 12:49


In the above example it should ne boted that if you try to calculate the command at midnight on the 28/04/2004 you will get an erroneous response. This has been driving me to distraction.



$myTime = mktime( 0, 0, 0, 3, 28, 2004);



Solution I found was to create the time at 3am well after the 2am daylight savings problem, viz:



$myTime = mktime( 3, 0, 0, 3, 28, 2004);



Not sure if this is documented anywhere.

trahma
21-Nov-2003 05:06


I think it is important to note that the timestamp returned is based upon the number of seconds from the epoch GMT, and then modified by the time zone settings on the server.



Thus...



mktime(0,0,0,1,1,1970) will not always return 0.  For example with the US eastern time zone (GMT-5) will return 18000 (5 hours past the epoch) and the same function with the time zone set to the US pacific time zone (GMT-8) will return 28800 (8 hours past the epoch).



In an instance where you want time zone independence, you should use the function gmmktime()

laurie at oneuponedown dot com
19-Nov-2003 01:42


With regard to Example 1 and using mktime to correct out-of-range input.





It should be noted that mktime will implement day light saving amends. Consider the following:





<?php


print(date("d/m/Y H:i:s",mktime(0,0,0,3,(27 + 1),2004)));


?>


OUTPUT "28/03/2004 02:00:00"





<?php


print(date("d/m/Y H:i:s",(mktime(0,0,0,3,27,2004) + (((1 * 24) * 60) * 60))));


?>


OUTPUT "28/03/2004 00:00:00"





Dependent on your requirements this may or may be desirable

add a note

strftime

microtime

Last updated: Fri, 05 Sep 2008