Date/Time 函数
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PHP手册

mktime

(PHP 4, PHP 5)

mktime — 取得一个日期的 Unix 时间戳

说明

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

根据给出的参数返回 Unix 时间戳。时间戳是一个长整数，包含了从 Unix 纪元（January 1 1970 00:00:00 GMT）到给定时间的秒数。

参数可以从右向左省略，任何省略的参数会被设置成本地日期和时间的当前值。

参数

hour

小时数。

minute

分钟数。

second

秒数（一分钟之内）。

month

月份数。

day

天数。

year

年份数，可以是两位或四位数字，0-69 对应于 2000-2069，70-100 对应于 1970-2000。在如今系统中普遍把 time_t 作为一个 32 位有符号整数的情况下，year 的合法范围是 1901 到 2038 之间，不过此限制自 PHP 5.1.0 起已被克服了。

is_dst

本参数可以设为 1，表示正处于夏时制时间（DST），0 表示不是夏时制，或者 -1（默认值）表示不知道是否是夏时制。如果未知，PHP 会尝试自己搞明白。这可能产生不可预知（但并非不正确）的结果。如果 PHP 运行的系统中启用了 DST 或者 is_dst 设为 1，某些时间是无效的。例如 DST 自 2:00 生效，则所有处于 2:00 到 3:00 之间的时间都无效，mktime() 会返回一个未定义（通常为负）的值。某些系统（例如 Solaris 8）的 DST 在午夜生效，则 DST 生效当天的 0:30 会被计算为前一天的 23:30。

Note:

自 PHP 5.1.0 起，本参数已被废弃。应该使用新的时区处理特性来替代。

返回值

mktime() 根据给出的参数返回 Unix 时间戳。如果参数非法，本函数返回 FALSE（在 PHP 5.1 之前返回 -1）。

更新日志

版本 说明
3.0.10 加入了 is_dst 参数
5.1.0 is_dst 参数被废弃。出错时函数返回 FALSE 而不再是 -1。修正了本函数可以接受年月日参数全为零。

错误/异常

在每 次调用日期/时间函数时，如果时区无效则会引发 E_NOTICE 错误，如果使用系统设定值或 TZ 环境变量，则会引发 E_STRICT 或 E_WARNING 消息。参见 date_default_timezone_set()

更新日志

版本 说明
5.3.0 mktime() now throws E_DEPRECATED notice if the is_dst parameter is used.
5.1.0 The is_dst parameter became deprecated. Made the function return FALSE on error, instead of -1. Fixed the function to accept the year, month and day to be all passed as zero.
5.1.0 When called with no arguments, mktime() throws E_STRICT notice. Use the time() function instead.
5.1.0

现在发布 E_STRICT 和 E_NOTICE 时区错误。

范例

Example #1 mktime() 例子

mktime() 在做日期计算和验证方面很有用，它会自动计算超出范围的输入的正确值。例如下面例子中每一行都会产生字符串 "Jan-01-1998"。

<?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));
?>

Example #2 下个月的最后一天

任何给定月份的最后一天都可以被表示为下个月的第 "0" 天，而不是 -1 天。下面两个例子都会产生字符串 "The last day in Feb 2000 is: 29"。

<?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);
?>

注释

Caution

在 PHP 5.1.0 之前，在任何已知 Windows 版本以及一些其它系统下不支持负的时间戳。因此年份的有效范围限制为 1970 到 2038。

参见

Date/Time 函数
在线手册：中文 英文
PHP手册
PHP手册 - N: 取得一个日期的 Unix 时间戳

用户评论:

info at mypower dot cz (28-Mar-2012 08:17)

for tothpeter at fbi dot hu

07, 08 and 09 are interpreted as octal values. See http://cz.php.net/manual/en/language.types.integer.php

08 and 09 in octal is error.

If you mean decimal numbers, you must write 7,8 and 9. Not 07, 08 and 09.

tothpeter at fbi dot hu (20-Mar-2012 09:52)

using on mac with MAMP

$a=mktime(0,0,0,07,01,2012);
echo date('Y-m-d',$a); // 2012-07-01

$a=mktime(0,0,0,08,01,2012);
echo date('Y-m-d',$a); // 2011-12-01 WTF

$a=mktime(0,0,0,09,01,2012);
echo date('Y-m-d',$a); // 2011-12-01 WTF

$a=mktime(0,0,0,10,01,2012);
echo date('Y-m-d',$a); // 2012-10-01

$a=mktime(0,0,0,07,31,2012);
echo date('Y-m-d',$a); // 2012-07-31

WTF?

gustavo at ci dot eel dot usp dot br (25-Feb-2012 01:16)

There's a mistake in my post below. This is the correct code:

<?php

$lastDay = date("d",mktime (0,0,0,9+1,0,$year));
 $firstWeekDay = @date("w", @mktime(0,0,0,9,1,2012));
 $weekNumber = ($lastDay == 30 && $firstWeekDay == 6 || $lastDay == 31 && $firstWeekDay >= 5) ? 6 : (($lastDay == "28" && $firstWeekDay == "0") ? 4 : 5);

?>

I'm sorry.

gustavo at ci dot eel dot usp dot br (24-Feb-2012 08:23)

Number of the weeks in a determined month

$lastDay = date("d",mktime (0,0,0,$mon+1,0,$year));
$firstWeekDay = @date("w", @mktime(0,0,0,9,1,2012));
$weekNumber = ($lastDay == 30 && $firstWeekDay == 6) || ($lastDay == 31 && $firstWeekDay >= 5) ? 6 : ($lastDay == "28" && $firstWeekDay == "0") ? 4 : 5;

carlosbuz2 at gmail dot com (04-Mar-2011 06:21)

The first date in array is incorrect, to fix it:

function dates_range($date1, $date2)
{
    if ($date1<$date2)
    {
        $dates_range[]=$date1;
        $date1=strtotime($date1);
        $date2=strtotime($date2);
        while ($date1!=$date2)
        {
            $date1=mktime(0, 0, 0, date("m", $date1), date("d", $date1)+1, date("Y", $date1));
            $dates_range[]=date('Y-m-d', $date1);
        }
    }
    return $dates_range;
}

info at microweb dot lt (03-Nov-2010 03:42)

Function to generate array of dates between two dates (date range array)

<?php
function dates_range($date1, $date2)
{
   if ($date1<$date2)
   {
       $dates_range[]=$date1;
       $date1=strtotime($date1);
       $date2=strtotime($date2);
       while ($date1!=$date2)
       {
           $date1=mktime(0, 0, 0, date("m", $date1), date("d", $date1)+1, date("Y", $date1));
           $dates_range[]=date('Y-m-d', $date1);
       }
   }
   return $dates_range;
}

echo '<pre>';
print_r(dates_range('2009-12-25', '2010-01-05'));
echo '</pre>';
?>

[EDIT BY danbrown AT php DOT net: Contains a bugfix submitted by (carlosbuz2 AT gmail DOT com) on 04-MAR-2011, with the following note: The first date in array is incorrect.]

php at wirnhier dot de (02-Nov-2010 05:17)

warning: mktime expects parameter 1 to be long

It could be a string that is given to mktime, so it has to be converted into an int.

mktime((int)$h, (int)$m, (int)$s, (int)$m, (int)$d, (int)$y);

xr714 at yahoo dot com (07-Oct-2010 04:58)

One of the many problems with Daylight Saving Time / Summer Time is the ambiguity when a specified local time value can refer to two different actual times!  This happens when the local time value is within the relapse range caused by the clocks being set back to proper time.  (eg. if the DST/ST bias is +1 hour, and DST/ST terminates at 02:00 local time, a local time value of 01:30 occurs twice in the same day!)

Because the mktime() function only returns one value, it silently chooses whether to return the time-stamp for the first iteration or the second iteration of a specified local time within this critical range.

To get both possible time-stamps for a local time, compatible with any system locale, time zone, and applicable DST/ST rules, the following function can be used:

<?php /*><!--*/
function LocalToUT($LocalYear, $LocalMonth, $LocalMonthDay, $LocalHour24, $LocalMinute, $LocalSecond) {
/* Converts local date/time to Universal Time values.  Returns both
possible UT values when local time value is within relapse range
(due to Daylight Saving Time / Summer Time termination).
Notes:
    Conversion based on TZ and DST/ST rules used by mktime() function.
    UT time-stamps are number of UT seconds since midnight Jan 1, 1970 UTC.
    UT does not have leap seconds; a UT second is "stretched" by 2x duration
to maintain synchronization with UTC when a UTC leap second elapses.
Inputs:    All inputs are numeric; $LocalHour24 is in 24-hour format.
Returns: Array:
    'initial' = UT time-stamp of first occurrence of specified local date/time
    'relapse' = UT time-stamp of second occurrence, when local time relapses upon DST/ST termination
*/
    $UTValue = mktime($LocalHour24, $LocalMinute, $LocalSecond, $LocalMonth, $LocalMonthDay, $LocalYear);
    $ReturnData = array('initial' => $UTValue, 'relapse' => $UTValue);
    //Test for DST/ST transition since prev day
    $Bias = $UTValue - mktime($LocalHour24, $LocalMinute, $LocalSecond, $LocalMonth, $LocalMonthDay - 1, $LocalYear) - 86400;    //(-) = DST/ST commence, (+) = DST/ST terminate
    if ($Bias == 0) {    //No DST/ST transition detected since prev day
        //Test for DST/ST transition up to next day
        $Bias = mktime($LocalHour24, $LocalMinute, $LocalSecond, $LocalMonth, $LocalMonthDay + 1, $LocalYear) - $UTValue - 86400;    //(-) = DST/ST commence, (+) = DST/ST terminate
    }
    if ($Bias > 0) {    //DST/ST termination detected
        if (date('Z', $UTValue) !== date('Z', $UTValue + $Bias)) {    //Local time occurred in relapse range; System assumed 1st iteration
            $ReturnData['relapse'] = $UTValue + $Bias;
        }
        if (date('Z', $UTValue - $Bias) !== date('Z', $UTValue)) {    //Local time occurred in relapse range; System assumed 2nd iteration
            $ReturnData['initial'] = $UTValue - $Bias;
        }
        //Else local time is outside of relapse range
    }    //Else no DST/ST transition, or transition is commencement
    return $ReturnData;
}
/*--></?php */?>

Do not be confused by the start and end tags; The interleaved PHP-comment and HTML-comment delimiters prevent PHP code containing ">" from appearing as literal text when viewing or editing an HTML file with embedded PHP code.

enVide neFelibata (26-Sep-2010 02:34)

I've had this query for an event organizer.

<?php
   $query = "SELECT MAX(dt_atfrom) FROM tb_date LIMIT 1";
   $raw_data = mysql_query($query);
   $maxdate = mysql_result($raw_data,0,0);
?>
It would fetch the 'bigger' date of all of those events.
The problem started when having events in the future.

I'll start to explain.
Imagine you're in '2010' and the biggest event date is '2011-06-05'.
$maxdate will return me the correct data '2011-06-05', yet since I was only needing the year i passed this date through the following function:

<?php
   maxyear = date("Y", mktime($maxdate));
?>

mktime was returning me the actual year for every future event instead of the future year.

I ended up doing the following:

<?php
   $maxyear = substr($maxdate,0,4);
?>

Probably there's a better solution...

tom at chegg dot com (31-Aug-2010 10:01)

I was using the following to get a list of month names.

for ($i=1; $i<13; $i++) {
  echo date('F', mktime(0,0,0,$i) . ",";
}

Normally this outputs -
January,February,March,April,May,June,July,August,
September,October,November,December

However if today's date is the 31st you get instead:
January,March,March,May,May,July,July,August,October,
October,December,December

Why? Because Feb,Apr,June,Sept, and Nov don't have 31 days!

The fix, add the 5th parameter, don't let the day of month default to today's date:

  echo date('F', mktime(0,0,0,$i,1) . ",";

zfowler at unomaha dot edu (16-Mar-2010 10:18)

Proper way to convert Excel dates into PHP-friendly timestamps using mktime():

<?php
// The date 6/30/2009 is stored as 39994 in Excel
$days = 39994;

// But you must subtract 1 to get the correct timestamp
$ts = mktime(0,0,0,1,$days-1,1900);

// So, this would then match Excel's representation:
echo date("m/d/Y",$ts);
?>

Excel uses "number of days since Jan. 1, 1900" to store its dates.  It also treats 1900 as a leap year when it wasn't, thus there is an extra day which must be accounted for in PHP (and the rest of the world).  Subtracting 1 from Excel's number will fix this problem.

contact at phpmember dot com (20-Jan-2010 12:45)

How many days have  passed since the beginning of the year.... regardless of what year it is...

<?php
//Carlos Galindo
//phpmember.com

$days = floor((time()-mktime(null,null,null,1,0,date("Y")))/86400);
           
echo "$days days have passed";

//Good Luck
?>

davix (06-Oct-2009 08:39)

I couldn't find any correct date differentiate function anywhere so I wrote this one which works correctly. It's fully resistant to all troubles with different day count of the month or leap year.
Input must be two timestamps and output is associative array with year, month, day, hour, minute, second items.
It can be used for exact age or similar issues.

<?php
function date_diff($d1, $d2){
/* compares two timestamps and returns array with differencies (year, month, day, hour, minute, second)
*/
  //check higher timestamp and switch if neccessary
  if ($d1 < $d2){
    $temp = $d2;
    $d2 = $d1;
    $d1 = $temp;
  }
  else {
    $temp = $d1; //temp can be used for day count if required
  }
  $d1 = date_parse(date("Y-m-d H:i:s",$d1));
  $d2 = date_parse(date("Y-m-d H:i:s",$d2));
  //seconds
  if ($d1['second'] >= $d2['second']){
    $diff['second'] = $d1['second'] - $d2['second'];
  }
  else {
    $d1['minute']--;
    $diff['second'] = 60-$d2['second']+$d1['second'];
  }
  //minutes
  if ($d1['minute'] >= $d2['minute']){
    $diff['minute'] = $d1['minute'] - $d2['minute'];
  }
  else {
    $d1['hour']--;
    $diff['minute'] = 60-$d2['minute']+$d1['minute'];
  }
  //hours
  if ($d1['hour'] >= $d2['hour']){
    $diff['hour'] = $d1['hour'] - $d2['hour'];
  }
  else {
    $d1['day']--;
    $diff['hour'] = 24-$d2['hour']+$d1['hour'];
  }
  //days
  if ($d1['day'] >= $d2['day']){
    $diff['day'] = $d1['day'] - $d2['day'];
  }
  else {
    $d1['month']--;
    $diff['day'] = date("t",$temp)-$d2['day']+$d1['day'];
  }
  //months
  if ($d1['month'] >= $d2['month']){
    $diff['month'] = $d1['month'] - $d2['month'];
  }
  else {
    $d1['year']--;
    $diff['month'] = 12-$d2['month']+$d1['month'];
  }
  //years
  $diff['year'] = $d1['year'] - $d2['year'];
  return $diff;   
}

$born_date = mktime(6,30,0,7,24,2008);
$date_diff_array = date_diff($born_date, time());
print_r($date_diff_array);
?>

cebleo at n-trance dot net (08-Sep-2009 07:36)

to ADD or SUBSTRACT times NOTE that if you dont specify the UTC zone your result is the difference +- your server UTC delay.

if you are ina utc/GMT +1

<?php
$hours_diff = strtotime("20:00:00")-strtotime("19:00:00");
echo  date('h:i', $hours_diff)." Hours";
?>

it shows: 02:00 Hours

but if you use a default UTC time:

<?php
date_default_timezone_set('UTC');
$hours_diff = strtotime("20:00:00")-strtotime("19:00:00");
echo "<br>". date('h:i', $hours_diff);
?>

it shows: 01:00 Hours.

p2409 at hotmail dot com (02-Aug-2009 04:49)

How to get the first and last dates of the last quarter - useful for things like tax return dates etc.  by Justin

<?php
function getLastQuarter() {
    // Returns an array with a start and end date for the last quarter from todays date
    // eg. If today is 23 Feb 2009, returns $x['start'] = 1 Oct 2008, $x[end] = 31 Dec 2008
    $year = date("Y",mktime());
    $month = date("m",mktime());
    // Formula to get a quarter in the year from a month
    $startmth = $month - 3 - (($month-1) % 3 );
    // Fix up Jan - Feb to get LAST year's quarter dates (Oct - Dec)
    if ($startmth == -2) {
        $startmth+=12;
        $year-=1;
    }
    $endmth = $startmth+2;
    $last_quarter['start'] = mktime(0,0,0,$startmth,1,$year);
    $last_quarter['end'] = mktime(0,0,0,$endmth,date("t",mktime(0,0,0,$endmth,1,$year)),$year);
    return $last_quarter;   
}

// Example - print first and last dates of last quarter.
echo "First day of last quarter was : " . date("d-M-Y",$lastquarter['start']) . "\n";
echo "Last day of last quarter was : " . date("d-M-Y",$lastquarter['end']) . "\n";

// For 2 August 2009, returns:
//    First day of last quarter was : 01-Apr-2009
//    Last day of last quarter was : 30-Jun-2009
//
?>

lucianoiw at hotmail dot com (13-Mar-2009 01:48)

Convert timestamp to time();

<?php
function wp_mktime($_timestamp = ''){
    if($_timestamp){
        $_split_datehour = explode(' ',$_timestamp);
        $_split_data = explode("-", $_split_datehour[0]);
        $_split_hour = explode(":", $_split_datehour[1]);

        return mktime ($_split_hour[0], $_split_hour[1], $_split_hour[2], $_split_data[1], $_split_data[2], $_split_data[0]);
    }
}
?>

[NOTE BY danbrown AT php DOT net: See also (http://php.net/strtotime)]

admin at stipe dot info (16-Feb-2009 10:12)

With combination of mktime and getDate and date() you can add hours / seconds / days / months / years to ANY timestamp. Use strtotime() function to convert any type of dates to timestamp

<?php
    public function addMonthToDate($timeStamp, $totalMonths=1){
        // You can add as many months as you want. mktime will accumulate to the next year.
        $thePHPDate = getdate($timeStamp); // Covert to Array   
        $thePHPDate['mon'] = $thePHPDate['mon']+$totalMonths; // Add to Month   
        $timeStamp = mktime($thePHPDate['hours'], $thePHPDate['minutes'], $thePHPDate['seconds'], $thePHPDate['mon'], $thePHPDate['mday'], $thePHPDate['year']); // Convert back to timestamp
        return $timeStamp;
    }
   
    public function addDayToDate($timeStamp, $totalDays=1){
        // You can add as many days as you want. mktime will accumulate to the next month / year.
        $thePHPDate = getdate($timeStamp);
        $thePHPDate['mday'] = $thePHPDate['mday']+$totalDays;
        $timeStamp = mktime($thePHPDate['hours'], $thePHPDate['minutes'], $thePHPDate['seconds'], $thePHPDate['mon'], $thePHPDate['mday'], $thePHPDate['year']);
        return $timeStamp;
    }

    public function addYearToDate($timeStamp, $totalYears=1){
        $thePHPDate = getdate($timeStamp);
        $thePHPDate['year'] = $thePHPDate['year']+$totalYears;
        $timeStamp = mktime($thePHPDate['hours'], $thePHPDate['minutes'], $thePHPDate['seconds'], $thePHPDate['mon'], $thePHPDate['mday'], $thePHPDate['year']);
        return $timeStamp;
    }
?>

ronnie dot kurniawan at gmail dot com (16-Jan-2009 05:49)

Add (and subtract) unixtime:

<?php
function utime_add($unixtime, $hr=0, $min=0, $sec=0, $mon=0, $day=0, $yr=0) {
  $dt = localtime($unixtime, true);
  $unixnewtime = mktime(
      $dt['tm_hour']+$hr, $dt['tm_min']+$min, $dt['tm_sec']+$sec,
      $dt['tm_mon']+1+$mon, $dt['tm_mday']+$day, $dt['tm_year']+1900+$yr);
  return $unixnewtime;
}
?>

electriic ink (17-Dec-2008 07:30)

Days until Christmas:

<?php
     $time = mktime(0, 0, 0, 12, 25, 2008, 1) - time();

     $days = floor($time/86400);
     $hours = floor(($time-($days*86400))/3600);
     $mins = floor (($time-($days*86400)-($hours*3600))/60);
     $secs = floor ($time-($days*86400)-($hours*3600)-($mins*60));

     $tsecs = $time;
     $thours = round($time/3600);

    
     if ($tsecs <= 600) {

      echo '<html> <head> <title> ' . $tsecs . ' seconds left until 12am Christmas Day </title> <meta http-equiv="refresh" content="1;url=""></head> <body><span

style="font-size:10pt">Christmas day in ' . $days . ' days ' . $hours . ' hours ' .  $mins . ' mins ' . $secs . ' seconds!<br><br>(There are ' . $tsecs . ' seconds in

total)</span></body></html>';
   
     } else {

      echo '<html> <head> <title> ' . $thours . ' hours left until 12am Christmas Day </title> <meta http-equiv="refresh" content="10;url=""></head> <body><span

style="font-size:10pt">Christmas day in ' . $days . ' days ' . $hours . ' hours ' .  $mins . ' mins ' . $secs . ' seconds!<br><br>(There are ' . number_format($thours)

. ' hours in total and ' . number_format($tsecs) . ' seconds in total)</span></body></html>';

     }

?>

Alan (18-Nov-2008 03:52)

Do remember that, counter-intuitively enough, the arguments for month and day are inversed (or middle-endian). A common mistake for Europeans seems to be to feed the date arguments in the expected order (big endian or little endian).

It's clear to see where this weird order comes from (even with the date being big endian the order for all arguments would still be mixed - it's obviously based on the American date format with the time "prefixed" to allow an easier shorthand) and why this wasn't changed (passing the values in the wrong order produces a valid, though unexpected, result in most cases), but it continues to be a source of confusion for me whenever I come back to PHP from other languages or libraries.

Anonymous (14-Nov-2008 04:34)

<?php
//example of functions to know if a date/time value is in summer hour or in winter hour

//====================
function getChgWinDate($dt){
 $y=substr($dt,0,4);
 for($i=31;$i>20;$i--){
  $ts=mktime(3,0,0,10,$i,$y);
  $dy=date('D',$ts);
  if($dy=='Sun') return($y.'/10/'.$i.' 03:00:00');
 }
}
//====================
function getChgSumDate($dt){
 $y=substr($dt,0,4);
 for($i=31;$i>20;$i--){
  $ts=mktime(2,0,0,10,$i,$y);
  $dy=date('D',$ts);
  if($dy=='Sun') return($y.'/03/'.$i.' 02:00:00');
 }
}
//====================
function isSummerDate($dt){
 $b1=getChgWinDate($dt);
 $b2=getChgSumDate($dt);
 if($dt>=$b2&&$dt<$b1) return(true);
 return(false);
}
//====================
function isWinterDate($dt){
 return(!isSummerDate($dt));
}

//====================
$dt = '2008/10/26 03:15:16';
if( isSummerDate($dt) ){
 echo $dt . " is summer hour in france";
}else{
 echo $dt . " is winter hour in france";
}
?>

thebloodyharry at gmail dot com (11-Nov-2008 02:04)

here simple sample for timestamps.(using malaysia GMT 8)

$mkendtimep=mktime(date("H")+8, date("i"), date("s"), date("m"), date("d"), date("Y"));

$todaydate=date("(d/m/y) H:i:s", $mkendtimep);
if (date("l")=="Monday") { $mday=Monday; } else
    if (date("l")=="Tuesday") { $mday=Tuesday; } else
    if (date("l")=="Wednesday") { $mday=Wednesday; } else
    if (date("l")=="Thursday") { $mday=Thursday; } else
    if (date("l")=="Friday") { $mday=Friday; } else
    if (date("l")=="Saturday") { $mday=Saturday; } else
    if (date("l")=="Sunday"){  $mday=Sunday; }

$realtime="$mday$todaydate (GMT +8)";

..hope it will help you out....

yan (10-Nov-2008 01:50)

caculate days between two date

<?php
  // end date is 2008 Oct. 11 00:00:00
  $_endDate = mktime(0,0,0,11,10,2008);
  // begin date is 2007 May 31 13:26:26
  $_beginDate = mktime(13,26,26,05,31,2007);

  $timestamp_diff= $_endDate-$_beginDate +1 ;
  // how many days between those two date
  $days_diff = $timestamp_diff/86400;

?>

Maffu (29-Oct-2008 11:05)

When calling mktime(), be sure that you use values without leading zeros.  The date comes out wrong in the following example:

$endts = mktime(12, 00, 00, 12, 08, 2008, 0);

(note the 08 instead of just 8)

C's scanf() has a format specification where leading 0's can indicate an octal value - perhaps this is related?

mark at markfiend dot com (15-Oct-2008 12:52)

zola at zolaweb:

Your expression date('U', strtotime($mydate)) evaluates to strtotime($mydate). Converting to a UNIX timestamp is what strtotime() does.

ionut dot bodea at eydos dot ro (02-Oct-2008 04:29)

Here is what I use to calculate age. It took me 30 minutes to write and it's quite accurate. What it has special is that it's calculating the number of days a year has (float number), by testing if a year is a leap one or not. This number is used to compute the age.

<?php
function get_age($date_start, $date_end) {
    $t_lived = get_timestamp($date_end) - get_timestamp($date_start);
    $seconds_one_year = get_days_per_year($date_start, $date_end) * 24 * 60 * 60;
    $age = array();
    $age['years_exact'] = $t_lived / $seconds_one_year;
    $age['years'] = floor($t_lived / $seconds_one_year);
    $seconds_remaining = $t_lived % $seconds_one_year;
    $age['days'] = round($seconds_remaining / (24 * 60 * 60));
    return $age;
}
function get_timestamp($date) {
    list($y, $m, $d) = explode('-', $date);
    return mktime(0, 0, 0, $m, $d, $y);
}
function get_days_per_year($date_start, $date_end) {
    list($y1) = explode('-', $date_start);
    list($y2) = explode('-', $date_end);
    $years_days = array();
    for($y = $y1; $y <= $y2; $y++) {
        $years_days[] = date('L', mktime(0, 0, 0, 1, 1, $y)) ? 366 : 365;
    }
    return round(array_sum($years_days) / count($years_days), 2);
}

$date_birth = '1979-10-12';
$date_now = date('Y-m-d');

$age = get_age($date_birth, $date_now);
echo '<pre>';
print_r($age);
echo '</pre>';
?>


It will display something like this:
Array
(
    [years_exact] => 28.972974329491
    [years] => 28
    [days] => 355
)

ooogla at hotmail dot com (01-Sep-2008 11:56)

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 03:34)

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 (30-Jan-2008 08:58)

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 (06-Sep-2007 06:58)

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 03:31)

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 05:52)

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 02:04)

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 (31-Mar-2007 04:46)

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 10:43)

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.

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 12:42)

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
?>

carlo dot tafuro at poste dot it (08-May-2006 12:40)

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 06:48)

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 (25-Mar-2005 03:50)

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

praas at NOSPAM dot ision dot nl (01-Feb-2004 08:44)

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 03:49)

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 (20-Nov-2003 08:06)

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 (18-Nov-2003 04:42)

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