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checkdate> <cyrus_unbind
Last updated: Sun, 25 Nov 2007

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Date and Time Functions

Introduktion

These functions allow you to get the date and time from the server where your PHP scripts are running. You can use these functions to format the date and time in many different ways.

Note: Please keep in mind that these functions are dependent on the locale settings of your server. Make sure to take daylight saving time (use e.g. $date = strtotime('+7 days', $date) and not $date += 7*24*60*60) and leap years into consideration when working with these functions.

Note: The timezones referenced in this section can be found in the List of Supported Timezones.

Krav

Inga externa bibliotek behövs för att bygga det tillägg.

Installation

Inga extra installationer behövs för att använda dessa funktioner; de är en del av PHP-kärnan.

Note: The latest version of the timezone database can be installed via PECL's » timezonedb. For Windows users, a pre-compiled DLL can be downloaded from the PECL4Win site: » php_timezonedb.dll.

Konfiguration under drift

De här funktionernas beteende påverkas av inställningarna i php.ini.

Date/Time Configuration Options
Name Default Changeable Changelog
date.default_latitude "31.7667" PHP_INI_ALL Available since PHP 5.0.0.
date.default_longitude "35.2333" PHP_INI_ALL Available since PHP 5.0.0.
date.sunrise_zenith "90.583333" PHP_INI_ALL Available since PHP 5.0.0.
date.sunset_zenith "90.583333" PHP_INI_ALL Available since PHP 5.0.0.
date.timezone "" PHP_INI_ALL Available since PHP 5.1.0.
For further details and definitions of the PHP_INI_* constants, see the php.ini directives.

Här följer en kort förklaring av konfigurationsdirektiven.

date.default_latitude float

The default latitude.

date.default_longitude float

The default longitude.

date.sunrise_zenith float

The default sunrise zenith.

date.sunset_zenith float

The default sunset zenith.

date.timezone string

The default timezone used by all date/time functions if the TZ environment variable isn't set. The precedence order is described in the date_default_timezone_get() page. See List of Supported Timezones for a list of supported timezones.

Note: The first four configuration options are currently only used by date_sunrise() and date_sunset().

Resurstyper

Den här utbyggnaden har inte några resurstyper definerade.

Fördefinerade konstanter

The following constants are defined since PHP 5.1.1 and they offer standard date representations, which can be used along with the date format functions (like date()).

DATE_ATOM (string)
Atom (example: 2005-08-15T15:52:01+00:00)
DATE_COOKIE (string)
HTTP Cookies (example: Monday, 15-Aug-05 15:52:01 UTC)
DATE_ISO8601 (string)
ISO-8601 (example: 2005-08-15T15:52:01+0000)
DATE_RFC822 (string)
RFC 822 (example: Mon, 15 Aug 05 15:52:01 +0000)
DATE_RFC850 (string)
RFC 850 (example: Monday, 15-Aug-05 15:52:01 UTC)
DATE_RFC1036 (string)
RFC 1036 (example: Mon, 15 Aug 05 15:52:01 +0000)
DATE_RFC1123 (string)
RFC 1123 (example: Mon, 15 Aug 2005 15:52:01 +0000)
DATE_RFC2822 (string)
RFC 2822 (Mon, 15 Aug 2005 15:52:01 +0000)
DATE_RFC3339 (string)
Same as DATE_ATOM (since PHP 5.1.3)
DATE_RSS (string)
RSS (Mon, 15 Aug 2005 15:52:01 +0000)
DATE_W3C (string)
World Wide Web Consortium (example: 2005-08-15T15:52:01+00:00)

Following constants exists since PHP 5.1.2 and specify a format returned by functions date_sunrise() and date_sunset().

SUNFUNCS_RET_TIMESTAMP (integer)
Timestamp
SUNFUNCS_RET_STRING (integer)
Hours:minutes (example: 08:02)
SUNFUNCS_RET_DOUBLE (integer)
Hours as floating point number (example 8.75)

Table of Contents



checkdate> <cyrus_unbind
Last updated: Sun, 25 Nov 2007
 
add a note add a note User Contributed Notes
Date/Time
ryan
05-Aug-2008 07:59
Actually in regards to sagar's week functionality, there's a much better way. Well, to at least get the start_timestamp. I'm sure y'all can figure out the end_timestamp on your own. This is part of a script I wrote some time back and uses $_GET['year'] and $_GET['week'] if the user was moving around the calendar. Otherwise it loaded the current week.

Some might ask about January 4th, but according to the official ISO specification or something, January 4th is always in week 1, so it works out.

Oh... and it doesn't work with daylight savings time as well but since it starts on a Monday, for the most part, it won't affect really anything.

<?php
  // Get today
  $date = time();

  // Get times (minute, hour, day) in seconds
  $ms = 1 * 60;
  $hs = 1 * 60 * $ms;
  $ds = 1 * 24 * $hs;

  // Get first day in the week
  if ( is_numeric($_GET['year']) && is_numeric($_GET['week']) )
  {
    $first = strtotime('January 4 '.$_GET['year'].' + '.($_GET['week'] - 1).' weeks');
    $first = $first - $ds * ( date('w', $first) - 1 );
  }
  else
    $first = $date - ( $ds * ( date('w', $date) - 1 ) + $hs * date('H', $date) + $ms * date('i', $date) + date('s', $date) );
?>
Robb_Bean at gmx dot nospam dot net
18-Mar-2008 04:47
With PHP 5.1 and 5.2 the languages datetime support has changed. Although these functions should guess your local timezone settings, they may fail if using a default configuration in a "pre-5.1 way", which means setting no timezone for PHP. In the case PHP could not get a timezone it emits a E_STRICT warning. Note that this affects _all_ datetime functions and keep it in mind when porting software from previous versions to 5.1 or later! It may also confuse your error handling (this is the way I noticed that things have changed, since these changes are not documentated _here_).

References:

http://www.php.net/manual/de/migration51.datetime.php
http://www.php.net/manual/de/migration52.datetime.php
sagar
28-Feb-2008 08:53
<?php
####################################
# Provide week number and get start_timestamp and end_timestamp
#####################################

// this week number will come from the timeshare form
 $week = 51;

$times = get_start_and_end_date_from_week($week);
$start_time = $times['start_timestamp'];
$end_time = $times['end_timestamp'];

function get_start_and_end_date_from_week ($w)
{
    $y = date("Y", time());
    $o = 6; // week starts from sunday by default

    $days = ($w - 1) * 7 + $o;

    $firstdayofyear = getdate(mktime(0,0,0,1,1,$y));
    if ($firstdayofyear["wday"] == 0) $firstdayofyear["wday"] += 7;
    # in getdate, Sunday is 0 instead of 7
    $firstmonday = getdate(mktime(0,0,0,1,1-$firstdayofyear["wday"]+1,$y));
    $calcdate = getdate(mktime(0,0,0,$firstmonday["mon"], $firstmonday["mday"]+$days,$firstmonday["year"]));

    $sday = $calcdate["mday"];
    $smonth = $calcdate["mon"];
    $syear = $calcdate["year"];
   
       
    $timestamp['start_timestamp'] =  mktime(0, 0, 0, $smonth, $sday, $syear);
    $timestamp['end_timestamp'] =  $timestamp['start_timestamp'] + (60*60*24*7);

    return $timestamp;

}    # function datefromweek
?>
nate at example dot com
04-Feb-2008 04:56
Here's my version of date diff that handles leap years, DST, and deals with the diff in terms of "human calculations". For example, this code does not assume that a year = 365.25 days, or that a month = 30/31 days. The results are exactly what a human being would determine as a good result.

<?php

/**
 * this code assumes php >= 5.1.0. if using < 5.1, read
 * php.net/strtotime and change the condition for checking
 * for failure from strtotime()
 */

// $t1, $t2: unix times, or strtotime parseable
// $precision: max number of units to output
// $abbr: if true, use "hr" instead of "hour", etc.
function date_diff ($t1, $t2, $precision = 6, $abbr = false) {
    if (preg_match('/\D/', $t1) && ($t1 = strtotime($t1)) === false)
        return false;

    if (preg_match('/\D/', $t2) && ($t2 = strtotime($t2)) === false)
        return false;

    if ($t1 > $t2)
        list($t1, $t2) = array($t2, $t1);

    $diffs = array(
        'year' => 0, 'month' => 0, 'day' => 0,
        'hour' => 0, 'minute' => 0, 'second' => 0,
    );

    $abbrs = array(
        'year' => 'yr', 'month' => 'mth', 'day' => 'day',
        'hour' => 'hr', 'minute' => 'min', 'second' => 'sec'
    );

    foreach (array_keys($diffs) as $interval) {
        while ($t2 >= ($t3 = strtotime("+1 ${interval}", $t1))) {
            $t1 = $t3;
            ++$diffs[$interval];
        }
    }

    $stack = array();
    foreach ($diffs as $interval => $num)
        $stack[] = array($num, ($abbr ? $abbrs[$interval] : $interval) . ($num != 1 ? 's' : ''));

    $ret = array();
    while (count($ret) < $precision && ($item = array_shift($stack)) !== null) {
        if ($item[0] > 0)
            $ret[] = "{$item[0]} {$item[1]}";
    }

    return implode(', ', $ret);
}

$t1 = 'Feb 4, 2008 12:16:00';
$t2 = 'Jul 3, 2006 16:15:30';

echo date_diff($t1, $t2), "\n",
    date_diff($t1, $t2, 3), "\n",
    date_diff($t1, $t2, 2, true), "\n";

?>
stoicnluv at gmail dot com
05-Nov-2007 03:14
A better and accurate function to calculate the difference between 2 dates. Takes leap years and DST into consideration. Accepts string date or timestamp as arguments.

<?php
function date_diff($d1, $d2){
    $d1 = (is_string($d1) ? strtotime($d1) : $d1);
    $d2 = (is_string($d2) ? strtotime($d2) : $d2);

    $diff_secs = abs($d1 - $d2);
    $base_year = min(date("Y", $d1), date("Y", $d2));

    $diff = mktime(0, 0, $diff_secs, 1, 1, $base_year);
    return array(
        "years" => date("Y", $diff) - $base_year,
        "months_total" => (date("Y", $diff) - $base_year) * 12 + date("n", $diff) - 1,
        "months" => date("n", $diff) - 1,
        "days_total" => floor($diff_secs / (3600 * 24)),
        "days" => date("j", $diff) - 1,
        "hours_total" => floor($diff_secs / 3600),
        "hours" => date("G", $diff),
        "minutes_total" => floor($diff_secs / 60),
        "minutes" => (int) date("i", $diff),
        "seconds_total" => $diff_secs,
        "seconds" => (int) date("s", $diff)
    );
}

$a = date_diff("2006-11-01", "2007-11-01");

echo "<pre>";
print_r($a);
echo "</pre>";
?>

This example will output (if your timezone uses US DST):

Array
(
    [years] => 0
    [months_total] => 11
    [months] => 11
    [days_total] => 364
    [days] => 30
    [hours_total] => 8759
    [hours] => 23
    [minutes_total] => 525540
    [minutes] => 0
    [seconds_total] => 31532400
    [seconds] => 0
)

As you can see, the result is not exactly 1 year (less 1 hour) since Nov 1, 2006 is not DST while Nov 1, 2007 is DST.
venoel at rin dot ru
26-Oct-2007 03:33
May be useful for somebody. This function takes on daylight saving time

<?php
Function DateDiff($date1,$date2) {
  $timedifference=$date2-$date1;
  $corr=date("I",$date2)-date("I",$date1);
  $timedifference+=$corr;
  return $timedifference;
}
?>

Example:

<?php
$d1=mktime(2,0,0,10,28,2007);
$d2=mktime(4,0,0,10,28,2007);
$period=DateDiff($d1,$d2);
printf("<br>%s",date("I d.m.Y H:i",$d1));
printf("<br>%u hour",$period/3600);
printf("<br>%s",date("I d.m.Y H:i",$d2));
?>

Getting 2 hour instead 3.
koch.ro
17-Oct-2007 12:42
Not really elegant, but tells you, if your installed timezonedb is the most recent:

<?php
class TestDateTimeTimezonedbVersion extends PHPUnit_Framework_TestCase
{
    public function testTimezonedbIsMostRecent()
    {
        ini_set( 'date.timezone', 'Europe/Berlin' );
        ob_start();                                                                                                       
        phpinfo(INFO_MODULES);
        $info = ob_get_contents();                                                                                        
        ob_end_clean();
        $start = strpos( $info, 'Timezone Database Version' ) + 29;

        $this->assertTrue( FALSE !== $start, 'Seems there is no timezone DB installed' );

        $end   = strpos( $info, "\n", $start );
        $installedVersion = substr( $info, $start, $end - $start );

        exec( 'pecl remote-info timezonedb', &$output );
        $availableVersion = substr( $output[2], 12 );

        $this->assertEquals( $availableVersion, $installedVersion,
        'The installed timezonedb is not actual. Installed: '.$installedVersion
        .' available: '.$availableVersion
        );
    }
}
?>
herbert DOT fischer ATT gEE mail DOT com
11-Oct-2007 01:44
Updating internal's PHP timezone database (5.1.x and 5.2.x)

http://fischer.tecnologia.ws/en/node/1

[editor: Although this does work, it's often easier just to install the pecl timezonedb extension - they should be up-to-date with the latest possible information]
aquatakat at telus dot net
24-Sep-2007 01:25
I wrote a simple script to format a duration in seconds. Give the function some value in seconds and it will return an array.

<?php

function format_duration($seconds) {

    $periods = array(
        'centuries' => 3155692600,
        'decades' => 315569260,
        'years' => 31556926,
        'months' => 2629743,
        'weeks' => 604800,
        'days' => 86400,
        'hours' => 3600,
        'minutes' => 60,
        'seconds' => 1
    );

    $durations = array();

    foreach ($periods as $period => $seconds_in_period) {
        if ($seconds >= $seconds_in_period) {
            $durations[$period] = floor($seconds / $seconds_in_period);
            $seconds -= $durations[$period] * $seconds_in_period;
        }
    }
   
    return $durations;

}

echo format_duration(864);

/*
[minutes] => 14
[seconds] => 24
*/

echo format_duration(3600);

/*
[hours] => 1
*/

echo format_duration(11111111);

/*
[months] => 4
[days] => 6
[hours] => 20
[minutes] => 28
[seconds] => 59
*/

?>
Darren Edwards
06-Sep-2007 08:54
I was looking for a solution where I could return the number of days, hours, Minutes and seconds between two entries in a table.
DATE_DIFF is not running on my mysql server as my provider uses mysql version 4.0.25
Solution was to use to days and std time functions to calculate the difference in one call.
The fields stored in the table(report_table) are
time(00:00:00),
date(0000-00-00) and record(enum) which tells the app the type of log stored. EG start or end of a report.

SELECT
(TO_DAYS( `end`.`date` ) - TO_DAYS( `start`.`date` ))
-
( second( `end`.`time` ) + (minute( `end`.`time` )*60) + (hour( `end`.`time` )*3600)
<
 second( `start`.`time` ) + (minute( `start`.`time` )*60) + (hour( `start`.`time` )*3600))
AS `days` ,
SEC_TO_TIME(
(second( `end`.`time` ) + (minute( `end`.`time` )*60) + (hour( `end`.`time` )*3600) )
-
(second( `start`.`time` ) + (minute( `start`.`time` )*60) + (hour( `start`.`time` )*3600) )
 ) AS `hms`,
`start`.`time` as `start`,
`end`.`time`  as `end`

FROM `report_table` AS `start` , `report_table` AS `end`
AND `start`.`record` = 'Report Begin'
AND `end`.`record` = 'Report End'
LIMIT 1

If there is no end of report then it will not return a result, as you would expect.
Leopoldo A dot Oducado (poducado at comfsm dot fm)
15-Feb-2007 07:50
Here is my function to count the number days, weeks, months, and year. I tried it below 1970 and it works.

<?php
function datecal($date,$return_value)
{
$date = explode("/", $date);
$month_begin = $date[0];
$month_begin_date = $date[1];
$year1 = $date[2];
$month_end = date("n");
$month_end_date = date("j");
$year2 = date("Y");
$days_old = 0;
$years_old = 0;
$months_old = 0;
if($month_begin==12)
{
  $month = 1;
  $year = $year1+1;
}
else
{
  $month = $month_begin+1;
  $year = $year1;
}
$begin_plus_days = cal_days_in_month(CAL_GREGORIAN, $month_begin, $year1) - $month_begin_date;
$end_minus_days = cal_days_in_month(CAL_GREGORIAN, $month_end, $year2) - $month_end_date;
while ($year <= $year2)
{   
     if($year == $year2)
    {
      $days_old = $days_old + cal_days_in_month(CAL_GREGORIAN, $month, $year);    
      if($month < $month_end)
        {
         $months_old = $months_old + 1;   
         $month = $month + 1;
        }
          elseif ($month==$month_end and $month_end_date >= $month_begin_date)
            {
         $year = $year2+1;   
        }
      else
        {   
         $year = $year2+1;   
        }
    }
    else
    {
     $days_old = $days_old + cal_days_in_month(CAL_GREGORIAN, $month, $year);
         if ($month <= 11)
            {
         $month = $month + 1;
         $months_old = $months_old + 1;   
            }
         else
            {
         $month = 1;
         $year = $year + 1;
         $months_old = $months_old + 1;       
            }    
    }
}
$days_old = ($days_old + $begin_plus_days) - $end_minus_days;
if($return_value == "d")
  { return $days_old; }
elseif ($return_value == "w")
  { return intval($days_old/7); }
elseif ($return_value == "m")
  { return $months_old; }
elseif ($return_value == "y")
  { return intval($months_old/12); }
}

echo datecal("08/13/1975","m");
?>
bgold at matrix-consultants dot com
16-Jan-2007 05:08
When debugging code that stores date/time values in a database, you may find yourself wanting to know the date/time that corresponds to a given unix timestamp, or the timestamp for a given date & time.

The following script will do the conversion either way.  If you give it a numeric timestamp, it will display the corresponding date and time.  If you give it a date and time (in almost any standard format), it will display the timestamp.

All conversions are done for your locale/time zone.

<?php
        while (true)
        {
                // Read a line from standard in.
                echo "enter time to convert: ";
                $inline = fgets(STDIN);
                $inline = trim($inline);
                if ($inline == "" || $inline == ".")
                        break;

                // See if the line is a date.
                $pos = strpos($inline, "/");
                if ($pos === false) {
                        // not a date, should be an integer.
                        $date = date("m/d/Y G:i:s", $inline);
                        echo "int2date: $inline -> $date\n";
                } else {
                        $itime = strtotime($inline);
                        echo "date2int: $inline -> $itime\n";
                }
        }
?>
mikeb at tracersinfo dot com
06-Nov-2006 11:27
Another month late on this, but I would amend alex's post to recommend using gmdate() any time you're trying to represent a "delta time", or your local timezone is likely to interfere.

For example, a five minute difference (300 seconds) would appear as follows in New York:

echo date('z:H:i:s', 300);
// 364:19:05:00

echo gmdate('z:H:i:s', 300);
// 0:00:05:00

Thanks for the 'z', though, Alex.  Up until now, I've always been dividing that out -- hadn't found it in the format list.  :-)
alex dot stevenson at t8design dot com
12-Sep-2006 09:50
A few months late on this, but I just saw cepercival at thatMailThatsHot dot com 's post, and think that it may be a bit easier to just use this as opposed to writing it by hand:

date("z:H:i:s", $endTimestamp - $startTimestamp);

Since the timestamps store seconds from the unix epoch, and the unix epoch occured at the very beginning of a year, you can get away with this.

It gets a little trickier to place the years, but it should work fine if you subtract out the number of years date("Y", 0) returns.  This would naturally require two seperate calls to the date function- one to find the year, and one to find the rest of the information.
cepercival at thatMailThatsHot dot com
11-Jul-2006 05:31
Hopefully this may be useful to someone out there!
I wanted a simple function to give me a duration for phone calls using a start timestamp and end timestamp. After finding an understandable example here http://www.brenlei.com/articles/php/dates/dates4.php i cobbled this together:

<?php
function callDuration($dateTimeBegin,$dateTimeEnd) {
      
      $dif=$dateTimeEnd - $dateTimeBegin;

      $hours = floor($dif / 3600);
      $temp_remainder = $dif - ($hours * 3600);
       
      $minutes = floor($temp_remainder / 60);
      $temp_remainder = $temp_remainder - ($minutes * 60);
       
      $seconds = $temp_remainder;
         
      // leading zero's - not bothered about hours
      $min_lead=':';
     if($minutes <=9)
        $min_lead .= '0';
      $sec_lead=':';
     if($seconds <=9)
        $sec_lead .= '0';
       
  // difference/duration returned as Hours:Mins:Secs e.g. 01:29:32

  return $hours.$min_lead.$minutes.$sec_lead.$seconds;
       
       }
?>

obviously it can be easily extended to include days, weeks etc.
Stupidly simple I know but that's how i like it.
andreencinas at yahoo dot com dot br
28-Sep-2005 05:08
<?php
       //function like dateDiff Microsoft
       //not error in year Bissesto

       function dateDiff($interval,$dateTimeBegin,$dateTimeEnd) {
         //Parse about any English textual datetime
         //$dateTimeBegin, $dateTimeEnd

         $dateTimeBegin=strtotime($dateTimeBegin);
         if($dateTimeBegin === -1) {
           return("..begin date Invalid");
         }

         $dateTimeEnd=strtotime($dateTimeEnd);
         if($dateTimeEnd === -1) {
           return("..end date Invalid");
         }

         $dif=$dateTimeEnd - $dateTimeBegin;

         switch($interval) {
           case "s"://seconds
               return($dif);

           case "n"://minutes
               return(floor($dif/60)); //60s=1m

           case "h"://hours
               return(floor($dif/3600)); //3600s=1h

           case "d"://days
               return(floor($dif/86400)); //86400s=1d

           case "ww"://Week
               return(floor($dif/604800)); //604800s=1week=1semana

           case "m": //similar result "m" dateDiff Microsoft
               $monthBegin=(date("Y",$dateTimeBegin)*12)+
                 date("n",$dateTimeBegin);
               $monthEnd=(date("Y",$dateTimeEnd)*12)+
                 date("n",$dateTimeEnd);
               $monthDiff=$monthEnd-$monthBegin;
               return($monthDiff);

           case "yyyy": //similar result "yyyy" dateDiff Microsoft
               return(date("Y",$dateTimeEnd) - date("Y",$dateTimeBegin));

           default:
               return(floor($dif/86400)); //86400s=1d
         }

       }
?>
glashio at xs4all dot nl
27-Sep-2005 12:46
Calculate Sum BusinessDays (Mon till Fri) between two date's :

<?php
function businessdays($begin, $end) {
    $rbegin = is_string($begin) ? strtotime(strval($begin)) : $begin;
    $rend = is_string($end) ? strtotime(strval($end)) : $end;
    if ($rbegin < 0 || $rend < 0)
        return 0;

    $begin = workday($rbegin, TRUE);
    $end = workday($rend, FALSE);

    if ($end < $begin) {
        $end = $begin;
        $begin = $end;
    }

    $difftime = $end - $begin;
    $diffdays = floor($difftime / (24 * 60 * 60)) + 1;

    if ($diffdays < 7) {
        $abegin = getdate($rbegin);
        $aend = getdate($rend);
        if ($diffdays == 1 && ($astart['wday'] == 0 || $astart['wday'] == 6) && ($aend['wday'] == 0 || $aend['wday'] == 6))
            return 0;
        $abegin = getdate($begin);
        $aend = getdate($end);
        $weekends = ($aend['wday'] < $abegin['wday']) ? 1 : 0;
    } else
        $weekends = floor($diffdays / 7);
    return $diffdays - ($weekends * 2);
}

function workday($date, $begindate = TRUE) {
    $adate = getdate($date);
    $day = 24 * 60 * 60;
    if ($adate['wday'] == 0) // Sunday
        $date += $begindate ? $day : -($day * 2);
    elseif ($adate['wday'] == 6) // Saterday
        $date += $begindate ? $day * 2 : -$day;
    return $date;
}
?>
daniel at globalnetstudios dot com
08-Jun-2005 11:49
This dateDiff() function can take in just about any timestamp, including UNIX timestamps and anything that is accepted by strtotime(). It returns an array with the ability to split the result a couple different ways. I built this function to suffice any datediff needs I had. Hope it helps others too.

<?php
  /********* dateDiff() function **********
   * returns Array of Int values for difference between two dates
   * $date1 > $date2 --> positive integers are returned
   * $date1 < $date2 --> negative integers are returned
   *
   * $split recognizes the following:
   *   'yw' = splits up years, weeks and days (default)
   *   'y'  = splits up years and days
   *   'w'  = splits up weeks and days
   *   'd'  = total days
   *
   * examples:
   *   $dif1 = dateDiff() or dateDiff('yw')
   *   $dif2 = dateDiff('y')
   *   $dif3 = dateDiff('w')
   *   $dif4 = dateDiff('d')
   *
   * assuming dateDiff returned 853 days, the above
   * examples would have a print_r output of:
   *   $dif1 == Array( [y] => 2 [w] => 17 [d] => 4 )
   *   $dif2 == Array( [y] => 2 [d] => 123 )
   *   $dif3 == Array( [w] => 121 [d] => 6 )
   *   $dif4 == Array( [d] => 847 )
   *
   * note: [h] (hours), [m] (minutes), [s] (seconds) are always returned as elements of the Array
   */
  function dateDiff($dt1, $dt2, $split='yw') {
    $date1 = (strtotime($dt1) != -1) ? strtotime($dt1) : $dt1;
    $date2 = (strtotime($dt2) != -1) ? strtotime($dt2) : $dt2;
    $dtDiff = $date1 - $date2;
    $totalDays = intval($dtDiff/(24*60*60));
    $totalSecs = $dtDiff-($totalDays*24*60*60);
    $dif['h'] = $h = intval($totalSecs/(60*60));
    $dif['m'] = $m = intval(($totalSecs-($h*60*60))/60);
    $dif['s'] = $totalSecs-($h*60*60)-($m*60);
    // set up array as necessary
    switch($split) {
    case 'yw': # split years-weeks-days
      $dif['y'] = $y = intval($totalDays/365);
      $dif['w'] = $w = intval(($totalDays-($y*365))/7);
      $dif['d'] = $totalDays-($y*365)-($w*7);
      break;
    case 'y': # split years-days
      $dif['y'] = $y = intval($totalDays/365);
      $dif['d'] = $totalDays-($y*365);
      break;
    case 'w': # split weeks-days
      $dif['w'] = $w = intval($totalDays/7);
      $dif['d'] = $totalDays-($w*7);
      break;
    case 'd': # don't split -- total days
      $dif['d'] = $totalDays;
      break;
    default:
      die("Error in dateDiff(). Unrecognized \$split parameter. Valid values are 'yw', 'y', 'w', 'd'. Default is 'yw'.");
    }
    return $dif;
  }
?>
mail at completeideas dot com
06-Jun-2005 01:55
For those who are using pre MYSQL 4.1.1, you can use:

TO_DAYS([Date Value 1])-TO_DAYS([Date Value 2])

For the same result as:

DATEDIFF([Date Value 1],[Date Value 2])
mincklerstraat at softhome dot net
11-Oct-2004 01:43
Before you get too advanced using date functions, be sure also to see the calendar functions at http://www.php.net/manual/en/ref.calendar.php . </