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Date Formats

This page describes the different date formats that the DateTimeImmutable, DateTime, date_create(), date_create_immutable(), and strtotime() parser understands.

Used Symbols
Description Format Examples
daysuf "st" | "nd" | "rd" | "th"  
dd ([0-2]?[0-9] | "3"[01]) daysuf? "7th", "22nd", "31"
DD "0" [0-9] | [1-2][0-9] | "3" [01] "07", "31"
m 'january' | 'february' | 'march' | 'april' | 'may' | 'june' | 'july' | 'august' | 'september' | 'october' | 'november' | 'december' | 'jan' | 'feb' | 'mar' | 'apr' | 'may' | 'jun' | 'jul' | 'aug' | 'sep' | 'sept' | 'oct' | 'nov' | 'dec' | "I" | "II" | "III" | "IV" | "V" | "VI" | "VII" | "VIII" | "IX" | "X" | "XI" | "XII"  
M 'jan' | 'feb' | 'mar' | 'apr' | 'may' | 'jun' | 'jul' | 'aug' | 'sep' | 'sept' | 'oct' | 'nov' | 'dec'  
mm "0"? [0-9] | "1"[0-2] "0", "04", "7", "12"
MM "0" [0-9] | "1"[0-2] "00", "04", "07", "12"
y [0-9]{1,4} "00", "78", "08", "8", "2008"
yy [0-9]{2} "00", "08", "78"
YY [0-9]{4} "2000", "2008", "1978"
Localized Notations
Description Format Examples
American month and day mm "/" dd "5/12", "10/27"
American month, day and year mm "/" dd "/" y "12/22/78", "1/17/2006", "1/17/6"
Four digit year, month and day with slashes YY "/" mm "/" dd "2008/6/30", "1978/12/22"
Four digit year and month (GNU) YY "-" mm "2008-6", "2008-06", "1978-12"
Year, month and day with dashes y "-" mm "-" dd "2008-6-30", "78-12-22", "8-6-21"
Day, month and four digit year, with dots, tabs or dashes dd [.\t-] mm [.-] YY "30-6-2008", "22.12.1978"
Day, month and two digit year, with dots or tabs dd [.\t] mm "." yy "30.6.08", "22\t12.78"
Day, textual month and year dd ([ \t.-])* m ([ \t.-])* y "30-June 2008", "22DEC78", "14 III 1879"
Textual month and four digit year (Day reset to 1) m ([ \t.-])* YY "June 2008", "DEC1978", "March 1879"
Four digit year and textual month (Day reset to 1) YY ([ \t.-])* m "2008 June", "1978-XII", "1879.MArCH"
Textual month, day and year m ([ .\t-])* dd [,.stndrh\t ]+ y "July 1st, 2008", "April 17, 1790", "May.9,78"
Textual month and day m ([ .\t-])* dd [,.stndrh\t ]* "July 1st,", "Apr 17", "May.9"
Day and textual month dd ([ .\t-])* m "1 July", "17 Apr", "9.May"
Month abbreviation, day and year M "-" DD "-" y "May-09-78", "Apr-17-1790"
Year, month abbreviation and day y "-" M "-" DD "78-Dec-22", "1814-MAY-17"
Year (and just the year) YY "1978", "2008"
Textual month (and just the month) m "March", "jun", "DEC"
ISO8601 Notations
Description Format Examples
Eight digit year, month and day YY MM DD "15810726", "19780417", "18140517"
Four digit year, month and day with slashes YY "/" MM "/" DD "2008/06/30", "1978/12/22"
Two digit year, month and day with dashes yy "-" MM "-" DD "08-06-30", "78-12-22"
Four digit year with optional sign, month and day [+-]? YY "-" MM "-" DD "-0002-07-26", "+1978-04-17", "1814-05-17"

Note:

For the y and yy formats, years below 100 are handled in a special way when the y or yy symbol is used. If the year falls in the range 0 (inclusive) to 69 (inclusive), 2000 is added. If the year falls in the range 70 (inclusive) to 99 (inclusive) then 1900 is added. This means that "00-01-01" is interpreted as "2000-01-01".

Note:

The "Day, month and two digit year, with dots or tabs" format (dd [.\t] mm "." yy) only works for the year values 61 (inclusive) to 99 (inclusive) - outside those years the time format "HH [.:] MM [.:] SS" has precedence.

Note:

The "Year (and just the year)" format only works if a time string has already been found -- otherwise this format is recognised as HH MM.

Caution

It is possible to over- and underflow the dd and DD format. Day 0 means the last day of previous month, whereas overflows count into the next month. This makes "2008-08-00" equivalent to "2008-07-31" and "2008-06-31" equivalent to "2008-07-01" (June only has 30 days).

Note that the day range is restricted to 0-31 as indicated by the regular expression above. Thus "2008-06-32" is not a valid date string, for instance.

It is also possible to underflow the mm and MM formats with the value 0. A month value of 0 means December of the previous year. As example "2008-00-22" is equivalent to "2007-12-22".

If you combine the previous two facts and underflow both the day and the month, the following happens: "2008-00-00" first gets converted to "2007-12-00" which then gets converted to "2007-11-30". This also happens with the string "0000-00-00", which gets transformed into "-0001-11-30" (the year -1 in the ISO 8601 calendar, which is 2 BC in the proleptic Gregorian calendar).

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User Contributed Notes 1 note

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aryfilipiak at gmail dot com
4 months ago
The ISO 8601 has the Week Date. I wrote this function. I hope that it can help someone.
If second parameter is not empty it assumes that $a is the year, $b the month and $c the day, and return basic ISO week date: YYYYWwwD (default) or extended: YYYY-Www-D (if $x is true);
If just first parameter is not empty assumes it is a ISO week date (basic or extended), and return  the Unix timestamp.

function ISOwd($a,$b='',$c='',$x=false) {
    if (!$b) {
        if (!preg_match_all('/([0-9]{4})-*W*([0-9]{2})-*([0-9]{1})/', $a, $m, PREG_SET_ORDER))
            return null;
        /* Now year is $m[0][1], week is $m[0][2] and day is $m[0][3] */
        $fd = mktime(0,0,0,1,1,$m[0][1]);  // first day of the first week of the year
        $n  = date('N', $fd);
        /* if ($n==7) $fd=2;  if ($n==6) $fd=3;  if ($n==5) $fd=4;
           if ($n==4) $fd=29; if ($n==3) $fd=30; if ($n==2) $fd=31; if ($n==1) $fd=1; */
        if ($n>4) $fd = mktime(0,0,0,1,9-$n,$m[0][1]);
        elseif ($n>1) $fd = mktime(0,0,0,12,33-$n,$m[0][1]-1);
        return strtotime(date('d-m-Y',$fd).' + '.($m[0][2]-1).' week'.' + '.($m[0][3]-1).' days');
    }
    $f = ($x) ? 'o-\WW-N' : 'o\WWN'; // basic / extended format
    return date($f, mktime(0,0,0,$b,$c,$a));
}
// Example:
echo $test = ISOwd(date('y'),date('m'),date('d'));
echo '<br>';
echo date('y-m-d',ISOwd($test));
echo '<br>';
echo $test = ISOwd(date('y'),date('m'),date('d'),true);
echo '<br>';
echo date('y-m-d',ISOwd($test));
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