strtotime

(PHP 4, PHP 5, PHP 7)

strtotime — Parse about any English textual datetime description into a Unix timestamp

설명

int strtotime ( string $time [, int $now = time() ] )

The function expects to be given a string containing an English date format and will try to parse that format into a Unix timestamp (the number of seconds since January 1 1970 00:00:00 UTC), relative to the timestamp given in now, or the current time if now is not supplied.

Each parameter of this function uses the default time zone unless a time zone is specified in that parameter. Be careful not to use different time zones in each parameter unless that is intended. See date_default_timezone_get() on the various ways to define the default time zone.

인수

time: 날짜/시간 문자열. 유효한 형식은 날짜와 시간 형식에서 설명하고 있습니다.
now: The timestamp which is used as a base for the calculation of relative dates.

반환값

Returns a timestamp on success, FALSE otherwise. Previous to PHP 5.1.0, this function would return -1 on failure.

오류/예외

모든 날짜/시간 함수 호출은 시간대가 유효하지 않을 때 E_NOTICE를, 시스템 설정이나 TZ 환경 변수를 사용할 때 E_STRICT나 E_WARNING 메세지를 생성합니다. date_default_timezone_set()을 참고하십시오.

변경점

버전	설명
5.3.0	Prior to PHP 5.3.0, relative time formats supplied to the `time` argument of strtotime() such as this week, previous week, last week, and next week were interpreted to mean a 7 day period relative to the current date/time, rather than a week period of Monday through Sunday.
5.3.0	Prior to PHP 5.3.0, 24:00 was not a valid format and strtotime() returned `FALSE`.
5.2.7	In PHP 5 prior to 5.2.7, requesting a given occurrence of a given weekday in a month where that weekday was the first day of the month would incorrectly add one week to the returned timestamp. This has been corrected in 5.2.7 and later versions.
5.1.0	Now returns `FALSE` on failure, instead of -1.
5.1.0	시간대 오류시 `E_STRICT`와 `E_NOTICE`가 발생합니다.
5.0.2	In PHP 5 up to 5.0.2, "now" and other relative times are wrongly computed from today's midnight. This differs from other versions where it is correctly computed from current time.
5.0.0	Microseconds began to be allowed, but they are ignored.

예제

Example #1 A strtotime() example


<?php
echo strtotime("now"), "\n";
echo strtotime("10 September 2000"), "\n";
echo strtotime("+1 day"), "\n";
echo strtotime("+1 week"), "\n";
echo strtotime("+1 week 2 days 4 hours 2 seconds"), "\n";
echo strtotime("next Thursday"), "\n";
echo strtotime("last Monday"), "\n";
?>

Example #2 Checking for failure


<?php
$str = 'Not Good';

// previous to PHP 5.1.0 you would compare with -1, instead of false
if (($timestamp = strtotime($str)) === false) {
    echo "The string ($str) is bogus";
} else {
    echo "$str == " . date('l dS \o\f F Y h:i:s A', $timestamp);
}
?>

주의

Note:
If the number of the year is specified in a two digit format, the values between 00-69 are mapped to 2000-2069 and 70-99 to 1970-1999. See the notes below for possible differences on 32bit systems (possible dates might end on 2038-01-19 03:14:07).

Note:
The valid range of a timestamp is typically from Fri, 13 Dec 1901 20:45:54 UTC to Tue, 19 Jan 2038 03:14:07 UTC. (These are the dates that correspond to the minimum and maximum values for a 32-bit signed integer.)

Prior to PHP 5.1.0, not all platforms support negative timestamps, therefore your date range may be limited to no earlier than the Unix epoch. This means that e.g. dates prior to Jan 1, 1970 will not work on Windows, some Linux distributions, and a few other operating systems.

For 64-bit versions of PHP, the valid range of a timestamp is effectively infinite, as 64 bits can represent approximately 293 billion years in either direction.

Note:
Dates in the m/d/y or d-m-y formats are disambiguated by looking at the separator between the various components: if the separator is a slash (/), then the American m/d/y is assumed; whereas if the separator is a dash (-) or a dot (.), then the European d-m-y format is assumed. If, however, the year is given in a two digit format and the separator is a dash (-, the date string is parsed as y-m-d.

To avoid potential ambiguity, it's best to use ISO 8601 (YYYY-MM-DD) dates or DateTime::createFromFormat() when possible.

Note:
Using this function for mathematical operations is not advisable. It is better to use DateTime::add() and DateTime::sub() in PHP 5.3 and later, or DateTime::modify() in PHP 5.2.

참고

Date and Time Formats
DateTime::createFromFormat() - Parses a time string according to a specified format
checkdate() - 그레고리력 날짜를 확인합니다
strptime() - Parse a time/date generated with strftime

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User Contributed Notes 4 notes

down

cesarfrisa at yahoo dot es ¶

1 year ago


This is the link to the relative formats that can be used in this function. It's not easy to find in the documentation.

https://www.php.net/manual/en/datetime.formats.relative.php

Here some examples:
<?php 
$today = date( 'Y-m-d', strtotime( 'today' ) );
echo "Today: " . $today;

// Print: Today: 2023-06-01

//Basic Example 
$tomorrow = date( 'Y-m-d', strtotime( 'tomorrow' ) );
echo "\n\nTomorrow: " . $tomorrow;

// Print: Tomorrow: 2023-06-02

$yesterday = date( 'Y-m-d', strtotime( 'yesterday' ) );
echo "\n\nYesterday: " . $yesterday;

// Print: Yesterday: 2023-05-31

// Add o subtract Month
$variable = date( 'Y-m-d', strtotime( '+1 month' ) );
echo "\n\nAdd one month: " . $variable;

// Print: Add one month: 2023-07-01

$variable = date( 'Y-m-d', strtotime( '-1 month' ) );
echo "\n\nSubstract one month: " . $variable;

// Print: Substract one month: 2023-05-01

// More complex formats:
// ERROR / BUG: If today is the last day of the month. This examples can be one error or bug. 
// If you are looking el first day of previous or next month you dont must use last Relative Format. 
// You must use 'first day of 2 months ago' or 'first day of previous month'
// See you: 
// https://bugs.php.net/bug.php?id=22486
// https://bugs.php.net/bug.php?id=44073
// strtotime("+1 Month")
// produces the wrong result on the 31st day of the month.
// on January 31, date("m",strtotime("+1 Month")) will return 03 instead of 02

// Another example:
$dt1 = strtotime("2023-01-30");
$month = strtotime("+1 month", $dt1);
echo "\n\nToday is: " . date( 'Y-m-d', $dt1 );
echo  "\nBUG add month: " . date("Y-m-d", $month);

// Print:
// Today is: 2023-01-30
// BUG add month: 2023-03-02

$dt1 = strtotime("2023-02-28");
$month = strtotime("-1 month", $dt1);
echo "\n\nToday is: " . date( 'Y-m-d', $dt1 );
echo  "\nBUG substract month: " . date("Y-m-d", $month);

// Print:
// Today is: 2023-02-28
// BUG substract month: 2023-01-28

$dt1 = strtotime("2023-01-30");
$month = strtotime("first day of next month", $dt1);
echo "\n\nToday is: " . date( 'Y-m-d', $dt1 );
echo  "\nFirst day of next month: " . date("Y-m-d", $month);

// Print:
// Today is: 2023-01-30
// First day of next month: 2023-02-01

$dt1 = strtotime("2023-02-28");
$month = strtotime("last day of last month", $dt1);
echo "\n\nToday is: " . date( 'Y-m-d', $dt1 );
echo  "\nLast day of last month: " . date("Y-m-d", $month);

// Print:
// Today is: 2023-02-28
// Last day of last month: 2023-01-31

$dt1 = strtotime("2023-02-28");
$month = strtotime("first day of 2 months ago", $dt1);
echo "\n\nToday is: " . date( 'Y-m-d', $dt1 );
echo  "\nFirst day of 2 months ago: " . date("Y-m-d", $month);

// Print:
// Today is: 2023-02-28
// First day of 2 months ago: 2022-12-01

?>

down

info at pipasjourney dot com ¶

1 year ago


Be aware of this: 1 month before the 31st day, it will return the same month:

<?php
echo date('m', strtotime('2023-05-30 -1 month')) ; //returns 04
echo date('m', strtotime('2023-05-31 -1 month')) ; //returns 05, not 04
?>

So, don't use this to operate on the month of the result.
A better way to know what month was the previous month would be:

<?php
//considering today is 2023-05-31...

$firstOfThisMonth = date('Y-m') . '-01'; //returns 2023-05-01
echo date('m', strtotime($firstOfThisMonth . ' -1 month')) ; //returns 04
?>

down

Vyacheslav Belchuk ¶

1 year ago


Be careful when using two numbers as the year. I came across this situation:

<?php

echo strtotime('24.11.22');
echo date('d.m.Y H:i:s', 1669324282)  .  "\n\n";

// But
echo strtotime('24.11.2022');
echo date('d.m.Y H:i:s', 1669237200);

?>

Output:

1669324282
25.11.2022 00:11:22

1669237200
24.11.2022 00:00:00

down

-5

MarkAgius at markagius dot co dot uk ¶

1 year ago


Note:
If day of month is 12 or less, or year is entered as a two digit number and less than 31 or 12 then you may get the wrong time value.
If you know the format used with the date string, then use the following code: (PHP version 5.5 or later)
[code]
function getStrtotime($timeDateStr, $formatOfStr="j/m/Y"){
  // Same as strtotime() but using the format $formatOfStr.
  // Works with PHP version 5.5 and later.
  // On error reading the time string, returns a date that never existed. 3/09/1752 Julian/Gregorian calendar switch.
  $timeStamp = DateTimeImmutable::createFromFormat($formatOfStr,$timeDateStr);
  if($timeStamp===false){
    // Bad date string or format string.
    return -6858133619; // 3/09/1752
  } else {
    // Date string and format ok.
    return $timeStamp->format("U"); // UNIX timestamp from 1/01/1970,  0:00:00 gmt
  }
}

print date("j/m/Y", getStrtotime("1/02/2022", "j/m/Y"))." Standard format. (j)<BR>\n";
print date("j/m/Y", getStrtotime("1/02/2022", "d/m/Y"))." Standard format. (d)<BR>\n";
print date("j/m/Y", getStrtotime("1/02/2022", "j/m/y"))." Standard format. (y) &lt;-- Bad date as 2022 is not two digits.<BR>\n";
print date("j/m/Y", getStrtotime("21/02/2022", "j/m/Y"))." Standard format. (j)<BR>\n";
print date("j/m/Y", getStrtotime("21/02/2022", "d/m/Y"))." Standard format. (d)<BR>\n";
print date("j/m/Y", getStrtotime("2/01/2022", "m/j/Y"))." US format.<BR>\n";
print date("j/m/Y", getStrtotime("2-01-22", "m-j-y"))." Two digit year, US format. (Y)<BR>\n";
print date("j/m/Y", getStrtotime("2-01-22", "m-j-Y"))." Two digit year, US format. (y) &lt;-- Wrong year if two digits.<BR>\n";
print date("j/m/Y", getStrtotime("3/09/1752", "j/m/Y"))." No such date.<BR>\n";
print date("j/m/Y", getStrtotime("50/00/19999", "j/m/Y"))." Bad date string.<BR>\n";
print date("j/m/Y", getStrtotime("1-02-2022", "j/m/Y"))." Wrong - or / used.<BR>\n";
[/code]
Output:
1/02/2022 Standard format. (j)
1/02/2022 Standard format. (d)
3/09/1752 Standard format. (y) <-- Bad date as 2022 is not two digits.
21/02/2022 Standard format. (j)
21/02/2022 Standard format. (d)
1/02/2022 US format.
1/02/2022 Two digit year, US format. (Y)
1/02/0022 Two digit year, US format. (y) <-- Wrong year if two digits.
3/09/1752 No such date.
3/09/1752 Bad date string.
3/09/1752 Wrong - or / used.

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