PHP: strtotime

Opis

int strtotime ( string czas [, int teraz] )

Funkcja przyjmuje tekst zawierający datę w formacie angielskim i stara się przeliczyć ją na uniksowy znacznik czasu, relatywnie do znacznika czasu podanego w teraz, lub aktualnego czasu, jeśli znacznik nie zostanie podany. W przypadku fiaska, zwracane jest -1.

Ponieważ strtotime() zachowuje się zgodnie ze składnią daty wg GNU, warto zajrzeć do rozdziału podręcznika GNU zatytułowanego Formaty Wprowadzania Daty - Date Input Formats. Opisana tam jest poprawna składnia argumentu czas.

Przykład 1. przykłady strtotime()


<?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";

?>

Przykład 2. Checking for failure


<?php

$str = 'Not Good';

if (($timestamp = strtotime($str)) === -1) {

    echo "Tekst daty ($str) jest niepoprawny";

} else {

    echo "$str == ". date('l dS of F Y h:i:s A',$timestamp);

}

?>

Notatka: Poprawny zakres znacznika czasu to zwykle od piątku, 13 grudnia 1901 20:45:54 GMT (czasu Greenwich) do wtorku, 19 stycznia 2038 03:14:07 GMT. (Wartości te odpowiadają minimalnej i maksymalnej wartości 32-bitowej liczbie całkowitej ze znakiem).

User Contributed Notes


Slight tweak to ScottB's function for UK dates below. Accounts for when a year isn't provided:



function strtotime_uk($str)

{

    $str = preg_replace("/^\s*([0-9]{1,2})[\/\. -]+([0-9]{1,2})[\/\. -]*([0-9]{0,4})/", "\\2/\\1/\\3", $str);

    $str = trim($str,'/');

    echo "Converted to UK date: $str<br>";

    return strtotime($str);

}



As strtotime, if the year isn't provided it will default to current year:



strtotime_uk("13/11"); // 13th November, UK-style


Regarding the previous post on strtotime() being used to convert mysql datetime strings, I agree that this is not widely realized.



Part of the reason for this is that it is only a relatively recent addition. Prior to PHP 5.0, though it might have been an earlier version, strtotime() would return -1 on a mysql datetime string.



If you're on a server that doesn't have a recent PHP version test your result before assuming this one works.


There doesn't seem to be enough documentation about this feature of strtotime(), but it can take a SQL datetime column and convert it to a unix timestamp.



For example:

<?php



$timestamp = strtotime('2006-01-10 16:09:30');

echo($timestamp);



// outputs: 1136930970

?>



This is useful with the Date() Function:

<?php



$timestamp = strtotime('2006-01-10 16:09:30');

echo date('n/j/Y g:i:sa', $timestamp);



// outputs: 1/10/2006 4:09:30pm

?>


I'm posting these here as I believe these to be design changes, not bugs. 



For those upgrading from PHP 4 to PHP 5 there are a number of things that are different about strtotime that I have NOT seen documented elsewhere, or at least not as clearly. I confirmed these with two separate fresh installations of PHP 4.4.1 and PHP 5.1.1. 



1) Given that today is Tuesday: PHP4 "next tuesday" will return today. PHP5 "next tuesday" will actually return next tuesday as in "today +1week". Note that behavior has NOT changed for "last" and "this". For the string "last tuesday" both PHP4 and PHP5 would return "today -1week".  For the string "this tuesday" both PHP4 and PHP5 would return "today". 



2) You cannot include a space immediately following a + or - in PHP 5. In PHP4 the string "today + 1 week" works great. in PHP5 the string must be "today +1 week" to correctly parse. 



3) (Partially noted in changelog.) If you pass php4 a string that is a mess ("asdf1234") it will return -1. If you in turn pass this to date() you'll get a warning like: Windows does not support dates prior to midnight. This is pretty useful for catching errors in your scripts. In PHP 5 strtotime will return FALSE which causes date() to return 12/31/69. Note that this is true of strings that might appear right such as "two weeks". 



4) (Partially noted in changelog.) If you pass php4 an empty string it will error out with a "Notice: strtotime(): Called with empty time parameter". PHP5 will give no notice and return the current date stamp. (A much preferred behavior IMO.) 



5) Some uppercase and mixed-case strings no longer parse correctly. In php4 "Yesterday" would parse correctly. In php5 "Yesterday" will return the infamous 1969 date. This is also true of Tomorrow and Today.



6. The keyword "previous" is supported in PHP5. (Finally!) 



Good luck with your upgrades. :)

 -Will


I have recently had to handle parsing date strings without a year, which broke when the year rolled over.



Assuming the dates will always be in the past, you can use this to fall back to the previous year if the date is too far in the future:



<?php

$data = strtotime("26 dec");

print date("r", $data) . "\n";

if ($data > strtotime("+1 week")) {

  print "Too far in the future\n";

  $data = strtotime("-1 year", $data);

}

print date("r", $data) . "\n";

?>



This outputs:

Tue, 26 Dec 2006 00:00:00 +0000

Too far in the future

Mon, 26 Dec 2005 00:00:00 +0000


Note that by default strtotime( ) considers the string time like a local time.

If your input string time is GMT/UTC do :



<?php

    $date = '2005-12-25 00:56:27 GMT' ; // Note the timezone specification

    $time = strtotime($date) ;

    echo date('d/m/Y H:i:s', $time) ; // $date will be correctly localized

    //