Hướng dẫn time manipulation php

date_modify

(PHP 5 >= 5.2.0, PHP 7, PHP 8)

DateTime::modify -- date_modify — Alters the timestamp

Description

Object-oriented style

public DateTime::modify(string $modifier): DateTime|false

Return Values

Returns the modified DateTime object for method chaining or false on failure.

Examples

Example #1 DateTime::modify() example

Object-oriented style

$date = new DateTime('2006-12-12');
$date->modify('+1 day');
echo $date->format('Y-m-d');
?>

Procedural style

$date = date_create('2006-12-12');
date_modify($date, '+1 day');
echo date_format($date, 'Y-m-d');
?>

The above examples will output:

Example #2 Beware when adding or subtracting months

$date = new DateTime('2000-12-31');$date->modify('+1 month');
echo $date->format('Y-m-d') . "\n";$date->modify('+1 month');
echo $date->format('Y-m-d') . "\n";
?>

The above example will output:

See Also

• strtotime() - Parse about any English textual datetime description into a Unix timestamp
• DateTimeImmutable::modify() - Creates a new object with modified timestamp
• DateTime::add() - Modifies a DateTime object, with added amount of days, months, years, hours, minutes and seconds
• DateTime::sub() - Subtracts an amount of days, months, years, hours, minutes and seconds from a DateTime object
• DateTime::setDate() - Sets the date
• DateTime::setISODate() - Sets the ISO date
• DateTime::setTime() - Sets the time
• DateTime::setTimestamp() - Sets the date and time based on an Unix timestamp

(PHP 4, PHP 5, PHP 7, PHP 8)

date — Format a Unix timestamp

Description

date(string $format, ?int $timestamp = null): string

Parameters

Format accepted by DateTimeInterface::format().

The optional timestamp parameter is an int Unix timestamp that defaults to the current local time if timestamp is omitted or null. In other words, it defaults to the value of time().

Return Values

Returns a formatted date string. If a non-numeric value is used for timestamp, false is returned and an E_WARNING level error is emitted.

Errors/Exceptions

Every call to a date/time function will generate a E_WARNING if the time zone is not valid. See also date_default_timezone_set()

Changelog

Examples

Example #1 date() examples

// set the default timezone to use.
date_default_timezone_set('UTC');// Prints something like: Monday
echo date("l");// Prints something like: Monday 8th of August 2005 03:12:46 PM
echo date('l jS \of F Y h:i:s A');// Prints: July 1, 2000 is on a Saturday
echo "July 1, 2000 is on a " . date("l", mktime(0, 0, 0, 7, 1, 2000));/* use the constants in the format parameter */
// prints something like: Wed, 25 Sep 2013 15:28:57 -0700
echo date(DATE_RFC2822);// prints something like: 2000-07-01T00:00:00+00:00
echo date(DATE_ATOM, mktime(0, 0, 0, 7, 1, 2000));
?>

You can prevent a recognized character in the format string from being expanded by escaping it with a preceding backslash. If the character with a backslash is already a special sequence, you may need to also escape the backslash.

Example #2 Escaping characters in date()

// prints something like: Wednesday the 15th
echo date('l \t\h\e jS');
?>

It is possible to use date() and mktime() together to find dates in the future or the past.

Example #3 date() and mktime() example

$tomorrow  = mktime(0, 0, 0, date("m")  , date("d")+1, date("Y"));
$lastmonth = mktime(0, 0, 0, date("m")-1, date("d"),   date("Y"));
$nextyear  = mktime(0, 0, 0, date("m"),   date("d"),   date("Y")+1);
?>

Note:

This can be more reliable than simply adding or subtracting the number of seconds in a day or month to a timestamp because of daylight saving time.

Some examples of date() formatting. Note that you should escape any other characters, as any which currently have a special meaning will produce undesirable results, and other characters may be assigned meaning in future PHP versions. When escaping, be sure to use single quotes to prevent characters like \n from becoming newlines.

Example #4 date() Formatting

// Assuming today is March 10th, 2001, 5:16:18 pm, and that we are in the
// Mountain Standard Time (MST) Time Zone$today = date("F j, Y, g:i a");                 // March 10, 2001, 5:16 pm
$today = date("m.d.y");                         // 03.10.01
$today = date("j, n, Y");                       // 10, 3, 2001
$today = date("Ymd");                           // 20010310
$today = date('h-i-s, j-m-y, it is w Day');     // 05-16-18, 10-03-01, 1631 1618 6 Satpm01
$today = date('\i\t \i\s \t\h\e jS \d\a\y.');   // it is the 10th day.
$today = date("D M j G:i:s T Y");               // Sat Mar 10 17:16:18 MST 2001
$today = date('H:m:s \m \i\s\ \m\o\n\t\h');     // 17:03:18 m is month
$today = date("H:i:s");                         // 17:16:18
$today = date("Y-m-d H:i:s");                   // 2001-03-10 17:16:18 (the MySQL DATETIME format)
?>

To format dates in other languages, IntlDateFormatter::format() can be used instead of date().

Notes

Note:

To generate a timestamp from a string representation of the date, you may be able to use strtotime(). Additionally, some databases have functions to convert their date formats into timestamps (such as MySQL's » UNIX_TIMESTAMP function).

See Also

• DateTimeImmutable::__construct() - Returns new DateTimeImmutable object
• DateTimeInterface::format() - Returns date formatted according to given format
• gmdate() - Format a GMT/UTC date/time
• idate() - Format a local time/date part as integer
• getdate() - Get date/time information
• getlastmod() - Gets time of last page modification
• mktime() - Get Unix timestamp for a date
• IntlDateFormatter::format() - Format the date/time value as a string
• time() - Return current Unix timestamp
• Predefined DateTime Constants