strftime() replacement function for PHP 8.1

php-8.1-strftime.php

<?php
namespace PHP81_BC;

/**
 * Locale-formatted strftime using \IntlDateFormatter (PHP 8.1 compatible)
 * This provides a cross-platform alternative to strftime() for when it will be removed from PHP.
 * Note that output can be slightly different between libc sprintf and this function as it is using ICU.
 *
 * Usage:
 * use function \PHP81_BC\strftime;
 * echo strftime('%A %e %B %Y %X', new \DateTime('2021-09-28 00:00:00'), 'fr_FR');
 *
 * Original use:
 * \setlocale('fr_FR.UTF-8', LC_TIME);
 * echo \strftime('%A %e %B %Y %X', strtotime('2021-09-28 00:00:00'));
 *
 * @param  string $format Date format
 * @param  integer|string|DateTime $timestamp Timestamp
 * @return string
 * @author BohwaZ <https://bohwaz.net/>
 */
function strftime(string $format, $timestamp = null, ?string $locale = null): string
{
	if (null === $timestamp) {
		$timestamp = new \DateTime;
	}
	elseif (is_numeric($timestamp)) {
		$timestamp = date_create('@' . $timestamp);

		if ($timestamp) {
			$timestamp->setTimezone(new \DateTimezone(date_default_timezone_get()));
		}
	}
	elseif (is_string($timestamp)) {
		$timestamp = date_create($timestamp);
	}

	if (!($timestamp instanceof \DateTimeInterface)) {
		throw new \InvalidArgumentException('$timestamp argument is neither a valid UNIX timestamp, a valid date-time string or a DateTime object.');
	}

	$locale = substr((string) $locale, 0, 5);

	$intl_formats = [
		'%a' => 'EEE',	// An abbreviated textual representation of the day	Sun through Sat
		'%A' => 'EEEE',	// A full textual representation of the day	Sunday through Saturday
		'%b' => 'MMM',	// Abbreviated month name, based on the locale	Jan through Dec
		'%B' => 'MMMM',	// Full month name, based on the locale	January through December
		'%h' => 'MMM',	// Abbreviated month name, based on the locale (an alias of %b)	Jan through Dec
	];

	$intl_formatter = function (\DateTimeInterface $timestamp, string $format) use ($intl_formats, $locale) {
		$tz = $timestamp->getTimezone();
		$date_type = \IntlDateFormatter::FULL;
		$time_type = \IntlDateFormatter::FULL;
		$pattern = '';

		// %c = Preferred date and time stamp based on locale
		// Example: Tue Feb 5 00:45:10 2009 for February 5, 2009 at 12:45:10 AM
		if ($format == '%c') {
			$date_type = \IntlDateFormatter::LONG;
			$time_type = \IntlDateFormatter::SHORT;
		}
		// %x = Preferred date representation based on locale, without the time
		// Example: 02/05/09 for February 5, 2009
		elseif ($format == '%x') {
			$date_type = \IntlDateFormatter::SHORT;
			$time_type = \IntlDateFormatter::NONE;
		}
		// Localized time format
		elseif ($format == '%X') {
			$date_type = \IntlDateFormatter::NONE;
			$time_type = \IntlDateFormatter::MEDIUM;
		}
		else {
			$pattern = $intl_formats[$format];
		}

		return (new \IntlDateFormatter($locale, $date_type, $time_type, $tz, null, $pattern))->format($timestamp);
	};

	// Same order as https://www.php.net/manual/en/function.strftime.php
	$translation_table = [
		// Day
		'%a' => $intl_formatter,
		'%A' => $intl_formatter,
		'%d' => 'd',
		'%e' => function ($timestamp) {
			return sprintf('% 2u', $timestamp->format('j'));
		},
		'%j' => function ($timestamp) {
			// Day number in year, 001 to 366
			return sprintf('%03d', $timestamp->format('z')+1);
		},
		'%u' => 'N',
		'%w' => 'w',

		// Week
		'%U' => function ($timestamp) {
			// Number of weeks between date and first Sunday of year
			$day = new \DateTime(sprintf('%d-01 Sunday', $timestamp->format('Y')));
			return sprintf('%02u', 1 + ($timestamp->format('z') - $day->format('z')) / 7);
		},
		'%V' => 'W',
		'%W' => function ($timestamp) {
			// Number of weeks between date and first Monday of year
			$day = new \DateTime(sprintf('%d-01 Monday', $timestamp->format('Y')));
			return sprintf('%02u', 1 + ($timestamp->format('z') - $day->format('z')) / 7);
		},

		// Month
		'%b' => $intl_formatter,
		'%B' => $intl_formatter,
		'%h' => $intl_formatter,
		'%m' => 'm',

		// Year
		'%C' => function ($timestamp) {
			// Century (-1): 19 for 20th century
			return floor($timestamp->format('Y') / 100);
		},
		'%g' => function ($timestamp) {
			return substr($timestamp->format('o'), -2);
		},
		'%G' => 'o',
		'%y' => 'y',
		'%Y' => 'Y',

		// Time
		'%H' => 'H',
		'%k' => function ($timestamp) {
			return sprintf('% 2u', $timestamp->format('G'));
		},
		'%I' => 'h',
		'%l' => function ($timestamp) {
			return sprintf('% 2u', $timestamp->format('g'));
		},
		'%M' => 'i',
		'%p' => 'A', // AM PM (this is reversed on purpose!)
		'%P' => 'a', // am pm
		'%r' => 'h:i:s A', // %I:%M:%S %p
		'%R' => 'H:i', // %H:%M
		'%S' => 's',
		'%T' => 'H:i:s', // %H:%M:%S
		'%X' => $intl_formatter, // Preferred time representation based on locale, without the date

		// Timezone
		'%z' => 'O',
		'%Z' => 'T',

		// Time and Date Stamps
		'%c' => $intl_formatter,
		'%D' => 'm/d/Y',
		'%F' => 'Y-m-d',
		'%s' => 'U',
		'%x' => $intl_formatter,
	];

	$out = preg_replace_callback('/(?<!%)(%[a-zA-Z])/', function ($match) use ($translation_table, $timestamp) {
		if ($match[1] == '%n') {
			return "\n";
		}
		elseif ($match[1] == '%t') {
			return "\t";
		}

		if (!isset($translation_table[$match[1]])) {
			throw new \InvalidArgumentException(sprintf('Format "%s" is unknown in time format', $match[1]));
		}

		$replace = $translation_table[$match[1]];

		if (is_string($replace)) {
			return $timestamp->format($replace);
		}
		else {
			return $replace($timestamp, $match[1]);
		}
	}, $format);

	$out = str_replace('%%', '%', $out);
	return $out;
}

Thanks for the function, it works perfectly for my project which lets people reformat date/time on our API output feature

Thanks! Saved me some time updating a crappy legacy project to 8.1

Actually, worked like a charm!

Be warned: This line https://gist.github.com/bohwaz/42fc223031e2b2dd2585aab159a20f30#file-php-8-1-strftime-php-L31 will produce a fatal error in case the date.timezone ini setting is not a valid timezone.

Uncaught Exception: DateTime::__construct(): Invalid date.timezone value 'Afrique/Brazzaville', we selected the timezone 'UTC' for now.

This can happen with cPanel > PHP Selector > Options > date.timezone.

Note though, I have tried to inject an invalid timezone with PHP FPM on my box, but the timezone automatically is reset to UTC.

This can be fixed by, beforehand in your code, adding for example:

	// Fix PHP error if date.timezone ini setting is an invalid timezone identifier.
	date_default_timezone_set( date_default_timezone_get() );

@francoisjacquet thanks. Actually that's the exact same line I'm using in all my PHP code :)

But I don't think it's the role of this snippet to do that kind of stuff.

With php 8.2. i get the error Class "IntlDateFormatter" not found - in ....\thirdparty\time\strftime.php on line: 54 (with php 8.1 it functions)

With php 8.2. i get the error Class "IntlDateFormatter" not found - in ....\thirdparty\time\strftime.php on line: 54 (with php 8.1 it functions)

Just install php8.2-intl :)

No - intl is of course installed . With php 8.1 the code functions.
The Class "IntlDateFormatter is a standard php-class. What helped was to add
use DateTime;
use DateTimeZone;
use DateTimeInterface;
use Exception;
use IntlDateFormatter;
use IntlGregorianCalendar;
use InvalidArgumentException;

You use return sprintf('%02u', 1 + ($timestamp->format('z') - $day->format('z')) / 7);

• Some common mistakes when using sprintf include forgetting to allocate enough space for the output, passing invalid pointers to the function, or providing incorrect format specifiers. These errors can lead to unexpected behavior, such as truncated strings or memory corruption.
  To avoid these issues one should consider using safer alternatives to sprintf, such as the newer snprintf function, which allows to specify the maximum number of characters to write to the output buffer. This helps prevent potential buffer overflow vulnerabilities and ensures that your code behaves predictably.

Example
$a = 123; $b = 456; $c = 789;
$format = '%d + %d + %d = %f';
$values = array($a, $b, $c);
$result = '';
$output_len = snprintf($result, sizeof($result), $format, $values);
if ($output_len >= sizeof($result)) {
echo "Output string truncated! Lost " . ($output_len - sizeof($result) + 1) . " characters.\n";
} else {
printf("%s", $result);
}

What the hell are you talking about, PHP does not have a snprintf function.

Sorry - that was Ai - it assured me that it functions with c++ and php- just delete it.
Perhaps from https://github.com/php/php-src/blob/master/main/snprintf.h or https://opensource.apple.com/source/apache_mod_php/apache_mod_php-131/php/main/snprintf.h.auto.html

Oh for fucks sake, stop making me lose my time with that AI nonsense.

Anyone using AI to report stuff will get blocked from me.

We are smoothly migrating from 7.4 to 8.3 in steps. I love this function, but I’ve added an extra line.
if ( PHP_VERSION_ID < 80100 ) return strftime($format, $timestamp);

strftime was deprecated, among other reasons, because it was inconsistent across platforms:
https://wiki.php.net/rfc/deprecations_php_8_1#strftime_and_gmstrftime

This implementation provides the same functionality but in a consistent manner.

This strftime replacement is maintained in the https://github.com/alphp/strftime repo.

And can be installed using Composer:

composer require php81_bc/strftime

Condicional use:

if ( PHP_VERSION_ID >= 81000 ) {
    use function \PHP81_BC\strftime;
}

Nice, composer! The PHP team tossed the baby out with the bath water on this one.