strftime

<?

setlocale(LC_TIME, "C");
echo strftime("%A") . PHP_EOL . PHP_EOL;
setlocale(LC_TIME, "fi_FI");
echo strftime("Finnish: %A") . PHP_EOL;
setlocale(LC_TIME, "fr_FR");
echo strftime("French: %A") . PHP_EOL;
setlocale(LC_TIME, "de_DE");
echo strftime("German: %A");

Sunday

Finnish: sunnuntai
French: dimanche
German: Sonntag

<?

/*     December 2002 / January 2003
ISOWk  M   Tu  W   Thu F   Sa  Su
----- ----------------------------
51     16  17  18  19  20  21  22
52     23  24  25  26  27  28  29
1      30  31   1   2   3   4   5
2       6   7   8   9  10  11  12
3      13  14  15  16  17  18  19   */

// Outputs: 12/28/2002 - %V,%G,%Y = 52,2002,2002
echo "12/28/2002 - %V,%G,%Y = " . strftime("%V,%G,%Y", strtotime("12/28/2002")) . "\n";

// Outputs: 12/30/2002 - %V,%G,%Y = 1,2003,2002
echo "12/30/2002 - %V,%G,%Y = " . strftime("%V,%G,%Y", strtotime("12/30/2002")) . "\n";

// Outputs: 1/3/2003 - %V,%G,%Y = 1,2003,2003
echo "1/3/2003 - %V,%G,%Y = " . strftime("%V,%G,%Y",strtotime("1/3/2003")) . "\n";

// Outputs: 1/10/2003 - %V,%G,%Y = 2,2003,2003
echo "1/10/2003 - %V,%G,%Y = " . strftime("%V,%G,%Y",strtotime("1/10/2003")) . "\n";

/*     December 2004 / January 2005
ISOWk  M   Tu  W   Thu F   Sa  Su
----- ----------------------------
51     13  14  15  16  17  18  19
52     20  21  22  23  24  25  26
53     27  28  29  30  31   1   2
1       3   4   5   6   7   8   9
2      10  11  12  13  14  15  16   */

// Outputs: 12/23/2004 - %V,%G,%Y = 52,2004,2004
echo "12/23/2004 - %V,%G,%Y = " . strftime("%V,%G,%Y",strtotime("12/23/2004")) . "\n";

// Outputs: 12/31/2004 - %V,%G,%Y = 53,2004,2004
echo "12/31/2004 - %V,%G,%Y = " . strftime("%V,%G,%Y",strtotime("12/31/2004")) . "\n";

// Outputs: 1/2/2005 - %V,%G,%Y = 53,2004,2005
echo "1/2/2005 - %V,%G,%Y = " . strftime("%V,%G,%Y",strtotime("1/2/2005")) . "\n";

// Outputs: 1/3/2005 - %V,%G,%Y = 1,2005,2005
echo "1/3/2005 - %V,%G,%Y = " . strftime("%V,%G,%Y",strtotime("1/3/2005")) . "\n";

12/28/2002 - %V,%G,%Y = 52,2002,2002
12/30/2002 - %V,%G,%Y = 01,2003,2002
1/3/2003 - %V,%G,%Y = 01,2003,2003
1/10/2003 - %V,%G,%Y = 02,2003,2003
12/23/2004 - %V,%G,%Y = 52,2004,2004
12/31/2004 - %V,%G,%Y = 53,2004,2004
1/2/2005 - %V,%G,%Y = 53,2004,2005
1/3/2005 - %V,%G,%Y = 01,2005,2005

<?

// Jan 1: results in: '%e%1%' (%%, e, %%, %e, %%)
$format = '%%e%%%e%%';

// Check for Windows to find and replace the %e modifier correctly
if (strtoupper(substr(PHP_OS, 0, 3)) == 'WIN') {
    $format = preg_replace('#(?<!%)((?:%%)*)%e#', '\1%#d', $format);
}

echo strftime($format);

%e% 9%

<?

// Describe the formats.
$strftimeFormats = array(
    'A' => 'A full textual representation of the day',
    'B' => 'Full month name, based on the locale',
    'C' => 'Two digit representation of the century (year divided by 100, truncated to an integer)',
    'D' => 'Same as "%m/%d/%y"',
    'E' => '',
    'F' => 'Same as "%Y-%m-%d"',
    'G' => 'The full four-digit version of %g',
    'H' => 'Two digit representation of the hour in 24-hour format',
    'I' => 'Two digit representation of the hour in 12-hour format',
    'J' => '',
    'K' => '',
    'L' => '',
    'M' => 'Two digit representation of the minute',
    'N' => '',
    'O' => '',
    'P' => 'lower-case "am" or "pm" based on the given time',
    'Q' => '',
    'R' => 'Same as "%H:%M"',
    'S' => 'Two digit representation of the second',
    'T' => 'Same as "%H:%M:%S"',
    'U' => 'Week number of the given year, starting with the first Sunday as the first week',
    'V' => 'ISO-8601:1988 week number of the given year, starting with the first week of the year with at least 4 weekdays, with Monday being the start of the week',
    'W' => 'A numeric representation of the week of the year, starting with the first Monday as the first week',
    'X' => 'Preferred time representation based on locale, without the date',
    'Y' => 'Four digit representation for the year',
    'Z' => 'The time zone offset/abbreviation option NOT given by %z (depends on operating system)',
    'a' => 'An abbreviated textual representation of the day',
    'b' => 'Abbreviated month name, based on the locale',
    'c' => 'Preferred date and time stamp based on local',
    'd' => 'Two-digit day of the month (with leading zeros)',
    'e' => 'Day of the month, with a space preceding single digits',
    'f' => '',
    'g' => 'Two digit representation of the year going by ISO-8601:1988 standards (see %V)',
    'h' => 'Abbreviated month name, based on the locale (an alias of %b)',
    'i' => '',
    'j' => 'Day of the year, 3 digits with leading zeros',
    'k' => 'Hour in 24-hour format, with a space preceding single digits',
    'l' => 'Hour in 12-hour format, with a space preceding single digits',
    'm' => 'Two digit representation of the month',
    'n' => 'A newline character ("\n")',
    'o' => '',
    'p' => 'UPPER-CASE "AM" or "PM" based on the given time',
    'q' => '',
    'r' => 'Same as "%I:%M:%S %p"',
    's' => 'Unix Epoch Time timestamp',
    't' => 'A Tab character ("\t")',
    'u' => 'ISO-8601 numeric representation of the day of the week',
    'v' => '',
    'w' => 'Numeric representation of the day of the week',
    'x' => 'Preferred date representation based on locale, without the time',
    'y' => 'Two digit representation of the year',
    'z' => 'Either the time zone offset from UTC or the abbreviation (depends on operating system)',
    '%' => 'A literal percentage character ("%")',
);

// Results.
$strftimeValues = array();

// Evaluate the formats whilst suppressing any errors.
foreach($strftimeFormats as $format => $description){
    if (False !== ($value = @strftime("%{$format}"))){
        $strftimeValues[$format] = $value;
    }
}

// Find the longest value.
$maxValueLength = 2 + max(array_map('strlen', $strftimeValues));

// Report known formats.
foreach($strftimeValues as $format => $value){
    echo "Known format   : '{$format}' = ", str_pad("'{$value}'", $maxValueLength), " ( {$strftimeFormats[$format]} )\n";
}

// Report unknown formats.
foreach(array_diff_key($strftimeFormats, $strftimeValues) as $format => $description){
    echo "Unknown format : '{$format}'   ", str_pad(' ', $maxValueLength), ($description ? " ( {$description} )" : ''), "\n";
}

Known format   : 'A' = 'Sunday'                   ( A full textual representation of the day )
Known format   : 'B' = 'November'                 ( Full month name, based on the locale )
Known format   : 'C' = '20'                       ( Two digit representation of the century (year divided by 100, truncated to an integer) )
Known format   : 'D' = '11/09/25'                 ( Same as "%m/%d/%y" )
Known format   : 'E' = '%E'                       (  )
Known format   : 'F' = '2025-11-09'               ( Same as "%Y-%m-%d" )
Known format   : 'G' = '2025'                     ( The full four-digit version of %g )
Known format   : 'H' = '16'                       ( Two digit representation of the hour in 24-hour format )
Known format   : 'I' = '04'                       ( Two digit representation of the hour in 12-hour format )
Known format   : 'J' = '%J'                       (  )
Known format   : 'K' = '%K'                       (  )
Known format   : 'L' = '%L'                       (  )
Known format   : 'M' = '19'                       ( Two digit representation of the minute )
Known format   : 'N' = '%N'                       (  )
Known format   : 'O' = '%O'                       (  )
Known format   : 'P' = 'pm'                       ( lower-case "am" or "pm" based on the given time )
Known format   : 'Q' = '%Q'                       (  )
Known format   : 'R' = '16:19'                    ( Same as "%H:%M" )
Known format   : 'S' = '53'                       ( Two digit representation of the second )
Known format   : 'T' = '16:19:53'                 ( Same as "%H:%M:%S" )
Known format   : 'U' = '45'                       ( Week number of the given year, starting with the first Sunday as the first week )
Known format   : 'V' = '45'                       ( ISO-8601:1988 week number of the given year, starting with the first week of the year with at least 4 weekdays, with Monday being the start of the week )
Known format   : 'W' = '44'                       ( A numeric representation of the week of the year, starting with the first Monday as the first week )
Known format   : 'X' = '16:19:53'                 ( Preferred time representation based on locale, without the date )
Known format   : 'Y' = '2025'                     ( Four digit representation for the year )
Known format   : 'Z' = 'UTC'                      ( The time zone offset/abbreviation option NOT given by %z (depends on operating system) )
Known format   : 'a' = 'Sun'                      ( An abbreviated textual representation of the day )
Known format   : 'b' = 'Nov'                      ( Abbreviated month name, based on the locale )
Known format   : 'c' = 'Sun Nov  9 16:19:53 2025' ( Preferred date and time stamp based on local )
Known format   : 'd' = '09'                       ( Two-digit day of the month (with leading zeros) )
Known format   : 'e' = ' 9'                       ( Day of the month, with a space preceding single digits )
Known format   : 'f' = '%f'                       (  )
Known format   : 'g' = '25'                       ( Two digit representation of the year going by ISO-8601:1988 standards (see %V) )
Known format   : 'h' = 'Nov'                      ( Abbreviated month name, based on the locale (an alias of %b) )
Known format   : 'i' = '%i'                       (  )
Known format   : 'j' = '313'                      ( Day of the year, 3 digits with leading zeros )
Known format   : 'k' = '16'                       ( Hour in 24-hour format, with a space preceding single digits )
Known format   : 'l' = ' 4'                       ( Hour in 12-hour format, with a space preceding single digits )
Known format   : 'm' = '11'                       ( Two digit representation of the month )
Known format   : 'n' = '
'                        ( A newline character ("\n") )
Known format   : 'o' = '%o'                       (  )
Known format   : 'p' = 'PM'                       ( UPPER-CASE "AM" or "PM" based on the given time )
Known format   : 'q' = '%q'                       (  )
Known format   : 'r' = '04:19:53 PM'              ( Same as "%I:%M:%S %p" )
Known format   : 's' = '1762705193'               ( Unix Epoch Time timestamp )
Known format   : 't' = '    '                        ( A Tab character ("\t") )
Known format   : 'u' = '7'                        ( ISO-8601 numeric representation of the day of the week )
Known format   : 'v' = '%v'                       (  )
Known format   : 'w' = '0'                        ( Numeric representation of the day of the week )
Known format   : 'x' = '11/09/25'                 ( Preferred date representation based on locale, without the time )
Known format   : 'y' = '25'                       ( Two digit representation of the year )
Known format   : 'z' = '+0000'                    ( Either the time zone offset from UTC or the abbreviation (depends on operating system) )
Known format   : '%' = '%'                        ( A literal percentage character ("%") )