strftime

string strftime ( string $format [, int $timestamp = time() ] )

<?php
setlocale(LC_TIME, "C");
echo strftime("%A");
setlocale(LC_TIME, "fi_FI");
echo strftime(" in Finnish is %A,");
setlocale(LC_TIME, "fr_FR");
echo strftime(" in French %A and");
setlocale(LC_TIME, "de_DE");
echo strftime(" in German %A.\n");
?>

<?php
/*     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";

?>

<?php

// 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);
?>

<?php
// 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' = 'Friday'            ( A full textual representation of the day )
Known format   : 'B' = 'December'          ( Full month name, based on the locale )
Known format   : 'H' = '11'                ( Two digit representation of the hour in 24-hour format )
Known format   : 'I' = '11'                ( Two digit representation of the hour in 12-hour format )
Known format   : 'M' = '24'                ( Two digit representation of the minute )
Known format   : 'S' = '44'                ( Two digit representation of the second )
Known format   : 'U' = '48'                ( Week number of the given year, starting with the first Sunday as the first week )
Known format   : 'W' = '48'                ( A numeric representation of the week of the year, starting with the first Monday as the first week )
Known format   : 'X' = '11:24:44'          ( Preferred time representation based on locale, without the date )
Known format   : 'Y' = '2010'              ( Four digit representation for the year )
Known format   : 'Z' = 'GMT Standard Time' ( The time zone offset/abbreviation option NOT given by %z (depends on operating system) )
Known format   : 'a' = 'Fri'               ( An abbreviated textual representation of the day )
Known format   : 'b' = 'Dec'               ( Abbreviated month name, based on the locale )
Known format   : 'c' = '12/03/10 11:24:44' ( Preferred date and time stamp based on local )
Known format   : 'd' = '03'                ( Two-digit day of the month (with leading zeros) )
Known format   : 'j' = '337'               ( Day of the year, 3 digits with leading zeros )
Known format   : 'm' = '12'                ( Two digit representation of the month )
Known format   : 'p' = 'AM'                ( UPPER-CASE "AM" or "PM" based on the given time )
Known format   : 'w' = '5'                 ( Numeric representation of the day of the week )
Known format   : 'x' = '12/03/10'          ( Preferred date representation based on locale, without the time )
Known format   : 'y' = '10'                ( Two digit representation of the year )
Known format   : 'z' = 'GMT Standard Time' ( Either the time zone offset from UTC or the abbreviation (depends on operating system) )
Known format   : '%' = '%'                 ( A literal percentage character ("%") )
Unknown format : 'C'                       ( Two digit representation of the century (year divided by 100, truncated to an integer) )
Unknown format : 'D'                       ( Same as "%m/%d/%y" )
Unknown format : 'E'
Unknown format : 'F'                       ( Same as "%Y-%m-%d" )
Unknown format : 'G'                       ( The full four-digit version of %g )
Unknown format : 'J'
Unknown format : 'K'
Unknown format : 'L'
Unknown format : 'N'
Unknown format : 'O'
Unknown format : 'P'                       ( lower-case "am" or "pm" based on the given time )
Unknown format : 'Q'
Unknown format : 'R'                       ( Same as "%H:%M" )
Unknown format : 'T'                       ( Same as "%H:%M:%S" )
Unknown format : '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 )
Unknown format : 'e'                       ( Day of the month, with a space preceding single digits )
Unknown format : 'f'
Unknown format : 'g'                       ( Two digit representation of the year going by ISO-8601:1988 standards (see %V) )
Unknown format : 'h'                       ( Abbreviated month name, based on the locale (an alias of %b) )
Unknown format : 'i'
Unknown format : 'k'                       ( Hour in 24-hour format, with a space preceding single digits )
Unknown format : 'l'                       ( Hour in 12-hour format, with a space preceding single digits )
Unknown format : 'n'                       ( A newline character ("\n") )
Unknown format : 'o'
Unknown format : 'q'
Unknown format : 'r'                       ( Same as "%I:%M:%S %p" )
Unknown format : 's'                       ( Unix Epoch Time timestamp )
Unknown format : 't'                       ( A Tab character ("\t") )
Unknown format : 'u'                       ( ISO-8601 numeric representation of the day of the week )
Unknown format : 'v'