How to use strftime function in php

<?php教程
echo(strftime("%b %d %Y %X", mktime(20,0,0,12,31,98)));
echo(gmstrftime("%b %d %Y %X", mktime(20,0,0,12,31,98)));

//输出当前日期、时间和时区
echo(gmstrftime("It is %a on %b %d, %Y, %X time zone: %Z",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: &#39;%e%1%&#39; (%%, e, %%, %e, %%)
$format = &#39;%%e%%%e%%&#39;;

// Check for Windows to find and replace the %e 
// modifier correctly
if (strtoupper(substr(PHP_OS, 0, 3)) == &#39;WIN&#39;) {
  $format = preg_replace(&#39;#(?<!%)((?:%%)*)%e#&#39;, &#39;\1%#d&#39;, $format);
}

echo strftime($format);
?>

<?php
// Describe the formats.
$strftimeFormats = array(
  &#39;A&#39; => &#39;A full textual representation of the day&#39;,
  &#39;B&#39; => &#39;Full month name, based on the locale&#39;,
  &#39;C&#39; => &#39;Two digit representation of the century (year pided by 100, truncated to an integer)&#39;,
  &#39;D&#39; => &#39;Same as "%m/%d/%y"&#39;,
  &#39;E&#39; => &#39;&#39;,
  &#39;F&#39; => &#39;Same as "%Y-%m-%d"&#39;,
  &#39;G&#39; => &#39;The full four-digit version of %g&#39;,
  &#39;H&#39; => &#39;Two digit representation of the hour in 24-hour format&#39;,
  &#39;I&#39; => &#39;Two digit representation of the hour in 12-hour format&#39;,
  &#39;J&#39; => &#39;&#39;,
  &#39;K&#39; => &#39;&#39;,
  &#39;L&#39; => &#39;&#39;,
  &#39;M&#39; => &#39;Two digit representation of the minute&#39;,
  &#39;N&#39; => &#39;&#39;,
  &#39;O&#39; => &#39;&#39;,
  &#39;P&#39; => &#39;lower-case "am" or "pm" based on the given time&#39;,
  &#39;Q&#39; => &#39;&#39;,
  &#39;R&#39; => &#39;Same as "%H:%M"&#39;,
  &#39;S&#39; => &#39;Two digit representation of the second&#39;,
  &#39;T&#39; => &#39;Same as "%H:%M:%S"&#39;,
  &#39;U&#39; => &#39;Week number of the given year, starting with the first Sunday as the first week&#39;,
  &#39;V&#39; => &#39;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&#39;,
  &#39;W&#39; => &#39;A numeric representation of the week of the year, starting with the first Monday as the first week&#39;,
  &#39;X&#39; => &#39;Preferred time representation based on locale, without the date&#39;,
  &#39;Y&#39; => &#39;Four digit representation for the year&#39;,
  &#39;Z&#39; => &#39;The time zone offset/abbreviation option NOT given by %z (depends on operating system)&#39;,
  &#39;a&#39; => &#39;An abbreviated textual representation of the day&#39;,
  &#39;b&#39; => &#39;Abbreviated month name, based on the locale&#39;,
  &#39;c&#39; => &#39;Preferred date and time stamp based on local&#39;,
  &#39;d&#39; => &#39;Two-digit day of the month (with leading zeros)&#39;,
  &#39;e&#39; => &#39;Day of the month, with a space preceding single digits&#39;,
  &#39;f&#39; => &#39;&#39;,
  &#39;g&#39; => &#39;Two digit representation of the year going by ISO-8601:1988 standards (see %V)&#39;,
  &#39;h&#39; => &#39;Abbreviated month name, based on the locale (an alias of %b)&#39;,
  &#39;i&#39; => &#39;&#39;,
  &#39;j&#39; => &#39;Day of the year, 3 digits with leading zeros&#39;,
  &#39;k&#39; => &#39;Hour in 24-hour format, with a space preceding single digits&#39;,
  &#39;l&#39; => &#39;Hour in 12-hour format, with a space preceding single digits&#39;,
  &#39;m&#39; => &#39;Two digit representation of the month&#39;,
  &#39;n&#39; => &#39;A newline character ("\n")&#39;,
  &#39;o&#39; => &#39;&#39;,
  &#39;p&#39; => &#39;UPPER-CASE "AM" or "PM" based on the given time&#39;,
  &#39;q&#39; => &#39;&#39;,
  &#39;r&#39; => &#39;Same as "%I:%M:%S %p"&#39;,
  &#39;s&#39; => &#39;Unix Epoch Time timestamp&#39;,
  &#39;t&#39; => &#39;A Tab character ("\t")&#39;,
  &#39;u&#39; => &#39;ISO-8601 numeric representation of the day of the week&#39;,
  &#39;v&#39; => &#39;&#39;,
  &#39;w&#39; => &#39;Numeric representation of the day of the week&#39;,
  &#39;x&#39; => &#39;Preferred date representation based on locale, without the time&#39;,
  &#39;y&#39; => &#39;Two digit representation of the year&#39;,
  &#39;z&#39; => &#39;Either the time zone offset from UTC or the abbreviation (depends on operating system)&#39;,
  &#39;%&#39; => &#39;A literal percentage character ("%")&#39;,
);

// 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(&#39;strlen&#39;, $strftimeValues));

// Report known formats.
foreach($strftimeValues as $format => $value){
  echo "Known format  : &#39;{$format}&#39; = ", str_pad("&#39;{$value}&#39;", $maxValueLength), " ( {$strftimeFormats[$format]} )\n";
}

// Report unknown formats.
foreach(array_diff_key($strftimeFormats, $strftimeValues) as $format => $description){
  echo "Unknown format : &#39;{$format}&#39;  ", str_pad(&#39; &#39;, $maxValueLength), ($description ? " ( {$description} )" : &#39;&#39;), "\n";
}
?>

<?php
echo &#39;本年中的第·&#39; . strftime(&#39;%W&#39;, strtotime(&#39;+2 week midnight -0 second&#39;)) . &#39;·周&#39;;
?>

<?php
echo "現在時間是：" . strftime(&#39;%d.%B %Y %H:%M:%S&#39;, time());
?>

<?php
echo &#39;日期時間格式化為:&#39; . strftime(&#39;%d.%B %Y %H:%M:%S&#39;, strtotime(&#39;2018-10-15&#39;));
?>