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  • date()

    (PHP 4, PHP 5, PHP 7)

    格式化一个本地时间/日期

    说明

    date(string $format[,int $timestamp]): string

    返回将整数$timestamp按照给定的格式字串而产生的字符串。如果没有给出时间戳则使用本地当前时间。换句话说,$timestamp是可选的,默认值为time()。

    Tip

    自 PHP 5.1.1 起有几个有用的常量可用作标准的日期/时间格式来指定$format参数。

    Tip

    自 PHP 5.1 起在$_SERVER['REQUEST_TIME']中保存了发起该请求时刻的时间戳。

    Note:

    有效的时间戳典型范围是格林威治时间 1901 年 12 月 13 日 20:45:54 到 2038 年 1 月 19 日 03:14:07。(此范围符合 32 位有符号整数的最小值和最大值)。不过在 PHP 5.1 之前此范围在某些系统(如 Windows)中限制为从 1970 年 1 月 1 日到 2038 年 1 月 19 日。

    Note:

    要将字符串表达的时间转换成时间戳,应该使用strtotime()。此外一些数据库有一些函数将其时间格式转换成时间戳(例如 MySQL 的» UNIX_TIMESTAMP函数)。

    格式字串可以识别以下$format参数的字符串
    $format字符说明返回值例子
    ------
    d月份中的第几天,有前导零的 2 位数字0131
    D星期中的第几天,文本表示,3 个字母MonSun
    j月份中的第几天,没有前导零131
    l(“L”的小写字母)星期几,完整的文本格式SundaySaturday
    NISO-8601 格式数字表示的星期中的第几天(PHP 5.1.0 新加)1(表示星期一)到7(表示星期天)
    S每月天数后面的英文后缀,2 个字符stndrd或者th。可以和j一起用
    w星期中的第几天,数字表示0(表示星期天)到6(表示星期六)
    z年份中的第几天0365
    星期------
    WISO-8601 格式年份中的第几周,每周从星期一开始(PHP 4.1.0 新加的)例如:42(当年的第 42 周)
    ------
    F月份,完整的文本格式,例如 January 或者 MarchJanuaryDecember
    m数字表示的月份,有前导零0112
    M三个字母缩写表示的月份JanDec
    n数字表示的月份,没有前导零112
    t指定的月份有几天2831
    ------
    L是否为闰年如果是闰年为1,否则为0
    oISO-8601 格式年份数字。这和Y的值相同,只除了如果 ISO 的星期数(W)属于前一年或下一年,则用那一年。(PHP 5.1.0 新加)Examples:1999or2003
    Y4 位数字完整表示的年份例如:19992003
    y2 位数字表示的年份例如:9903
    时间------
    a小写的上午和下午值ampm
    A大写的上午和下午值AMPM
    BSwatch Internet 标准时000999
    g小时,12 小时格式,没有前导零112
    G小时,24 小时格式,没有前导零023
    h小时,12 小时格式,有前导零0112
    H小时,24 小时格式,有前导零0023
    i有前导零的分钟数0059>
    s秒数,有前导零0059>
    u毫秒(PHP 5.2.2 新加)。需要注意的是date()函数总是返回000000因为它只接受integer参数,而DateTime::format()才支持毫秒。示例:654321
    时区------
    e时区标识(PHP 5.1.0 新加)例如:UTCGMTAtlantic/Azores
    I是否为夏令时如果是夏令时为1,否则为0
    O与格林威治时间相差的小时数例如:+0200
    P与格林威治时间(GMT)的差别,小时和分钟之间有冒号分隔(PHP 5.1.3 新加)例如:+02:00
    T本机所在的时区例如:ESTMDT(【译者注】在 Windows 下为完整文本格式,例如“Eastern Standard Time”,中文版会显示“中国标准时间”)。
    Z时差偏移量的秒数。UTC 西边的时区偏移量总是负的,UTC 东边的时区偏移量总是正的。-4320043200
    完整的日期/时间------
    cISO 8601 格式的日期(PHP 5 新加)2004-02-12T15:19:21+00:00
    rRFC 822 格式的日期例如:Thu, 21 Dec 2000 16:01:07 +0200
    U从 Unix 纪元(January 1 1970 00:00:00 GMT)开始至今的秒数参见time()

    格式字串中不能被识别的字符将原样显示。Z格式在使用gmdate()时总是返回0

    Example #1date()例子

    <?php
    // 设定要用的默认时区。自 PHP 5.1 可用
    date_default_timezone_set('UTC');
    // 输出类似:Monday
    echo date("l");
    // 输出类似:Monday 15th of August 2005 03:12:46 PM
    echo date('l dS \of F Y h:i:s A');
    // 输出:July 1, 2000 is on a Saturday
    echo "July 1, 2000 is on a " . date("l", mktime(0, 0, 0, 7, 1, 2000));
    /* 在格式参数中使用常量 */
    // 输出类似:Wed, 25 Sep 2013 15:28:57 -0700
    echo date(DATE_RFC2822);
    // 输出类似:2000-07-01T00:00:00+00:00
    echo date(DATE_ATOM, mktime(0, 0, 0, 7, 1, 2000));
    ?>
    

    在格式字串中的字符前加上反斜线来转义可以避免它被按照上表解释。如果加上反斜线后的字符本身就是一个特殊序列,那还要转义反斜线。

    date()中转义字符

    <?php
    // prints something like: Wednesday the 15th
    echo date("l \\t\h\e jS");
    ?>
    

    可以把date()和mktime()函数结合使用来得到未来或过去的日期。

    Example #3date()和mktime()例子

    <?php
    $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:

    由于夏令时的缘故,这种方法比简单地在时间戳上加减一天或者一个月的秒数更可靠。

    一些使用date()格式化日期的例子。注意要转义所有其它的字符,因为目前有特殊含义的字符会产生不需要的结果,而其余字符在 PHP 将来的版本中可能会被用上。当转义时,注意用单引号以避免类似n 的字符变成了换行符。

    Example #4date()格式举例

    <?php
    // 假定今天是:March 10th, 2001, 5:16:18 pm
    $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 z ');  // 05-16-17, 10-03-01, 1631 1618 6 Fripm01
    $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 15:16:08 MST 2001
    $today = date('H:m:s \m \i\s\ \m\o\n\t\h');     // 17:03:17 m is month
    $today = date("H:i:s");                         // 17:16:17
    $today = date("Y-m-d H:i:s");                   // 2001-03-10 17:16:18 (MySQL DATETIME 格式)
    ?>
    

    要格式化其它语种的日期,应该用setlocale()和strftime()函数来代替date()

    参见getlastmod(),gmdate(),mktime(),strftime()和time()。

    参数

    $format

    输出的日期string格式。参见下文中的格式化选项。同时,还可以使用预定义日期常量,例如:常量DATE_RSS表示格式化字符串'D, d M Y H:i:s'

    $format参数字符串中可识别下列字符
    $format字符描述返回值示例
    ------
    d一个月中的第几天,有前导 0 的 2 位数字0131
    D3 个字符表示的星期几MonSun
    j一个月中的第几天,无前导 0131
    l(lowercase 'L')星期几,英文全称SundaySaturday
    NISO-8601 规定的数字表示的星期几(PHP 5.1.0 新加)1(表示星期一)到7(表示星期日)
    S一个月中的第几天,带有 2 个字符表示的英语序数词。stndrd或者th。可以和j联合使用。
    w数字表示的星期几0(星期日)到6(星期六)
    z一年中的第几天,从 0 开始计数0365
    ------
    WISO-8601 规范的一年中的第几周,周一视为一周开始。(PHP 4.1.0 新加)示例:42(本年第42周)
    ------
    F月份英文全拼,例如:January 或 MarchJanuaryDecember
    m带有 0 前导的数字表示的月份0112
    M3 个字符表示的月份的英文简拼JanDec
    n月份的数字表示,无前导01through12
    t给定月份中包含多少天2831
    ------
    L是否为闰年如果是闰年,则返回1,反之返回0
    oISO-8601 规范的年份,同Y格式。有一种情况除外:当 ISO 的周数(W)属于前一年或者后一年时,会返回前一年或者后一年的年份数字表达。属于前一年或者后一年时,会返回前一年或者后一年的年份数字表达。(PHP 5.1.0 新加)示例:19992003
    Y4 位数字的年份示例:19992003
    y2 位数字的年份示例:9903
    时间------
    a上午还是下午,2 位小写字符ampm
    A上午还是下午,2 位大写字符AMPM
    B斯沃琪因特网时间000999
    g小时,12时制,无前导0112
    G小时,24时制,无前导0023
    h小时,12时制,有前导 0 的 2 位数字0112
    H小时,24时制,有前导 0 的 2 位数字00through23
    i分钟,有前导 0 的 2 位数字0059
    s秒,有前导 0 的 2 位数字0059
    u毫秒(PHP 5.2.2 新加)示例:654321
    时区------
    e时区标识(PHP 5.1.0 新加)示例:UTC,GMT,Atlantic/Azores
    I(大写字母 i)是否夏令时如果是夏令时则返回1,反之返回0
    O和格林威治时间(GMT)的时差,以小时为单位示例:+0200
    P和格林威治时间(GMT)的时差,包括小时和分钟,小时和分钟之间使用冒号(:)分隔(PHP 5.1.3 新加)示例:+02:00
    T时区缩写示例:EST,MDT...
    Z以秒为单位的时区偏移量。UTC 以西的时区返回负数,UTC 以东的时区返回正数。-4320050400
    完整的日期/时间------
    cISO 8601 日期及时间(PHP 5 新加)2004-02-12T15:19:21+00:00
    r» RFC 2822格式的日期和时间示例:Thu, 21 Dec 2000 16:01:07 +0200
    U自 1970 年 1 月 1 日 0 时 0 分 0 秒(GMT 时间)以来的时间,以秒为单位参见time()

    格式化字符串中的不可识别字符将原样输出。当使用gmdate()函数时,Z格式永远返回0

    Note:

    由于本函数仅接受integer类型的时间戳参数,所以u格式仅在使用date_format()函数并且使用date_create()函数创建时间戳时才是有用的。

    $timestamp

    可选的$timestamp参数是一个integer的 Unix时间戳,如未指定,参数值默认为当前本地时间。也就是说,其值默认为time()的返回值。

    返回值

    返回格式化后的日期时间的字符串表达。如果$timestamp参数不是一个有效数值,则返回FALSE并引发E_WARNING级别的错误。

    错误/异常

    在每次调用日期/时间函数时,如果时区无效则会引发E_NOTICE错误,如果使用系统设定值或TZ环境变量,则会引发E_STRICTE_WARNING消息。参见date_default_timezone_set()。

    更新日志

    版本说明
    5.1.0时间戳的有效取值范围为 GMT 时间的 1901 年 12 月 13 日至 GMT 时间的 2038 年 1 月 19 日。(32 位有符号整数的取值范围)。但是,在 PHP 5.1.0 之前的版本,在某些系统(例如 Windows)上有效取值范围为 1970 年 1 月 1 日至 2038 年 1 月 19 日。
    5.1.0

    现在发布E_STRICTE_NOTICE时区错误。

    5.1.1$format参数标准的可用日期/时间格式常量见:常量

    范例

    Example #5date()函数示例

    <?php
    // 设置默认时区。PHP 5.1 之后版本可用
    date_default_timezone_set('UTC');
    // 输出类似: Monday
    echo date("l");
    // 输出类似:Monday 8th of August 2005 03:12:46 PM
    echo date('l jS \of F Y h:i:s A');
    // 输出:July 1, 2000 is on a Saturday
    echo "July 1, 2000 is on a " . date("l", mktime(0, 0, 0, 7, 1, 2000));
    /* 使用格式常量 */
    // 输出类似: Mon, 15 Aug 2005 15:12:46 UTC
    echo date(DATE_RFC822);
    // 输出类似:2000-07-01T00:00:00+00:00
    echo date(DATE_ATOM, mktime(0, 0, 0, 7, 1, 2000));
    ?>
    

    可以使用反斜线进行转义来阻止函数解析格式字符串中的可识别字符。如果反斜线和要转义的字符连在一起依然是一个有效的字符序列,那么需要对反斜线再次进行转义。

    date()函数中的格式字符串进行转义

    <?php
    // 输出类似: Wednesday the 15th
    echo date('l \t\h\e jS');
    ?>
    

    可以联合使用date()和mktime()函数来构造之前或者之后的日期时间。

    Example #7date()和mktime()联合使用示例

    <?php
    $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:

    由于存在夏令时时间,所以此方案相对于直接在时间戳上加/减秒数要更加可靠。

    date()函数格式化的一些示例。需要注意的是,即使是对于当前来说并不具有特殊含义的字符,也要像对待具有特殊含义的字符那样进行转义,以避免函数返回非预期的值。因为可能在将来的 PHP 版本中,这些字符会被赋予特殊的含义。进行转义的时候,请确保使用单引号,以避免n 被解释为换行符号。

    Example #8date()函数格式化

    <?php
    // 假设今天是 2001 年 3 月 10 日下午 5 点 16 分 18 秒,
    // 并且位于山区标准时间(MST)时区
    $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
    ?>
    

    如果需要将日期时间格式化为其他语言,你应该使用setlocale()和strftime()函数来替代date()函数。

    注释

    Note:

    使用strtotime()函数将一个字符串表达的日期时间转换为时间戳。另外,一些数据库产品也提供了将日期时间格式转换为时间戳的函数。(例如 MySQL 中的» UNIX_TIMESTAMP函数)。

    Tip

    从 PHP 5.1 版本开始,请求的开始时间可以从变量$_SERVER['REQUEST_TIME']中获取。

    参见

    • gmdate() 格式化一个 GMT/UTC 日期/时间
    • idate() 将本地时间日期格式化为整数
    • getdate() 取得日期/时间信息
    • getlastmod() 获取页面最后修改的时间
    • mktime() 取得一个日期的 Unix 时间戳
    • strftime() 根据区域设置格式化本地时间/日期
    • time() 返回当前的 Unix 时间戳
    • strtotime() 将任何字符串的日期时间描述解析为 Unix 时间戳
    • 预定义的日期时间常量
    Things to be aware of when using week numbers with years.
    <?php
    echo date("YW", strtotime("2011-01-07")); // gives 201101
    echo date("YW", strtotime("2011-12-31")); // gives 201152
    echo date("YW", strtotime("2011-01-01")); // gives 201152 too
    ?>
    BUT
    <?php
    echo date("oW", strtotime("2011-01-07")); // gives 201101
    echo date("oW", strtotime("2011-12-31")); // gives 201152
    echo date("oW", strtotime("2011-01-01")); // gives 201052 (Year is different than previous example)
    ?>
    Reason:
    Y is year from the date
    o is ISO-8601 year number
    W is ISO-8601 week number of year
    Conclusion:
    if using 'W' for the week number use 'o' for the year.
    For Microseconds, we can get by following:
    echo date('Ymd His'.substr((string)microtime(), 1, 8).' e');
    Thought, it might be useful to someone !
    Prior to PHP 5.6.23, Relative Formats for the start of the week aligned with PHP's (0=Sunday,6=Saturday). Since 5.6.23, Relative Formats for the start of the week align with ISO-8601 (1=Monday,7=Sunday). (http://php.net/manual/en/datetime.formats.relative.php)
    This can produce different, and seemingly incorrect, results depending on your PHP version and your choice of 'w' or 'N' for the Numeric representation of the day of the week: 
    <?php
    echo "Today is Sun 2 Oct 2016, day ",date('w',strtotime('2016-10-02'))," of this week. "; 
    echo "Day ",date('w',strtotime('2016-10-02 Monday next week'))," of next week is ",date('d M Y',strtotime('2016-10-02 Monday next week')),"<br />";
    echo "Today is Sun 2 Oct 2016, day ",date('N',strtotime('2016-10-02'))," of this week. "; 
    echo "Day ",date('w',strtotime('2016-10-02 Monday next week'))," of next week is ",date('d M Y',strtotime('2016-10-02 Monday next week'));
    ?> 
    Prior to PHP 5.6.23, this results in: 
    Today is Sun 2 Oct 2016, day 0 of this week. Day 1 of next week is 10 Oct 2016
    Today is Sun 2 Oct 2016, day 7 of this week. Day 1 of next week is 10 Oct 2016
    Since PHP 5.6.23, this results in: 
    Today is Sun 2 Oct 2016, day 0 of this week. Day 1 of next week is 03 Oct 2016
    Today is Sun 2 Oct 2016, day 7 of this week. Day 1 of next week is 03 Oct 2016
    For HTML5 datetime-local HTML input controls (http://www.w3.org/TR/html-markup/input.datetime-local.html) use format example: 1996-12-19T16:39:57
    To generate this, escape the 'T', as shown below:
    <?php
    date('Y-m-d\TH:i:s');
    ?>
    
    this how you make an HTML5 <time> tag correctly
    <?php
    echo '<time datetime="'.date('c').'">'.date('Y - m - d').'</time>';
    ?>
    in the "datetime" attribute you should put a machine-readable value which represent time , the best value is a full time/date with ISO 8601 ( date('c') ) ,,, the attr will be hidden from users
    and it doesn't really matter what you put as a shown value to the user,, any date/time format is okay !
    This is very good for SEO especially search engines like Google .
    If timestamp is a string, date converts it to an integer in a possibly unexpected way:
    <?php
    echo (int)'0x10'; //0
    echo intval('0x10'); //0
    echo date('s', '0x10'); //gives 16
    //however, no octal conversion:
    echo date('s', '010'); //gives 10
    ?>
    (PHP 5.6.16)
    It's common for us to overthink the complexity of date/time calculations and underthink the power and flexibility of PHP's built-in functions. Consider http://php.net/manual/en/function.date.php#108613
    <?php
    function get_time_string($seconds)
    {
      return date('H:i:s', strtotime("2000-01-01 + $seconds SECONDS"));
    }
    FYI: there's a list of constants with predefined formats on the DateTime object, for example instead of outputting ISO 8601 dates with:
    <?php
    echo date('c');
    ?>
    or
    <?php
    echo date('Y-m-d\TH:i:sO');
    ?>
    You can use
    <?php
    echo date(DateTime::ISO8601);
    ?>
    instead, which is much easier to read.
    If you have a problem with the different time zone, this is the solution for that.
    <?php
    // first line of PHP
    $defaultTimeZone='UTC';
    if(date_default_timezone_get()!=$defaultTimeZone)) date_default_timezone_set($defaultTimeZone);
    // somewhere in the code
    function _date($format="r", $timestamp=false, $timezone=false)
    {
      $userTimezone = new DateTimeZone(!empty($timezone) ? $timezone : 'GMT');
      $gmtTimezone = new DateTimeZone('GMT');
      $myDateTime = new DateTime(($timestamp!=false?date("r",(int)$timestamp): date("r")), $gmtTimezone);
      $offset = $userTimezone->getOffset($myDateTime);
      return date($format, ($timestamp!=false?(int)$timestamp:$myDateTime->format('U')) + $offset);
    }
    /* Example */
    echo 'System Date/Time: '.date("Y-m-d | h:i:sa").'<br>';
    echo 'New York Date/Time: '._date("Y-m-d | h:i:sa", false, 'America/New_York').'<br>';
    echo 'Belgrade Date/Time: '._date("Y-m-d | h:i:sa", false, 'Europe/Belgrade').'<br>';
    echo 'Belgrade Date/Time: '._date("Y-m-d | h:i:sa", 514640700, 'Europe/Belgrade').'<br>';
    ?>
    This is the best and fastest solution for this problem. Working almost identical to date() function only as a supplement has the time zone option.
    At least in PHP 5.5.38 date('j.n.Y', 2222222222) gives a result of 2.6.2040.
    So date is not longer limited to the minimum and maximum values for a 32-bit signed integer as timestamp.
    One important thing you should remember is that the timestamp value returned by time() is time-zone agnostic and gets the number of seconds since 1 January 1970 at 00:00:00 UTC. This means that at a particular point in time, this function will return the same value in the US, Europe, India, Japan, ...
    date() will format a time-zone agnostic timestamp according to the default timezone set with date_default_timezone_set(...). Local time. If you want to output as UTC time use:
    <?php
    function dateUTC($format, $timestamp = null)
    {
      if ($timestamp === null) $timestamp = time();
      $tz = date_default_timezone_get();
      date_default_timezone_set('UTC');
      $result = date($format, $timestamp);
      date_default_timezone_set($tz);
      return $result;
    }
    />
    The following function will return the date (on the Gregorian calendar) for Orthodox Easter (Pascha). Note that incorrect results will be returned for years less than 1601 or greater than 2399. This is because the Julian calendar (from which the Easter date is calculated) deviates from the Gregorian by one day for each century-year that is NOT a leap-year, i.e. the century is divisible by 4 but not by 10. (In the old Julian reckoning, EVERY 4th year was a leap-year.)
    This algorithm was first proposed by the mathematician/physicist Gauss. Its complexity derives from the fact that the calculation is based on a combination of solar and lunar calendars.
    <?php
    function getOrthodoxEaster($date){
     /*
      Takes any Gregorian date and returns the Gregorian
      date of Orthodox Easter for that year.
     */
     $year = date("Y", $date);
     $r1 = $year % 19;
     $r2 = $year % 4;
     $r3 = $year % 7;
     $ra = 19 * $r1 + 16;
     $r4 = $ra % 30;
     $rb = 2 * $r2 + 4 * $r3 + 6 * $r4;
     $r5 = $rb % 7;
     $rc = $r4 + $r5;
     //Orthodox Easter for this year will fall $rc days after April 3
     return strtotime("3 April $year + $rc days");
    }
    ?>
    
    Note that some formatting options are different from MySQL.
    For example using a 24 hour notation without leading zeros is the option '%G' in PHP but '%k' in MySQL.
    When using dynamically generated date formatting string, be careful to generate the correct options for either PHP or MySQL.
    In order to define leap year you must considre not only that year can be divide by 4!
    The correct alghoritm is:
    if (year is not divisible by 4) then (it is a common year)
    else if (year is not divisible by 100) then (it is a leap year)
    else if (year is not divisible by 400) then (it is a common year)
    else (it is a leap year)
    So the code should look like this:
    if($year%4 == 0 && $year%100 != 0) {
      $leapYear = 1;
    } elseif($year%400 == 0) {
      $leapYear = 1;              
    } else {
      $leapYear = 0;
    }
    Most spreadsheet programs have a rather nice little built-in function called NETWORKDAYS to calculate the number of business days (i.e. Monday-Friday, excluding holidays) between any two given dates. I couldn't find a simple way to do that in PHP, so I threw this together. It replicates the functionality of OpenOffice's NETWORKDAYS function - you give it a start date, an end date, and an array of any holidays you want skipped, and it'll tell you the number of business days (inclusive of the start and end days!) between them.
    I've tested it pretty strenuously but date arithmetic is complicated and there's always the possibility I missed something, so please feel free to check my math.
    The function could certainly be made much more powerful, to allow you to set different days to be ignored (e.g. "skip all Fridays and Saturdays but include Sundays") or to set up dates that should always be skipped (e.g. "skip July 4th in any year, skip the first Monday in September in any year"). But that's a project for another time.
    <?php
    function networkdays($s, $e, $holidays = array()) {
      // If the start and end dates are given in the wrong order, flip them.  
      if ($s > $e)
        return networkdays($e, $s, $holidays);
      // Find the ISO-8601 day of the week for the two dates.
      $sd = date("N", $s);
      $ed = date("N", $e);
      // Find the number of weeks between the dates.
      $w = floor(($e - $s)/(86400*7));  # Divide the difference in the two times by seven days to get the number of weeks.
      if ($ed >= $sd) { $w--; }    # If the end date falls on the same day of the week or a later day of the week than the start date, subtract a week.
      // Calculate net working days.
      $nwd = max(6 - $sd, 0);  # If the start day is Saturday or Sunday, add zero, otherewise add six minus the weekday number.
      $nwd += min($ed, 5);  # If the end day is Saturday or Sunday, add five, otherwise add the weekday number.
      $nwd += $w * 5;    # Add five days for each week in between.
      // Iterate through the array of holidays. For each holiday between the start and end dates that isn't a Saturday or a Sunday, remove one day.
      foreach ($holidays as $h) {
        $h = strtotime($h);
        if ($h > $s && $h < $e && date("N", $h) < 6)
          $nwd--;
      }
      return $nwd;
    }
    $start = strtotime("1 January 2010");
    $end = strtotime("13 December 2010");
    // Add as many holidays as desired.
    $holidays = array();
    $holidays[] = "4 July 2010";      // Falls on a Sunday; doesn't affect count
    $holidays[] = "6 September 2010";    // Falls on a Monday; reduces count by one
    echo networkdays($start, $end, $holidays);  // Returns 246
    ?>
    Or, if you just want to know how many work days there are in any given year, here's a quick function for that one:
    <?php
    function workdaysinyear($y) {
      $j1 = mktime(0,0,0,1,1,$y);
      if (date("L", $j1)) {
        if (date("N", $j1) == 6)
          return 260;
        elseif (date("N", $j1) == 5 or date("N", $j1) == 7)
          return 261;
        else
          return 262;
      }
      else {
        if (date("N", $j1) == 6 or date("N", $j1) == 7)
          return 260;
        else
          return 261;
      }
    }
    ?>
    
    Looks like date('u') is not microseconds, but is positive difference from rest part.
    php > echo (DateTime::createFromFormat('U.u', '-128649659.999998'))->format('Y-m-d H:i:s.u U.u');
    1965-12-03 23:59:01.999998 -128649659.999998
    `U.u` parsed and formatted same, but means not 1965-12-03 23:59:00.000002.
    Other words correct timestamp for example above is (-128649659 + 0.999998). 
    Less confusing format for it is: 
    php > echo DateTime::createFromFormat('U\+0.u', '-128649660+0.000002')->format('Y-m-d H:i:s.u');
    1965-12-03 23:59:00.000002
    Is that bug or feature?
    In order to define leap year you must considre not only that year can be divide by 4!
    The correct alghoritm is:
    if (year is not divisible by 4) then (it is a common year)
    else if (year is not divisible by 100) then (it is a leap year)
    else if (year is not divisible by 400) then (it is a common year)
    else (it is a leap year)
    So the code should look like this:
    if($year%4 == 0 && $year%100 != 0) {
      $leapYear = 1;
    } elseif($year%400 == 0) {
      $leapYear = 1;              
    } else {
      $leapYear = 0;
    }
    In order to define leap year you must considre not only that year can be divide by 4!
    The correct alghoritm is:
    if (year is not divisible by 4) then (it is a common year)
    else if (year is not divisible by 100) then (it is a leap year)
    else if (year is not divisible by 400) then (it is a common year)
    else (it is a leap year)
    So the code should look like this:
    if($year%4 == 0 && $year%100 != 0) {
      $leapYear = 1;
    } elseif($year%400 == 0) {
      $leapYear = 1;              
    } else {
      $leapYear = 0;
    }

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