获取一个月的第一个或最后一个星期五

I'm trying to write a calendar function like this

我正在尝试编写这样的日历函数

function get_date($month, $year, $week, $day, $direction)
{
    ....
}

$week is a an integer (1, 2, 3...), $day is a day (Sun, Mon, ...) or number, whichever is easier. The direction is a little confusing, because it does a different calculation.

$ week是一个整数(1,2,3 ......),$ day是一天(太阳,周一,......)或数字,以较容易的为准。方向有点混乱,因为它做了不同的计算。

For an example, let's call

举个例子,我们来电

get_date(5, 2009, 1, 'Sun', 'forward');

get_date(5,2009,1,'Sun','forward');

It uses the default, and gets the first Sunday in May ie 2009-05-03. If we call

它使用默认值,并获得5月的第一个星期日,即2009-05-03。如果我们打电话

get_date(5, 2009, 2, 'Sun', 'backward');

get_date(5,2009,2,'Sun','backward');

, it returns the second last Sunday in May ie 2009-05-24.

,它返回五月的最后一个星期日,即2009-05-24。

12 个解决方案

#1

Perhaps it can be made quicker...
This was VERY interesting to code.

也许它可以更快...这对代码非常有趣。

Please note that $direction is 1 for forward and -1 for backward to ease things up :)
Also, $day begins with a value of 1 for Monday and ends at 7 for Sunday.

请注意,前向的$ direction为1,后向的为-1,以便缓解情况:)此外,$ day的开始值为星期一为1,星期日为7。

function get_date($month, $year, $week, $day, $direction) {
  if($direction > 0)
    $startday = 1;
  else
    $startday = date('t', mktime(0, 0, 0, $month, 1, $year));

  $start = mktime(0, 0, 0, $month, $startday, $year);
  $weekday = date('N', $start);

  if($direction * $day >= $direction * $weekday)
    $offset = -$direction * 7;
  else
    $offset = 0;

  $offset += $direction * ($week * 7) + ($day - $weekday);
  return mktime(0, 0, 0, $month, $startday + $offset, $year);
}

I've tested it with a few examples and seems to work always, be sure to double-check it though ;)

我用几个例子对它进行了测试,似乎总是有效,但一定要仔细检查一下;)

#2

The language-agnostic version:

与语言无关的版本:

To get the first particular day of the month, start with the first day of the month: yyyy-mm-01. Use whatever function is available to give a number corresponding to the day of the week. Subtract that number from the day you are looking for; for example, if the first day of the month is Wednesday (2) and you're looking for Friday (4), subtract 2 from 4, leaving 2. If the answer is negative, add 7. Finally add that to the first of the month; for my example, the first Friday would be the 3rd.

要获得该月的第一天,请从该月的第一天开始:yyyy-mm-01。使用任何可用的函数来给出与星期几相对应的数字。从你想要的那天减去那个数字;例如,如果该月的第一天是星期三(2)并且您正在寻找星期五(4),则从4减去2,留下2.如果答案是否定的,则添加7.最后将其添加到第一天这个月;就我而言,第一个星期五将是第三个星期五。

To get the last Friday of the month, find the first Friday of the next month and subtract 7 days.

要获得本月的最后一个星期五,找到下个月的第一个星期五,减去7天。

#3

strtotime() can help you. e.g.

strtotime()可以帮助你。例如

<?php
$tsFirst = strtotime('2009-04-00 next friday');
$tsLast = strtotime('2009-05-01 last friday');
echo date(DATE_RFC850, $tsFirst), " | ", date(DATE_RFC850, $tsLast);

prints

Friday, 03-Apr-09 00:00:00 CEST | Friday, 24-Apr-09 00:00:00 CEST

#4

PHP's built-in time functions make this simple.

PHP的内置时间函数使这一点变得简单。

http://php.net/manual/en/function.strtotime.php

// Get first Friday of next month.
$timestamp = strtotime('first fri of next month');

// Get second to last Friday of the current month.
$timestamp = strtotime('last fri of this month -7 days');

// Format a timestamp as a human-meaningful string.
$formattedDate = date('F j, Y', strtotime('first wed of last month'));

Note that we always want to make sure that we've defined the correct timezone for use with strtotime so that PHP has an understanding of where to compute the timestamp for relative to what time zone the machine thinks it's in.

请注意,我们总是希望确保我们已经定义了与strtotime一起使用的正确时区,以便PHP了解在何处计算相对于机器认为的时区的时间戳。

date_default_timezone_set('America/New_York');
$formattedDate = date('F j, Y', strtotime('first wed of last month +1 week'));

#5

No need for calculations or loops - this is very easy to do with strtotime():

无需计算或循环 - 使用strtotime()非常容易:

Find the the Nth or Last occurrence of a particular day of a particular a month:

查找特定月份的特定日期的第N次或最后一次出现:

/////////////////////////////////////////////////////////////////
// Quick Code
/////////////////////////////////////////////////////////////////

// Convenience mapping.
$Names = array( 0=>"Sun", 1=>"Mon", 2=>"Tue", 3=>"Wed", 4=>"Thu", 5=>"Fri", 6=>"Sat" );

// Specify what we want
// In this example, the Second Monday of Next March
$tsInMonth = strtotime('March');
$Day = 1;
$Ord = 2;

// The actual calculations
$ThisMonthTS = strtotime( date("Y-m-01", $tsInMonth ) );
$NextMonthTS = strtotime( date("Y-m-01", strtotime("next month", $tsInMonth) ) );
$DateOfInterest = (-1 == $Ord) 
    ? strtotime( "last ".$Names[$Day], $NextMonthTS ) 
    : strtotime( $Names[$Day]." + ".($Ord-1)." weeks", $ThisMonthTS ); 


/////////////////////////////////////////////////////////////////
// Explanation
/////////////////////////////////////////////////////////////////

// Specify the month of which we are interested.
// You can use any timestamp inside that month, I'm using strtotime for convenience.
$tsInMonth = strtotime('March');

// The day of interest, ie: Friday.  
// It can be 0=Sunday through 6=Saturday (Like 'w' from date()).
$Day = 5;

// The occurrence of this day in which we are interested.  
// It can be 1, 2, 3, 4 for the first, second, third, and fourth occurrence of the day in question in the month in question.
// You can also use -1 to fine the LAST occurrence.  That will return the fifth occurrence if there is one, else the 4th.
$Ord = 3;

////////////////////////////////////////////////////////////////
// We now have all the specific values we need.
// The example values above specify the 3rd friday of next march
////////////////////////////////////////////////////////////////

// We need the day name that corresponds with our day number to pass to strtotime().
// This isn't really necessary = we could just specify the string in the first place, but for date calcs, you are more likely to have the day number than the string itself, so this is convenient.
$Names = array( 0=>"Sun", 1=>"Mon", 2=>"Tue", 3=>"Wed", 4=>"Thu", 5=>"Fri", 6=>"Sat" );

// Calculate the timestamp at midnight of the first of the month in question.
// Remember $tsInMonth is any date in that month.
$ThisMonthTS = strtotime( date("Y-m-01", $tsInMonth ) );

// Calculate the timestamp at midnight of the first of the FOLLOWING month.
// This will be used if we specify -1 for last occurrence.
$NextMonthTS = strtotime( date("Y-m-01", strtotime("next month", $tsInMonth) ) );

// Now we just format the values a bit and pass them to strtotime().
// To find the 1,2,3,4th occurrence, we work from the first of the month forward.
// For the last (-1) occurence,work we work back from the first occurrence of the following month.
$DateOfInterest = (-1 == $Ord) ?
    strtotime( "last ".$Names[$Day], $NextMonthTS ) : // The last occurrence of the day in this month.  Calculated as "last dayname" from the first of next month, which will be the last one in this month. 
    strtotime( $Names[$Day]." + ".($Ord-1)." weeks", $ThisMonthTS ); // From the first of this month, move to "next dayname" which will be the first occurrence, and then move ahead a week for as many additional occurrences as you need.

#6

echo date('Y-m-d',strtotime('last friday'));

#7

You can use mktime to retrieve the unix timestamp of the first day in the month:

您可以使用mktime来检索当月第一天的unix时间戳:

$firstOfMonth = mktime(0, 0, 0, $month, 1, $year);

When you have the date of the first day of a certain month it's easy to retrieve the weekday for that date using date:

如果您拥有某个月第一天的日期,则可以使用日期轻松检索该日期的工作日:

$weekday = date("N", $firstOfMonth);

From there it's rather easy to just step forward to get the date you're after.

从那里开始,你可以很容易地前进来获得你所追求的日期。

#8

function get_date($month, $year, $week, $day) {
    # $month, $year: current month to search in
    # $week: 0=1st, 1=2nd, 2=3rd, 3=4th, -1=last
    # $day:  0=mon, 1=tue, ..., 6=sun

    $startday=1; $delta=0;
    if ($week < 0) {
        $startday = date('t', mktime(0, 0, 0, $month, 1, $year)); # 28..31
        $delta=1;
    }
    $start  = mktime(0, 0, 0, $month, $startday, $year);
    $dstart = date('w', $start)-1; # last of the month falls on 0=mon,6=sun
    $offset=$day-$dstart; if ($offset<$delta){$offset+=7;}
    $newday=$startday+$offset+($week*7);
    return mktime(0, 0, 0, $month, $newday, $year);
}

This works for me, and based on the language-agnostic version :-) Only too bad, I needed to do that delta-thing (for if the last day of the month is the wanted week-day, we do not need to subtract 7)

这对我有用,并且基于语言无关的版本:-)只是太糟糕了,我需要做三角形的事情(因为如果这个月的最后一天是想要的工作日,我们不需要减去7)

#9

Just find out what the first and last day of the month in question is (i.e. May 1, 2009 is a Friday and May 31, 2009 is a Sunday) I believe most PHP functions use Monday=0, Sunday=6, thus Friday=4, so you know that Sunday (6) - Friday (4) = 2, then 31-2 = 29, meaning the last friday of this month is on the 29th. For the first Friday, if the number is negative, add 7, if the number is 0, the month starts on Friday.

只是找出当月的第一天和最后一天是什么(即2009年5月1日是星期五和2009年5月31日星期日)我相信大多数PHP函数使用星期一= 0,星期日= 6,因此星期五= 4,所以你知道星期日(6) - 星期五(4)= 2,然后31-2 = 29,这意味着本月的最后一个星期五是29日。对于第一个星期五,如果数字为负数,则添加7,如果数字为0,则月份从星期五开始。

#10

The same can be accomplished very elegantly using the DateTime class.

使用DateTime类可以非常优雅地完成相同的操作。

$time_zone = new DateTimeZone('Europe/Ljubljana');

$first_friday_of_this_month = new DateTime('first Friday of this month', $time_zone);
$last_friday_of_this_month = new DateTime('last Friday of this month', $time_zone);

echo $first_friday_of_this_month->format('Y-m-d');  # 2015-11-06
echo $last_friday_of_this_month->format('Y-m-d');  # 2015-11-27

#11

This seems to work perfect everytime; it takes any date provided and returns the date of the last friday of the month, even in case of 5 friday in the month.

这似乎每次都很完美;它需要提供任何日期并返回该月的最后一个星期五的日期,即使是在该月的5个星期五。

function get_last_friday_of_month($inDate) {
    $inDate = date('Y-m-24', strtotime($inDate));
    $last_friday = date('Y-m-d',strtotime($inDate.' next friday'));
    $next_friday = date('Y-m-d',strtotime($inDate.' next friday'));

    if(date('m', strtotime($last_friday)) === date('m', strtotime($next_friday))){
        $last_friday = $next_friday;
    }else{
        //
    }
    return $last_friday;
}

#12

Below is the quickest solution and you can use in all conditions. Also you could get an array of all day of week if you tweak it a bit.

以下是最快的解决方案,您可以在所有条件下使用。如果你稍微调整一下,你也可以获得一周中所有星期的数组。

function findDate($date, $week, $weekday){
    # $date is the date we are using to get the month and year which should be a datetime object
    # $week can be: 0 for first, 1 for second, 2 for third, 3 for fourth and -1 for last
    # $weekday can be: 1 for Monday, 2 for Tuesday, 3 for Wednesday, 4 for Thursday, 5 for Friday, 6 for Saturday and 7 for Sunday 

    $start = clone $date;
    $finish = clone $date;

    $start->modify('first day of this month');
    $finish->modify('last day of this month');
    $finish->modify('+1 day');

    $interval = DateInterval::createFromDateString('1 day');
    $period = new DatePeriod($start, $interval, $finish);

    foreach($period AS $date){
        $result[$date->format('N')][] = $date;
    }

    if($week == -1)
        return end($result[$weekday]);
    else
        return $result[$weekday][$week];
}


$date = DateTime::createFromFormat('d/m/Y', '25/12/2016');

# find the third Wednesday in December 2016
$result = findDate($date, 2, 3); 
echo $result->format('d/m/Y');

I hope this helps.

我希望这有帮助。

Let me know if you need any further info.

如果您需要任何进一步的信息,请告诉我。