It seems that you can't use strotime if you need reliable and accurate date manipulation. For example, if the month has 31 days, then it appears that strtotime simply minuses 30 days, not a whole month.
So, for example, if $event["EndDate"] is equal to "2013-10-31 00:00:01", the following code:
echo date("Y/n/j", strtotime('-1 month', strtotime($event["EndDate"]));
Ouputs: 2013/10/1 instead of 2013/09/30.
QUESTION: Now how I know how NOT to do it, is there another, more accurate, way to make PHP subtract (or add) exactly a whole month, and not just 30 days?
The main issue is that 2013/09/31 does not exist so a better approach would be to use first day or last day of the previous month.
$date = new DateTime("2013-10-31 00:00:01");
$date->modify("last day last month");
echo $date->format("Y/n/j"); // 2013/9/30
When date is 2013-10-15
$date = new DateTime("2013-10-15 00:00:01");
$day = $date->format("d");
$year = $date->format("Y");
$date->modify("last day last month");
$month = $date->format("m");
if (checkdate($month, $day, $year)) {
$date->setDate($year, $month, $day);
}
echo $date->format("Y/n/j"); // 2013-9-15
You say:-
It seems that you can't use strotime if you need reliable and accurate date manipulation
You can, you just need to know how it behaves. Your question prompted me to run a couple of tests.
PHP does not merely subtract 30 days from the date when subtracting a month, although it appears that it does from the single case you are looking at. In fact my test here suggests that it adds 31 days to the start of the previous month (the result of 3rd March suggests this to me) in this case.
$thirtyOnedayMonths = array(
1, 3, 5, 7, 8, 10, 12
);
$oneMonth = new \DateInterval('P1M');
$format = 'Y-m-d';
foreach($thirtyOnedayMonths as $month){
$date = new \DateTime("2013-{$month}-31 00:00:01");
var_dump($date->format($format));
$date->sub($oneMonth);
var_dump($date->format($format));
}
There are 31 days between 2013-11-12 and 2013-10-12 and PHP calculates the month subtraction correctly as can be seen here.
$date = new \DateTime('2013-11-12 00:00:01');
var_dump($date);
$interval = new DateInterval('P1M');
$date->sub($interval);
var_dump($date);
In your particular case 2013-10-31 - 1 month is 2013-09-31 which does not exist. Any date/time function needs to return a valid date, which 2013-09-31 is not.
In this case PHP, as I stated above, seems to add 31 days to the start of the previous month to arrive at a valid date.
Once you know the expected behaviour, you can program accordingly. If the current behaviour does not fit your use case then you could extend the DateTime class to provide behaviour that works for you.
I have assumed that strtotime and DateTime::sub() behave the same, this test suggests they do.
$thirtyOnedayMonths = array(
1, 3, 5, 7, 8, 10, 12
);
$format = 'Y-m-d';
foreach($thirtyOnedayMonths as $month){
$date = date($format, strtotime('-1 month', strtotime("2013-{$month}-31 00:00:01")));
var_dump($date);
}
How can I get last year's start and end date using PHP code? Is it possible?
The first day is always January 1, the last day is always December 31. You're really only changing the year attached to it. Depending on how you want the date formatted, you have a couple possibilities...
If you just want to display the physical date:
$year = date('Y') - 1; // Get current year and subtract 1
$start = "January 1st, {$year}";
$end = "December 31st, {$year}";
If you need the timestamp for both those dates:
$year = date('Y') - 1; // Get current year and subtract 1
$start = mktime(0, 0, 0, 1, 1, $year);
$end = mktime(0, 0, 0, 12, 31, $year);
Very simple stuff. You can manually specify which year if you wanted too. The premise is the same.
You can do it by using the below. Hope it helps someone.
//to get start date of previous year
echo date("d-m-y",strtotime("last year January 1st"));
//to get end date of previous year
echo date("d-m-y",strtotime("last year December 31st"));
start date of the year :
mktime(0,0,0,1,1,$year);
end date of the year :
mktime(0,0,0,1,0,$year+1);
Check this Stuff
$currentY = date('Y');
$lastyearS = mktime(0, 0, 0, 1, 1, $currentY-1 )."<br/>";
$lastyearE = mktime(0, 0, 0, 12, 31, $currentY-1 )."<br/>";
echo date('Y-m-d',$lastyearS)."<br/>";echo date('Y-m-d',$lastyearE);
Suppose if your current month is February or the month which has 30 days
echo date('Y-12-t', strtotime(date('Y-m-d'))); // if current month is february (2015-02-01) than it gives 2015-02-28
will give you inaccurate results
Solution:
So to get accurate result for the end date of an year, try the code below
$start_date = date("Y-01-01", strtotime("-1 year"));// get start date from here
$end_date = date("Y-12-t", strtotime($start_date));
(OR)
$last_year_last_month_date = date("Y-12-01", strtotime("-1 year"));
$end_date = date("Y-12-t", strtotime($last_year_last_month_date));
I'm trying to get the number of month before of the current month (now is 04 (april), so I'm trying to get 03). I'm trying this:
date('m')-1;
but I get 3. But what I want is to get 03.
The correct way to do this really is:
date('m', strtotime('-1 month'));
As you will see strange things happen in January with other answers.
The currently accepted response will result in an incorrect answer whenever the day of the month (for the current day) is a larger number than the last day of the month for the previous month.
e.g. The result of executing date('m', strtotime('-1 month')); on March 29th (in a non-leap-year) will be 03, because 29 is larger than any day of the month for February, and thus strtotime('-1 month') will actually return March 1st.
Instead, use the following:
date('n') - 1;
You may be surprised, but date() function manual page has an exact example of what you need:
$lastmonth = mktime(0, 0, 0, date("m")-1, date("d"), date("Y"));
The result of your calculation is a number. If you want to format it like a string, you can use:
$result = date('m')-1;
$string_result = sprintf("%02s", $result);
Edit: Note that this is only a partial solution to format a number like a string.
intval(date('m'))
for the current month
(intval(date('m'))-1)%12
for the previous month, also for december/january
date('m', strtotime('last month'));
This will work regardless of whether or not you're in January
This works too.
printf("%02s", (date('m') - 1));
This should do it for you...
str_pad(date('m')-1, 2, '0', STR_PAD_LEFT);
I'm trying to write a calendar function like this
function get_date($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.
For an example, let's call
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
get_date(5, 2009, 2, 'Sun', 'backward');
, it returns the second last Sunday in May ie 2009-05-24.
The language-agnostic version:
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.
To get the last Friday of the month, find the first Friday of the next month and subtract 7 days.
Perhaps it can be made quicker...
This was VERY interesting to code.
Please note that $direction is 1 for forward and -1 for backward to ease things up :)
Also, $day begins with a value of 1 for Monday and ends at 7 for Sunday.
function get_date($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 ;)
PHP's built-in time functions make this simple.
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.
date_default_timezone_set('America/New_York');
$formattedDate = date('F j, Y', strtotime('first wed of last month +1 week'));
strtotime() can help you. e.g. <?php
$tsFirst = strtotime('2009-04-00 next friday');
$tsLast = strtotime('2009-05-01 last friday');
echo date(DATE_RFC850, $tsFirst), " | ", date(DATE_RFC850, $tsLast);printsFriday, 03-Apr-09 00:00:00 CEST | Friday, 24-Apr-09 00:00:00 CEST
No need for calculations or loops - this is very easy to do with strtotime():
Find the the Nth or Last occurrence of a particular day of a particular a month:
/////////////////////////////////////////////////////////////////
// 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.
echo date('Y-m-d',strtotime('last friday'));
You can use mktime to retrieve the unix timestamp of the first day in the month:
$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:
$weekday = date("N", $firstOfMonth);
From there it's rather easy to just step forward to get the date you're after.
function get_date($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)
The same can be accomplished very elegantly using the DateTime class.
$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 $last_friday_of_this_month->format('Y-m-d'); # 2015-11-27
Just find out what the first and last day of the month in question is (i.e. May 1, 2009 is a Friday and May 31, 2009 is a Sunday) I believe most PHP functions use Monday=0, Sunday=6, thus Friday=4, so you know that Sunday (6) - Friday (4) = 2, then 31-2 = 29, meaning the last friday of this month is on the 29th. For the first Friday, if the number is negative, add 7, if the number is 0, the month starts on Friday.
This seems to work perfect everytime; it takes any date provided and returns the date of the last friday of the month, even in case of 5 friday in the month.
function get_last_friday_of_month($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 $last_friday;
}
Below is the quickest solution and you can use in all conditions. Also you could get an array of all day of week if you tweak it a bit.
function findDate($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.
Let me know if you need any further info. ;)