Finding First Day of Week via PHP

Get first/last day of week in php?

Something like this:

<?php
date_default_timezone_set("Asia/Kolkata");
$today = date("Y-m-d");
$mon = new DateTime($today);
$sun = new DateTime($today);
$mon->modify('last Monday');
$sun->modify('next Sunday');
var_dump($mon);
var_dump($sun);
$first_day_of_week = $mon->format("Y-m-d");
$last_day_of_week = $sun->format("Y-m-d");

Get first day date of the week on a given date PHP

You can do the following:

 $dateTime = new DateTime("2015-12-16");

 $weekNo = $dateTime->format("W");

 $newDate = new DateTime();
 $newDate->setISODate($dateTime->format("Y"), $weekNo);

Example:

http://sandbox.onlinephpfunctions.com/code/281a1ac298bfee8be421e333e4b7e92c6bb44d65

Since the above is a bit off in some cases here's something more reliable:

 $dateTime = new DateTime("2016-01-01");
 $dateTime->sub(new DateInterval("P".($dateTime->format("w")-1)."D"));  //Since the weekdays are 1-based.

Example:
http://sandbox.onlinephpfunctions.com/code/c5cb0f077fa77974d977ddbffa6bc0b61f9d7851

PHP - get first day of a given week number when week starts on day other than Monday

Use DateTime::setISODate, where 3rd parameter is day of the week:

$dt = new DateTime;
echo $dt->setISODate(2014, 1, 0)->format('Y-m-d'), "\n"; # 0 = Sunday
echo $dt->setISODate(2014, 1, 1)->format('Y-m-d'), "\n"; # 1 = Monday
echo $dt->setISODate(2014, 1, 6)->format('Y-m-d'), "\n"; # 6 = Saturday

demo demo #2

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Your example isn't working, because you are using format yyyyWweek, which is by default Monday. Read about ISO-8601 formats, and you will see that there is format yyyy-Wweek-day, which you can use like:

$format = sprintf("%d-W%02d-%d", $year, $weeknumber, $weekstarts == 7 ? 0 : $weekstarts);
$first_day_of_week = strtotime($format);
echo "$format returned $first_day_of_week\n";

demo

PHP Find the first day-of-week in a given time period

Just a little math with the date('N') (day of the week) value:

$timestamp = strtotime('2011-11-08');
$weekday   = date('N', $timestamp);

if ($weekday > 1) {
    $timestamp = strtotime('+' . abs(8 - $weekday) . ' days', $timestamp);
}

echo date('D Y-m-d', $timestamp);

How to set the first day of the week to Thursday in PHP

http://php.net/manual/en/datetime.formats.relative.php says that as of PHP version 5.6.23, 7.0.8 "Weeks always start on monday. Formerly, sunday would also be considered to start a week." That said, is your problem that the number of weeks returned might be incorrect depending on whether today falls on or before Thursday of the current week? Maybe try something like this:

$date = new DateTime();
$week = intval($date->format('W'));
$day = intval($date->format('N'));
echo $day < 4 ? $week-1 : $week;

If subtracting 1 isn't the answer you could play around with addition/subtraction, comparing the result with the actual answer you know to be true until you get the right formula. Hope this helps!

How to get the first day of a given week number in PHP (multi-platform)?

Yet another solution:

<?php
        $week = 3;
        $year = 2009;

        $timestamp = mktime( 0, 0, 0, 1, 1,  $year ) + ( $week * 7 * 24 * 60 * 60 );
        $timestamp_for_monday = $timestamp - 86400 * ( date( 'N', $timestamp ) - 1 );
        $date_for_monday = date( 'Y-m-d', $timestamp_for_monday );
?>

Finding First day of week via php

strtotime is quite powerful with relative time formats:

strtotime('monday this week');
strtotime('sunday this week');
strtotime('monday last week');
strtotime('sunday last week');

(this only works with PHP 5.3+)

strtotime('first day of this month');
strtotime('last day of this month');
strtotime('first day of last month');
strtotime('last day of last month');

In order to get the first and last date of a month in PHP < 5.3, you can use a combination of mktime and date (date('t') gives the number of days of the month):

mktime(0,0,0,null, 1); // gives first day of current month
mktime(0,0,0,null, date('t')); // gives last day of current month

$lastMonth = strtotime('last month');
mktime(0,0,0,date('n', $lastMonth), 1); // gives first day of last month
mktime(0,0,0,date('n', $lastMonth), date('t', $lastMonth); // gives last day of last month

If you just want to get a string for presentation, then you don't need mktime:

date('Y-m-1'); // first day current month
date('Y-m-t'); // last day current month
date('Y-m-1', strtotime('last month')); // first day last month
date('Y-m-t', strtotime('last month')); // last day last month

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