php 查找 2010 年第 16 周的开始

Question

Ok so I want to get the Monday of week 16 in 2010 (more precisely to week $week of year $year). here is what I have in my test.php file

$week = 16;
$year = 2010;
$dateString = $dateString = 'Start of week ' . $week . ' in ' . $year;
$date = strtotime( $dateString );
echo $date;

The value returned is false. I have also tried using Monday of week... but this also gave a false result.

any idea how to get a date given a week number and the year?

thanks

Answer 1

I'd recommend using the builtin \DateTime class.

Inspired by the answer here I tested the following code:

<?php

function getStartDate($week, $year) {
    $dto = new DateTime();
    $dto->setISODate($year, $week);
    return $dto->format('Y-m-d');
}

$week = 16;
$year = 2010;

var_dump(getStartDate($week, $year));

This returned the following:

/some/fancy/path/test.php:12:string '2010-04-19' (length=10)

Answer 2

Monday is the first day of the week. Make use of setISODate()

<?php

$gendate = new DateTime();
$gendate->setISODate(2022,2,1); //year , week num , day
echo $gendate->format('d-m-Y'); //"prints"  10-01-2022