How to get year-sensitive calendar week ? date(“W”) gives back 52 for 1st of January

Question

As the headline says, PHP\'s date(\"W\") function gives back the calendar week (for the current day). Unfortunatly it gives back 52 or 53 for the first day(s) of most years.

Answer 1

This solution converts the excess of december to week 53 and everything in january prior to week 1 to week 0.

$w=(int)date('W');
$m=(int)date('n');
$w=$w==1?($m==12?53:1):($w>=51?($m==1?0:$w):$w);

echo "week $w in ".date('Y');

2013-12-31 ==> week 53 in 2013

2014-01-01 ==> week 1 in 2014

2015-12-31 ==> week 52 in 2015

2016-01-01 ==> week 0 in 2016

And a small test run, so you can see for yourself ;-)

$id=array(25,26,27,28,29,30,31,1,2,3,4,5,6,7,8);        
for($iy=2013;$iy<2067;++$iy){foreach($id as $k=>$v){if($k<7){$im=12;}else{$im=1;}
if($k==7){++$iy;echo '====
';}$tme=strtotime("$im/$v/$iy");
echo date('d-m-Y',$tme),'  * *  ';
//THE ACTUAL CODE =================
    $w=(int)date('W',$tme);
    $m=(int)date('n',$tme);
    $w=$w==1?($m==12?53:1):($w>=51?($m==1?0:$w):$w);
//THE ACTUAL CODE =================
echo 'WEEK: ',$w,' --- ','YEAR: ',date('Y',$tme),'
';}--$iy;
echo '----------------------------------
';}