Description:
------------
I'm a french developer computer.
For an internet tool I need to get a list of weeks after having selected one year and one month.
By testing I found a BUG in the year 2016.
PHP gives me:
1 January 2016 the number of week: 53 (instead of 1)
January 31, 2016 the number of week: 4 (instead of 5)
then the error shifts in other months.
The system works correctly in 2013, 2014, 2015.

I provide you sample of the code that allows me to build this list of weeks, I particularly use mktime ()

// timestamp of first day of month
$time = mktime(0,0,0,$mois_select,1,$annee_select);
// number of days of month
$nbrJoursMois = intval(date('t',$time));
// the number of the first week
$numSemaineDebutMois = intval(date('W', $time));
// timestamp of end month
$timeFinMois = mktime(0,0,0,$mois_select,$nbrJoursMois,$annee_select);
// the number of the last week
$numSemaineFinMois = intval(date('W', $timeFinMois));

/**** Display results ****/
$annee_select = 2016
$mois_select = 1
$time = 1451602800
$nbrJoursMois = 31
$numSemaineDebutMois = 53  (Error)
$timeFinMois = 1454194800
$numSemaineFinMoisnum = 4   (Error)