PHP Mktime shows 2 March’s when I dump foreach month

I’ve been using the following function fine until the other day when the clocks went forward:

function months($month_format="F") {
$array = array();
for ($i = 1; $i <=12; $i++) {
    $array[$i]['string'] = date($month_format, mktime(0,0,0,$i));
    $array[$i]['int'] = date('m', mktime(0,0,0,$i));
}
return $array;
}

It outputs an array with:

• string[]
• int[]

Since the other day (like 2 days ago, when the clocks went forward in the UK), the function seems to be showing me 2 march months and 0 Februarys….

Very very strange… I’m using rethinkdb with their eachPosTime function… not sure if this is causing it.

I tried using a different function, but still using mktime:

function months(){
 $start_month = 1;
 $end_month = 12;
 $start_year = date("Y");
 $array = array();
 for($m=$start_month; $m<=12; ++$m){

    echo $m.'<br>';

    $array[$m]['string'] = date('F', mktime(0,0,0,$m));
    $array[$m]['int'] = date('m', mktime(0,0,0,$m));

       if($start_month == 12 && $m==12 && $end_month < 12) 
       {
           $m = 0;
           $start_year = $start_year+1;
       }
 //echo date('F Y', mktime(0, 0, 0, $m, 1, $start_year)).'<br>';
 if($m == $end_month) break;
}
return $array;
}

Still, I am having no luck. Check the image here, which shows the output of the months() function:

Output of the months() function

Answer

This is not to do with the clocks changing, but the time of the month, and the entirely unhelpful signature of the mktime function.

When you leave out parameters from a “mktime” call, they are filled in with today’s date. In your case, you specified month without day or year, so when you ask for mktime(0, 0, 0, 2); it will fill in today’s day and year, and look for the 29th February 2021 – a day that doesn’t exist. Since the time library “overflows” dates, this becomes the 1st March.

The solution is to pass an explicit day to “mktime”, as in mktime(0,0,0,$m,1) or to use a less confusing function.