Check Working Day

Thanks to all people that post it's code I've made two useful functions to check working days on each month, and render week times in a combo.

function working_days (){
$date = date('Y-m-d');
$year = substr($date, 0,4);
$month = substr($date, 5, 2);
$day = substr($date, 8, 2);

$d_daysinmonth = date('t', mktime(0,0,0,$month,1,$year)); // how many days in month
$full_weeks = ceil ($d_daysinmonth / 7);
$festive_days = floor(($d_daysinmonth / 7) * 2);
$total_working_days = $d_daysinmonth - $festive_days;
$total_working_hours = $total_working_days * 8;
return $total_working_days;
}

function working_weeks_combo () {

$date = date('Y-m-d');
$year = substr($date, 0,4);
$month = substr($date, 5, 2);
$day = substr($date, 8, 2);

$d_daysinmonth = date('t', mktime(0,0,0,$month,1,$year)); // how many days in month
$full_weeks = ceil ($d_daysinmonth / 7);
$d_firstdow = date('w', mktime(0,0,0,$month,'1',$year)); // FIRST falls on what day of week (0-6)
$ajuste = $d_firstdow -1;
$new_date = date('Y-m-d', strtotime("$year-$month-01 - $ajuste days"));
echo '<select name="working_week">';
for ($ax=0; $ax < $full_weeks; $ax++){
echo "<option>".date('Y-m-d', strtotime($new_date. "+ $ax week"));
}
echo "</select>";
}