php get day number

1$timestamp = strtotime('2009-10-22');
2
3$day = date('D', $timestamp);
4var_dump($day);

1// Prints the day
2echo date("l") . "<br>";

1$datetime = DateTime::createFromFormat('YmdHi', '201308131830');
2echo $datetime->format('D');
3
4// or 
5
6$date = new \DateTime();
7echo $date->format("D");
8
9

1// get day of month php
2// Method 1; some server not work, I had check php 7.3.24 not worked, php 7.3.8 worked
3cal_days_in_month(CAL_GREGORIAN, $month, $year)
4echo (cal_days_in_month(CAL_GREGORIAN, 2, 2020)); // => 29
5
6// Method 2;
7function days_in_month($month, $year) {
8    // calculate number of days in a month
9    return $month == 2 ? ($year % 4 ? 28 : ($year % 100 ? 29 : ($year % 400 ? 28 : 29))) : (($month - 1) % 7 % 2 ? 30 : 31);
10}
11
12// Method 3;
13echo (date('t', strtotime('2020-02-1')));	// 29
14
15
16

1$today = date("d");
2//Can Convert TO Int
3print_r($today);