date value in php

$today = date("F j, Y, g:i a");               // March 10, 2001, 5:16 pm
$today = date("m.d.y");                       // 03.10.01
$today = date("j, n, Y");                     // 10, 3, 2001
$today = date("Ymd");                         // 20010310
$today = date('h-i-s, j-m-y, it is w Day');   // 05-16-18, 10-03-01, 1631 1618 6 Satpm01
$today = date('\i\t \i\s \t\h\e jS \d\a\y.'); // it is the 10th day.
$today = date("D M j G:i:s T Y");             // Sat Mar 10 17:16:18 MST 2001
$today = date('H:m:s \m \i\s\ \m\o\n\t\h');   // 17:03:18 m is month
$today = date("H:i:s");                       // 17:16:18
$today = date("Y-m-d H:i:s");                 // 2001-03-10 17:16:18 (the MySQL DATETIME format)
// get day of month php
// Method 1; some server not work, I had check php 7.3.24 not worked, php 7.3.8 worked
cal_days_in_month(CAL_GREGORIAN, $month, $year)
echo (cal_days_in_month(CAL_GREGORIAN, 2, 2020)); // => 29

// Method 2;
function days_in_month($month, $year) {
    // calculate number of days in a month
    return $month == 2 ? ($year % 4 ? 28 : ($year % 100 ? 29 : ($year % 400 ? 28 : 29))) : (($month - 1) % 7 % 2 ? 30 : 31);
}

// Method 3;
echo (date('t', strtotime('2020-02-1')));	// 29