php complete date code example

Example 1: date 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 (10ème jour du mois).
$today = date("D M j G:i:s T Y");                 // Sat Mar 10 17:16:18 MST 2001
$today = date('H:m:s \m \e\s\t\ \l\e\ \m\o\i\s'); // 17:03:18 m est le mois
$today = date("H:i:s");                           // 17:16:18
$today = date("Y-m-d H:i:s");                     // 2001-03-10 17:16:18 (le format DATETIME de MySQL)

Example 2: php format date

<?php
  // To change the format of an existing date
  $old_date_format = "20/03/1999";
  $new_data_format = date("Y-m-d H:i:s", strtotime($old_date_format));

Example 3: php week of a date

Things to be aware of when using week numbers with years.

<?php
echo date("YW", strtotime("2011-01-07")); // gives 201101
echo date("YW", strtotime("2011-12-31")); // gives 201152
echo date("YW", strtotime("2011-01-01")); // gives 201152 too
?>

BUT

<?php
echo date("oW", strtotime("2011-01-07")); // gives 201101
echo date("oW", strtotime("2011-12-31")); // gives 201152
echo date("oW", strtotime("2011-01-01")); // gives 201052 (Year is different than previous example)
?>

Reason:
Y is year from the date
o is ISO-8601 year number
W is ISO-8601 week number of year

Conclusion:
if using 'W' for the week number use 'o' for the year.