php date time formatting

<?php
$date = DateTime::createFromFormat('j-M-Y', '15-Feb-2009');
echo $date->format('Y-m-d');
?>

a - "am" or "pm"
A - "AM" or "PM"
d - day of the month, 2 digits with leading zeros; "01" to "31"
D - day of the week as text, 3 letters; "Mon"
F - month as text, full name; "January"
h - hour, 12-hour format; "01" to "12"
H - hour, 24-hour format; "00" to "23"
g - hour, 12-hour format without leading zeros; "1" to "12"
G - hour, 24-hour format without leading zeros; "0" to "23"
i - minutes; "00" to "59"
j - day of the month as a number without leading zeros; "1" to "31"
l (lowercase L) - day of the week as text, full name; "Monday"
L - boolean for if it is a leap year; "0" or "1"
m - month as a number; "01" to "12"
n - month as a number without leading zeros; "1" to "12"
M - month as text, 3 letters; "Jan"
s - seconds; "00" to "59"
S - English ordinal suffix as text, 2 characters; "th", "nd"
t - number of days in the given month; "28" to "31"
U - seconds since the epoch
w - day of the week as a number; "0" (Sunday) to "6" (Saturday)
Y - year, 4 digits; "1999"
y - year, 2 digits; "99"
z - day of the year; "0" to "365"
Z - timezone offset in seconds ("-43200" to "43200")