The Posix-module has a very nice function called strftime() that is capable of formatting dates and times to a human readable format.

But ... the manpage is not very descriptive. It tells you nothing about the meanings of the parameters in the format string.

Unix/Linux users can read about them by typing

$ date --help
[download]

(thanks blokhead for advising me on that), but Windows users are lost.

Therefore, in the hope it will help somebody*, i post this little script, that can serve both as a reference and as an example.

use strict;
use POSIX qw(strftime);

print strftime qq{
a: Day of Week    (short, text) %a
A: Day of Week     (long, text) %A
b: Monthname      (short, text) %b
B: Monthname       (long, text) %B
c: Full datetime (number, long) %c
d: Day                 (number) %d
H: Hour (24 hour)      (number) %H
I: Hour (12 hour)      (number) %I
j: Day of year         (number) %j
m: Month               (number) %m
M: Minutes             (number) %M
p: am/pm/empty           (text) %p 
S: Seconds             (number) %S
U: Week of Year        (number) %U
w: Day of week         (number) %w
W: Week of Year        (number) %W
x: date                (number) %x
X: time                (number) %X
y: year         (short, number) %y
Y: year          (long, number) %Y
Z: timezone              (text) %Z
},
localtime;
[download]

Notes:
The parameters %U and %W, are not identical. %U starts counting the Week Of Year at sundays, %W starts counting on mondays.
The %p parameter can be empty, depending on the locale of the system.

*and for my own convenience

Update: corrected typo for %M
Update: corrected typo for %I (thanks bmann)
Update: retitled node from "strftime reference" to "strftime reference for win32"