<?php
// function to get time
// for another time zone
// given a specific timestamp and hour offset from GMT

function getLocalTime($ts, $offset) {
// performs conversion
// returns UNIX timestamp
return ($ts - date("Z", $ts)) + (3600 * $offset);
}
// get current local time in Singapore
// result: "00:11:26 31-10-06 SST"
echo date("H:i:s d-m-y", getLocalTime(mktime(), 8)) . " SST \n";
// get current local time in India
// result: "21:41:26 30-10-06 IST"
echo date("H:i:s d-m-y", getLocalTime(mktime(), +5.5)) . " IST \n";
// get current local time in USA (Eastern)
// result: "11:11:26 30-10-06 EST"
echo date("H:i:s d-m-y", getLocalTime(mktime(), -5)) . " EST \n";
// get current local time in USA (Pacific)
// result: "08:11:26 30-10-06 PST"
echo date("H:i:s d-m-y", getLocalTime(mktime(), -8)) . " PST \n";
// get time in GMT
// when it is 04:30 AM in India
// result: "23:00:00 01-02-05 GMT "
echo date("H:i:s d-m-y", getLocalTime(mktime(4,30,0,2,2,2005), 0)) .?
" GMT \n";
?>

Phút qua giờ:

<?php
// define number of minutes
$mm = 156;
// convert to hh:mm format
// result: "02h 36m"
echo sprintf("%02dh %02dm", floor($mm/60), $mm%60);
?>

Ngược lại:

<?php
// define hours and minutes
$hhmm = "02:36";
// convert to minutes
// result: "156 minutes"
$arr = explode(":", $hhmm);
echo $arr[0]*60 + $arr[1] . " minutes";
?>

<?php
// create timestamps for two dates
$date1 = mktime(0,0,0,2,1,2007);
$date2 = mktime(1,0,0,2,1,2007);
// compare timestamps
// to see which represents an earlier date
if ($date1 > $date2) {
$str = date ("d-M-Y H:i:s", $date2) . " comes before " .?
date ("d-M-Y H:i:s", $date1);
} else if ($date2 > $date1) {
$str = date ("d-M-Y H:i:s", $date1) . " comes before " .?
date ("d-M-Y H:i:s", $date2);
} else {
$str = "Dates are equal";
}
// result: "01-Feb-2007 00:00:00 comes before 01-Feb-2007 01:00:00"
echo $str;
?>

<?php
function canchi($nam)
{
$acan = array("Giap", "At", "Binh", "Dinh", "Mau", "Ky", "Canh", "Tan", "Nham", "Quy");
$achi = array("Ty", "Suu", "Dan", "Meo", "Thin", "Ty", "Ngo", "Mao", "Than", "Dau", "Tuat", "Hoi");
$can = $acan[($nam+6)%10];
$chi = $achi[($nam+8)%12];
return $can." ".$chi;
}
echo canchi(1988);
?>

Còn đây là C:

#include <stdio.h>
#include <conio.h>
void main()
{
unsigned nam;
char can[][5] = {"Giap", "At", "Binh", "Dinh", "Mau", "Ky",
"Canh", "Tan", "Nham", "Quy"};
char chi[][5] = {"Ty", "Suu", "Dan", "Meo", "Thin", "Ty",
"Ngo", "Mao", "Than", "Dau", "Tuat", "Hoi"};

printf("\nNhap nam can biet : ");
scanf("%d", &amp;amp;nam);
printf("Nam am lich cua %d la %s %s\n\n", nam, can[(nam+6)%10], chi[(nam+8)%12]);
getch();
}

//FUNCTION FOR TIME LEFT
function time_left($integer)
{

$seconds=$integer;

if ($seconds/60 >=1)

{

$minutes=floor($seconds/60);

if ($minutes/60 >= 1)

{ # Hours

$hours=floor($minutes/60);

if ($hours/24 >= 1)

{ #days

$days=floor($hours/24);

if ($days/7 >=1)

{ #weeks

$weeks=floor($days/7);

if ($weeks>=2) $return="$weeks Weeks";

else $return="$weeks Week";

} #end of weeks

$days=$days-(floor($days/7))*7;

if ($weeks>=1 && $days >=1) $return="$return, ";

if ($days >=2) $return="$return $days days";

if ($days ==1) $return="$return $days day";

} #end of days

$hours=$hours-(floor($hours/24))*24;

if ($days>=1 && $hours >=1) $return="$return, ";

if ($hours >=2) $return="$return $hours hours";

if ($hours ==1) $return="$return $hours hour";

} #end of Hours

$minutes=$minutes-(floor($minutes/60))*60;

if ($hours>=1 && $minutes >=1) $return="$return, ";

if ($minutes >=2) $return="$return $minutes minutes";

if ($minutes ==1) $return="$return $minutes minute";

} #end of minutes

$seconds=$integer-(floor($integer/60))*60;

if ($minutes>=1 && $seconds >=1) $return="$return, ";

if ($seconds >=2) $return="$return $seconds seconds";

if ($seconds ==1) $return="$return $seconds second";

$return="$return.";

return $return;

}

/* Returns a string of the amount of time the integer (in seconds) refers
to.

$timeleft=time_left(86400);

$timeleft='1 day'.

Will not return anything higher than weeks. False if $integer=0 or fails.

*/

$lettertomorse=array(
"a" => ".-",
"b" => "-...",
"c" => "-.-.",
"d" => "-..",
"e" => ".",
"f" => "..-.",
"g" => "--.",
"h" => "....",
"i" => "..",
"j" => ".---",
"k" => ".-.",
"l" => ".-..",
"m" => "--",
"n" => "-.",
"o" => "---",
"p" => ".--.",
"q" => "--.-",
"r" => ".-.",
"s" => "...",
"t" => "-",
"u" => "..-",
"v" => "...-",
"w" => ".--",
"x" => "-..-",
"y" => "-.--",
"z" => "--..",
"1" => ".----",
"2" => "..---",
"3" => "...--",
"4" => "....-",
"5" => ".....",
"6" => "-....",
"7" => "--...",
"8" => "---..",
"9" => "----.",
"0" => "-----",
" " => "   ",
"." => ".-.-.-",
"," => "--..--",
"EOM" => ".-.-."
);

$morsetoletter=array();
reset($lettertomorse);
foreach($lettertomorse as $letter => $code)
{
$morsetoletter[$code]=$letter;
}

function morse_encode($txt)
{
global $lettertomorse;

$line="";
for ($i=0;$i<strlen($txt);$i++)
{
$letter=substr($txt,$i,1);

// ignore unknown characters
if (empty($lettertomorse[$letter]))
continue;

$line.=$lettertomorse[$letter]." ";
}
return $line;
}

function morse_decode($string)
{
global $morsetoletter;

$line="";
$letters=array();
$letters=explode(" ",$string);
foreach ($letters as $letter)
{
// ignore unknown characters
if (empty($letter))
$line.=" ";
if (empty($morsetoletter[$letter]))
continue;

$line.=$morsetoletter[$letter];
}
return $line;
}

Chắc mọi người đều biết về số la mã: I, II, III, IV, V, VI, VII, VIII, IX, X….
Và…

 M = 1,000
 C = 100
 X = 10
 I = 1
 D = 500
 L = 50
 V = 5

Đây là hàm chuyển số thành số La Mã:

// A function to return the Roman Numeral, given an integer
function numberToRoman($num)
{
// Make sure that we only use the integer portion of the value
$n = intval($num);
$result = '';

// Declare a lookup array that we will use to traverse the number:
$lookup = array('M' => 1000, 'CM' => 900, 'D' => 500, 'CD' => 400,
'C' => 100, 'XC' => 90, 'L' => 50, 'XL' => 40,
'X' => 10, 'IX' => 9, 'V' => 5, 'IV' => 4, 'I' => 1);

foreach ($lookup as $roman => $value)
{
// Determine the number of matches
$matches = intval($n / $value);

// Store that many characters
$result .= str_repeat($roman, $matches);

// Substract that from the number
$n = $n % $value;
}

// The Roman numeral should be built, return it
return $result;
}

Phút sang giờ:

<?php
// define number of minutes
$mm = 156;
// convert to hh:mm format
// result: "02h 36m"
echo sprintf("%02dh %02dm", floor($mm/60), $mm%60);
?>

Và phút sang giờ:

<?php
// define hours and minutes
$hhmm = "02:36";
// convert to minutes
// result: "156 minutes"
$arr = explode(":", $hhmm);
echo $arr[0]*60 + $arr[1] . " minutes";
?>

<?php
// create timestamps for two dates
$date1 = mktime(0,0,0,2,1,2007);
$date2 = mktime(1,0,0,2,1,2007);
// compare timestamps
// to see which represents an earlier date
if ($date1 > $date2) {
$str = date ("d-M-Y H:i:s", $date2) . " comes before " .?
date ("d-M-Y H:i:s", $date1);
} else if ($date2 > $date1) {
$str = date ("d-M-Y H:i:s", $date1) . " comes before " .?
date ("d-M-Y H:i:s", $date2);
} else {
$str = "Dates are equal";
}
// result: "01-Feb-2007 00:00:00 comes before 01-Feb-2007 01:00:00"
echo $str;
?>

function get_random_number($min = 0, $max = 100)
{
return rand($min,$max);
}

Chuỗi ngẫu nhiên từ 1 mảng:

function get_random_string_from_list($list_of_words)
{
return $list_of_words[rand(0,sizeof($list_of_words)-1)];
}

Chuỗi ngẫu nhiên:

function get_random_string($length=6,$characters = "ABCDEFGHIJKLMNOPRQSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_")
{
$num_characters = strlen($characters) - 1;
while (strlen($return) < $length)
{
$return.= $characters[mt_rand(0,$num_characters)];
}
return $return;
}

Số float ngẫu nhiên:

function random_float ($min,$max)
{
return ($min + lcg_value() * (abs($max-$min)));
}

Hex Color ngẫu nhiên:

function get_random_hex_color($values = 'abcdef0123456789',$length=6)
{
$num_characters = strlen($characters) - 1;
while (strlen($code) < $length)
{
$return.= $characters[mt_rand(0,$num_characters)];
}
return '#'.$return;
}

File ngẫu nhiên từ một thư mục:

function get_random_file($dir)
{
while (false !== ($file = readdir($dir)))
{
$files[] = $file;
}
return $files[rand(0,sizeof($files)-1)];
}