What is timestamp?#
A timestamp is the number of seconds from January 1, 1970 at 00:00.
<?php
//output number of seconds from Jan 1, 1970 at 00:00.
echo time();
echo date("d/m/y")."\n";
$now = getdate();
echo $now["hours"]+8;
//print_r ($now);
// 'z' is indexed from 0, so it is necessary to add 1.
$numDays = date("z", mktime(0,0,0,12,31,2020))+1;
$numWeeks = date("W", mktime(0,0,0,12,31,2020));
echo "There are $numDays days and $numWeeks weeks in 2020.\n";
How to display the current date/time?#
<?php
// get current date and time
// getdate() returns an array of values
// notice that the 0th element of the array returned by getdate() contains a UNIX timestamp
$now = getdate();
// turn it into strings
$currentTime = $now["hours"]+6 . ":" . $now["minutes"] .":" . $now["second"];
$currentDate = $now["mday"] . "." . $now["mon"] . "." . $now["year"];
// result: "It is now 12:37:47 on 30.10.2006"
echo "It is now $currentTime on $currentDate";
Important Full Date and Time#
| Parameters | Description |
|---|
| r | Displays the full date, time and timezone offset. It is equivalent to manually entering date(“D, d M Y H:i:s O”) |
Time#
| Parameters | Description |
|---|
| a | am or pm depending on the time |
| A | AM or PM depending on the time |
| g | Hour without leading zeroes. Values are 1 through 12 |
| G | Hour in 24-hour format without leading zeroes. Values are 0 through 23 |
| h | Hour with leading zeroes. Values 01 through 12 |
| H | Hour in 24-hour format with leading zeroes. Values 00 through 23 |
| i | Minute with leading zeroes. Values 00 through 59 |
| s | Seconds with leading zeroes. Values 00 through 59 |
Day#
| Parameters | Description |
|---|
| d | Day of the month with leading zeroes. Values are 01 through 31 |
| j | Day of the month without leading zeroes. Values 1 through 31 |
| D | Day of the week abbreviations. Sun through Sat |
| l | Day of the week. Values Sunday through Saturday |
| w | Day of the week without leading zeroes. Values 0 through 6 |
| z | Day of the year without leading zeroes. Values 0 through 365 |
Month#
| Parameters | Description |
|---|
| m | Month number with leading zeroes. Values 01 through 12 |
| n | Month number without leading zeroes. Values 1 through 12 |
| M | Abbreviation for the month. Values Jan through Dec |
| F | Normal month representation. Values January through December |
| t | The number of days in the month. Values 28 through 31 |
Year#
| Parameters | Description |
|---|
| L | 1 if it’s a leap year and 0 if it isn’t |
| Y | A four digit year format |
| y | A two digit year format. Values 00 through 99 |
| Parameters | Description |
|---|
| U | The number of seconds since the Unix Epoch (January 1, 1970) |
| O | This represents the Timezone offset, which is the difference from Greenwich Meridian Time (GMT). 100 = 1 hour, -600 = -6 hours |
How to turn a UNIX timestamp into a human-readable string?#
<?php
// get date
// result: "30 Oct 2006" (example)
echo date("d M Y"). " <br>";
// get time
// result: "12:38:26 PM" (example)
echo date("h:i:s A"). " <br>";
// get date and time
// result: "Monday, 30 October 2006, 12:38:26 PM" (example)
echo date ("l, d F Y, h:i:s A") . " <br>";
// get time with timezone
// result: "12:38:26 PM UTC"
echo date ("h:i:s A T") . " <br>";
// get date and time in ISO8601 format
// result: "2006-10-30T12:38:26+00:00"
echo date ("c");
?>
<?php
// define number of minutes
$mm = 156;
// convert to hh:mm format
// result: "02h 36m"
echo sprintf("%02dh %02dm", floor($mm/60), $mm%60);
?>
<?php
// define hours and minutes
$hhmm = "02:36";
// convert to minutes
// result: "156 minutes"
$arr = explode(":", $hhmm);
echo $arr[0]*60 + $arr[1] . " minutes";
?>
How to convert local time to Greenwich Mean Time (GMT)?#
<?php
// convert current local time (IST) to GMT
// result: "15:06:25 30-Oct-06 GMT" (example)
echo gmdate("H:i:s d-M-y T") . "<br>";
// convert specified local time (IST) to GMT
// result: "23:00:00 01-Feb-05 GMT" (example)
$ts = mktime(4,30,0,2,2,2005);
echo gmdate("H:i:s d-M-y T", $ts);
?>
How to obtain the local time in another time zone, given its GMT offset?#
<?php
// set default time zone to destination
// result: "00:11:26 31-10-06 SST"
date_default_timezone_set('Asia/Singapore');
echo date("H:i:s d-m-y") . " SST \n";
// set default time zone to destination
// result: "08:11:26 30-10-06 PST"
date_default_timezone_set('US/Pacific');
echo date("H:i:s d-m-y") . " PST \n";
?>
Reference#
- PHP dates and times