我们可以使用date函数设置默认时区:

<?php
    date_default_timezone_set("Asia/Kolkata");
    echo "Today is " . date("Y/m/d") . "<br>";
    echo "Today is " . date("Y.m.d") . "<br>";
    echo "Today is " . date("Y-m-d") . "<br>";
    echo "Today is " . date("l");
    echo "The time is " . date("h:i:sa");
?>

如果你是孟加拉国人，如果你想知道达卡的时间，那么用这个:

$date = new DateTime();
$date->setTimeZone(new DateTimeZone("Asia/Dhaka"));
$get_datetime = $date->format('d.m.Y H:i:s');

// Set the default timezone to use. Available since PHP 5.1
date_default_timezone_set('UTC');


// Prints something like: Monday
echo date("l");

// Prints something like: Monday 8th of August 2016 03:12:46 PM
echo date('l jS \of F Y h:i:s A');

// Prints: July 1, 2016 is on a Saturday
echo "July 1, 2016 is on a " . date("l", mktime(0, 0, 0, 7, 1, 2016));

/* Use the constants in the format parameter */
// Prints something like: Wed, 25 Sep 2013 15:28:57 -0700
echo date(DATE_RFC2822);

// Prints something like: 2016-07-01T00:00:00+00:00
echo date(DATE_ATOM, mktime(0, 0, 0, 7, 1, 2000));

date_default_timezone_set('Europe/Warsaw');
echo("<p class='time'>".date('H:i:s')."</p>");
echo("<p class='date'>".date('d/m/Y')."</p>");

 $date = new DateTime('now', new DateTimeZone('Asia/Kolkata'));
 echo $date->format('d-m-Y H:i:s');

更新

 //Also get am/pm in datetime:
 echo $date->format('d-m-Y H:i:s a'); // output 30-12-2013 10:16:15 am

对于日期格式，PHP date() Function很有用。

Linux服务器时间与PHP time()时区差异如下:

<?php
    putenv("TZ=Asia/Kabul");
    $t = time();
    echo date('d/m/Y H:i:sa', $t);
?>