从PHP 5.2.0开始，你可以使用DateTime()类:

use \Datetime;

$now = new DateTime();
echo $now->format('Y-m-d H:i:s');    // MySQL datetime format
echo $now->getTimestamp();           // Unix Timestamp -- Since PHP 5.3

并指定时区:

$now = new DateTime(null, new DateTimeZone('America/New_York'));
$now->setTimezone(new DateTimeZone('Europe/London'));    // Another way
echo $now->getTimezone();

下面是一些常用的表示时间的字符:

H -以前导零表示的12小时格式(01到12) i -前导0的分钟(00到59) s -前导0的秒(00到59) a -小写的子午线前后(am或pm)

确定你的时区

<?php
    date_default_timezone_set("America/New_York");
    echo "The time is " . date("h:i:sa");
?>

看看这个(可选)

<?php
    $d = mktime(11, 14, 54, 8, 12, 2014);
    echo "Created date is " . date("Y-m-d h:i:sa", $d);
?>

为日期

<?php
    echo "Today is " . date("Y/m/d") . ;
    echo "Today is " . date("Y.m.d") . ;
    echo "Today is " . date("Y-m-d") . ;
    echo "Today is " . date("l");
?>

下面是一些常用来表示日期的字符:

d -表示一个月中的第一天(01 ~ 31) m -代表一个月(01 ~ 12) Y -年份(四位数) l(小写“l”)-代表星期几

Source-W3-Schools

 $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。

非常简单的

date_default_timezone_set('Asia/Kolkata');
$date = date('m/d/Y H:i:s', time());

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

<?php
// Assuming today is March 10th, 2001, 5:16:18 pm, and that we are in the
// Mountain Standard Time (MST) Time Zone

$today = date("F j, Y, g:i a");                 // March 10, 2001, 5:16 pm
$today = date("m.d.y");                         // 03.10.01
$today = date("j, n, Y");                       // 10, 3, 2001
$today = date("Ymd");                           // 20010310
$today = date('h-i-s, j-m-y, it is w Day');     // 05-16-18, 10-03-01, 1631 1618 6 Satpm01
$today = date('\i\t \i\s \t\h\e jS \d\a\y.');   // it is the 10th day.
$today = date("D M j G:i:s T Y");               // Sat Mar 10 17:16:18 MST 2001
$today = date('H:m:s \m \i\s\ \m\o\n\t\h');     // 17:03:18 m is month
$today = date("H:i:s");                         // 17:16:18
$today = date("Y-m-d H:i:s");                   // 2001-03-10 17:16:18 (the MySQL DATETIME format)
?>