Working with Dates and Times in PHP

In PHP, working with dates and times is a common task that can be accomplished using various functions and classes. One of the most useful functions for this purpose is date_create(), which creates a new DateTime object representing the current date and time.

To get the current date and time in the format "YYYY-MM-DD HH:MM:SS", you can use the following code:

$now = date_create()->format('Y-m-d H:i:s');

This will output a string like "2023-03-01 12:00:00".

The date_create() function accepts an optional parameter, which is the date and time to be represented by the object. If this parameter is not provided, the function uses the current date and time.

Another way to get the current date and time is using the new DateTime() constructor:

$now = new DateTime();
$currentTime = $now->format('Y-m-d H:i:s');

However, when working with namespaces, it’s recommended to use the date_create() function instead of the new DateTime() constructor to avoid potential issues.

The DateTime class provides various methods for manipulating dates and times, such as adding or subtracting intervals, and setting specific dates and times. For example:

$tomorrow = date_create('+1 day')->format('Y-m-d H:i:s');

This will output the date and time for tomorrow.

When working with time zones, it’s essential to consider the default time zone set in your PHP configuration. You can change the time zone using the date_default_timezone_set() function:

date_default_timezone_set('Asia/Tokyo');
$now = date_create()->format('Y-m-d H:i:s');

Alternatively, you can specify the time zone when creating a new DateTime object:

$nowLongyearbyen = date_create('now', timezone_open('Arctic/Longyearbyen'))->format('Y-m-d H:i:s');

In terms of performance, the date() function is slightly faster than date_create()->format(). However, the difference is only noticeable when creating millions of objects. For most use cases, the date_create()->format() approach provides more flexibility and readability.

Here’s a benchmark test that demonstrates the performance difference:

$start = time();
for ($i = 0; $i <= 5000000; $i++) {
    $a = date_create('now')->format('Y-m-d H:i:s');
}
$end = time();                  
$elapsedTimeA = $end - $start;
 
echo 'Case date_create(), elapsed time in seconds: ' . $elapsedTimeA;
echo '<br>';
 
$start = time();
for ($i = 0; $i <= 5000000; $i++) {
    $b = date('Y-m-d H:i:s');
}
$end = time();                   
$elapsedTimeB = $end - $start;
 
echo 'Case date(), elapsed time in seconds: ' . $elapsedTimeB;

In summary, when working with dates and times in PHP, the date_create()->format() approach provides a flexible and readable way to create and manipulate DateTime objects. While it may be slightly slower than the date() function, the difference is only noticeable in extreme cases.