2.17 PHP - Date & Time Functions Explained

Introduction to PHP Date and Time

Working with date and time is a common task in web development, whether you're displaying the current time, logging events, or manipulating dates for calculations. PHP provides robust built-in functions to handle date and time effectively.

In this blog, we’ll explore the basics of working with date and time in PHP, including formatting, manipulation, and best practices.

1. Getting the Current Date and Time

PHP’s date() function is commonly used to format and display the current date and time.

Syntax

date(format, timestamp);

• format: A string of characters specifying the format.
• timestamp: Optional. A Unix timestamp (default is the current time).

Example

echo date('Y-m-d H:i:s'); // Outputs current date and time in YYYY-MM-DD HH:MM:SS format

Output:

2025-01-12 14:35:45

2. Common Date Format Characters

Here are some commonly used format characters for the date() function:

3. Unix Timestamp

The Unix timestamp represents the number of seconds since January 1, 1970 (UTC). Use the time() function to get the current timestamp.

Example

$timestamp = time();
echo $timestamp; // Outputs current Unix timestamp

Convert a timestamp to a readable format using date():

echo date('Y-m-d', $timestamp); // Outputs the current date

4. Working with strtotime()

The strtotime() function parses a textual date description into a Unix timestamp.

Example

$dateString = "next Monday";
echo date('Y-m-d', strtotime($dateString)); // Outputs the date of the next Monday

Other Examples

echo date('Y-m-d', strtotime('yesterday'));
echo date('Y-m-d', strtotime('+1 week'));

5. Formatting Dates with DateTime

The DateTime class provides more advanced methods for handling dates and times.

Creating a DateTime Object

$date = new DateTime();
echo $date->format('Y-m-d H:i:s'); // Outputs the current date and time

Adding and Subtracting Dates

$date = new DateTime();
$date->add(new DateInterval('P7D')); // Add 7 days
echo $date->format('Y-m-d'); 

$date->sub(new DateInterval('P1M')); // Subtract 1 month
echo $date->format('Y-m-d');

6. Localizing Time with Timezones

PHP allows you to set and manage time zones using the date_default_timezone_set() function.

Example

date_default_timezone_set('America/New_York');
echo date('Y-m-d H:i:s'); // Outputs the current date and time in New York

Get the list of supported time zones:

print_r(timezone_identifiers_list());

7. Date and Time Validation

To validate dates, PHP offers the checkdate() function, which checks if a given date is valid.

Example

if (checkdate(2, 29, 2025)) {
    echo "Valid date.";
} else {
    echo "Invalid date.";
}

8. Formatting for Specific Use Cases

Display a Friendly Date

echo date('l, F j, Y'); // Outputs "Sunday, January 12, 2025"

Time Ago Format

$timestamp = strtotime('2025-01-01');
$diff = time() - $timestamp;

if ($diff < 60) {
    echo "$diff seconds ago";
} elseif ($diff < 3600) {
    echo round($diff / 60) . " minutes ago";
} elseif ($diff < 86400) {
    echo round($diff / 3600) . " hours ago";
} else {
    echo round($diff / 86400) . " days ago";
}

Conclusion

Working with date and time in PHP is essential for creating dynamic and user-friendly web applications. Whether you're displaying the current date, calculating time differences, or formatting timestamps, PHP provides a wide range of tools to handle these tasks efficiently.

Start experimenting with these functions to add powerful date and time features to your projects!