In PHP, there are mainly the following methods to obtain the day of the week: 1. Use the date() function to combine format characters (such as 'w', 'N', 'l', 'D') to directly return the value or name of the day of the week; 2. Use the DateTime class to implement more flexible date processing, and support advanced functions such as time zones; 3. Use strtotime() to process custom date strings, which are suitable for database, user input and other scenarios; 4. Encapsulate helper functions to implement code reuse and simplify calls. These methods can be selected and used according to specific needs.

If you're working with dates in PHP and need to get the day of the week from a date, there are a few straightforward ways to do it. PHP provides built-in functions that make this task simple, whether you want the numeric representation (like 0 for Sunday or 1 for Monday), or the actual name (like "Monday").

Using date() with a Timestamp

The most common way to get the day of the week is by using the date() function. You can use different format characters depending on what you need:

• 'w' — returns the numeric day of the week (0 = Sunday, 1 = Monday, ..., 6 = Saturday)
• 'N' — returns the ISO-8601 numeric day of the week (1 = Monday, ..., 7 = Sunday)
• 'l' (lowercase L) — returns the full textual representation (eg, "Monday")
• 'D' — returns the abbreviated textual version (eg, "Mon")

Example:

 echo date('l'); // Outputs something like "Wednesday"
echo date('D'); // Outputs "Wed"
echo date('w'); // Outputs "3" (if today is Wednesday)
echo date('N'); // Outputs "3" (if today is Wednesday)

This method works well when you're dealing with the current date or a known timestamp.

Using DateTime for More Flexibility

If you're working with more complex date handling or need to support different time zones, the DateTime class is a better choice. It's object-oriented and offers more control.

Here's how you can get the day of the week using DateTime :

 $date = new DateTime();
echo $date->format('l'); // Full name, eg, "Wednesday"

You can also use it with a specific date string:

 $date = new DateTime('2025-04-05');
echo $date->format('D'); // Outputs "Sat"

This approach is especially useful when you need to manipulate or compare dates in your application.

Handling Custom Dates and Formats

Sometimes you might have a date string from a form or a database and need to convert it to a day of the week. You can combine strtotime() with date() for this:

 $dateString = '2025-04-06';
$timestamp = strtotime($dateString);
echo date('l', $timestamp); // Outputs "Sun"

This works well for:

• Dates stored in a database
• User input dates
• API responses with date strings

Make sure the input date is in a format that strtotime() understands, like YYYY-MM-DD.

If you're not sure about the date format, you might want to validate it first or use DateTime::createFromFormat() for more control.

A Simple Helper Function

If you find yourself needing this functionality in multiple places, you can wrap it in a reusable function:

 function getDayOfWeek($dateString = 'now') {
    $timestamp = strtotime($dateString);
    return date('l', $timestamp);
}

echo getDayOfWeek('2025-04-05'); // Outputs "Saturday"

• You can change 'l' to 'D' , 'w' , or 'N' depending on the format you want.
• The default is 'now' , so if no date is passed, it uses the current date.

This function is lightweight and handy in templates or forms where you just need to display the day.

That's basically it. Whether you're formatting dates for display, checking business days, or validating schedules, getting the day of the week in PHP is pretty straightforward with these tools.

The above is the detailed content of php function to get the day of the week. For more information, please follow other related articles on the PHP Chinese website!