在PHP中獲取日期的星期幾，主要有以下方法：1. 使用date()函數(shù)結(jié)合格式字符（如'w'、'N'、'l'、'D'）可直接返回星期幾的數(shù)值或名稱；2. 使用DateTime類實(shí)現(xiàn)更靈活的日期處理，支持時(shí)區(qū)等高級(jí)功能；3. 結(jié)合strtotime()處理自定義日期字符串，適用於數(shù)據(jù)庫(kù)、用戶輸入等場(chǎng)景；4. 封裝輔助函數(shù)以實(shí)現(xiàn)代碼復(fù)用和簡(jiǎn)化調(diào)用。這些方法可根據(jù)具體需求選擇使用。

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.

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