PHP date function analysis: How to determine what day of the week a certain day is?

PHP date function analysis: How to determine what day of the week a certain day is?

In daily development, date and time processing is often involved, and determining what day of the week a certain day is is a common requirement. PHP provides a wealth of date functions that can easily implement this function. This article will introduce how to use the PHP date function to determine the day of the week a certain day is, and give specific code examples.

1. Use the date() function to get the day of the week

The date() function in PHP can return a formatted string of date, which contains the day of the week information. Specifically, the "l" parameter of the date() function can return the complete name of the day of the week (such as Monday, Tuesday, etc.), and the "N" parameter can return the numerical representation of the day of the week (1 represents Monday, 7 represents Sunday).

The following is a sample code that shows how to use the date() function to get the day of the week a certain day is:

$date = "2022-01-01"; // The date to be judged
$day_of_week = date('N', strtotime($date));

switch($day_of_week) {
    case 1:
        echo "Monday";
        break;
    case 2:
        echo "Tuesday";
        break;
    case 3:
        echo "Wednesday";
        break;
    case 4:
        echo "Thursday";
        break;
    case 5:
        echo "Friday";
        break;
    case 6:
        echo "Saturday";
        break;
    case 7:
        echo "Sunday";
        break;
}

In the above code, a $date variable is first defined to represent the date to be judged, and then the date() function is used in conjunction with the strtotime() function to convert the date into a numerical representation of the day of the week, and finally the switch is used. The statement converts the number into a specific day of the week name for output.

2. Use the strftime() function to get the day of the week (Chinese display)

In addition to using the date() function, we can also use the strftime() function to get the Chinese display of the day of the week. The strftime() function can return the corresponding localized date and time information based on the given format string.

The following is a sample code that shows how to use the strftime() function to obtain the Chinese display of the day of the week for a certain day:

setlocale(LC_TIME, 'zh_CN.UTF-8'); // Set the localization environment to Chinese

$date = "2022-01-01"; // The date to be judged
$day_of_week = strftime('%A', strtotime($date));

echo $day_of_week;

In the above code, first set the localization environment to Chinese through the setlocale() function, and then use the strftime() function combined with the strtotime() function to convert the date into the name of the day of the week in Chinese format for output.

Conclusion

Through the above two methods, we can easily determine what day of the week a certain day is and display it accordingly. In actual development, choosing a suitable method to obtain the day of the week information according to the needs of the project will help improve development efficiency and code readability. Hope this article is helpful to you!

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