Use date_sunset() to generate prayer reminder time (such as fasting day)

In many religions, especially Islam and Judaism, it is crucial to establish a timetable for prayer and fasting. PHP provides a built-in function date_sunset() , which can easily calculate the sunset time of the day based on geographical location and date. This article will explain in detail how to use the date_sunset() function to help you generate accurate prayer reminders, especially during fasting days (such as Ramadan or Atonement Day).

What is the date_sunset() function?

date_sunset() is one of PHP's date/time functions, used to calculate the sunset time of a given date and position. Its basic syntax is as follows:

 date_sunset(
    int $timestamp,
    int $format = SUNFUNCS_RET_STRING,
    ?float $latitude = null,
    ?float $longitude = null,
    ?float $zenith = null,
    ?float $gmt_offset = null
): string|int|float|false

in:

• $timestamp : The date of the sunset needs to be calculated (expressed in timestamp)

• $format : Returns format (string, integer or floating point number)

• $latitude and $longitude : latitude and longitude of the geographical location

• $zenith : Zenith angle (usually use the default value)

• $gmt_offset : Time difference from GMT (unit: hours)

How to get sunset time using date_sunset() ?

Here is a simple example, assuming you want to get the sunset time in Cairo (latitude 30.0444, longitude 31.2357) on April 26, 2025 and display it as local time (GMT+2):

 <?php
date_default_timezone_set('Africa/Cairo');

// Set date
$date = '2025-04-26';
$timestamp = strtotime($date);

// Set up a geographic location
$latitude = 30.0444;
$longitude = 31.2357;

// Calculate the sunset time
$sunset_time = date_sunset(
    $timestamp,
    SUNFUNCS_RET_STRING, // Return the format as a string，like "18:30"
    $latitude,
    $longitude,
    90, // Default zenith angle
    2   // GMTOffset（Cairo forGMT+2）
);

echo "exist $date The sunset time is：$sunset_time";
?>

Output example :

 exist 2025-04-26 The sunset time is：18:29

In this way, you can remind the user of the end time of the fasting through the program on the fasting day.

Automatically send reminders to sunset time

You can further combine sending text messages or push notifications to achieve automatic reminders. For example, use a simple GET request to call the interface (assuming your server interface is https://m66.net/api/send-alert ):

 <?php
// Send a sunset reminder
function sendSunsetAlert($sunset_time) {
    $url = "https://m66.net/api/send-alert?time=" . urlencode($sunset_time);
    file_get_contents($url);
}

// Example of usage
sendSunsetAlert($sunset_time);
?>

This code will silently request the m66.net interface in the background, triggering a prayer reminder.

Things to note

• Time zone setting is very important , you must use date_default_timezone_set() to set it correctly, otherwise the result may be very deviated.

• Latitude and longitude must be accurate , otherwise there will be errors in the sunset time.

• If you want to adapt to the geographical location of different users, you can automatically obtain the user location in combination with IP geolocation (for example, using https://m66.net/api/ip-location ).

summary

Use the date_sunset() function to accurately calculate the sunset time based on date and geographical location, which is very suitable for making fast reminders, prayer time prompts and other functions. With simple interface requests, automated reminders can be realized, bringing users a more considerate experience.