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In PHP, the date_sunset() function is used to get the sunset time of the specified date and location. It represents the sunset moment by returning a UTC timestamp, which can be easily converted to a specific date and time format. This function is very suitable for applications that require calculating solar activity time based on geographic location.
date_sunset(time, format, latitude, longitude, zenith, dst)
time (optional): This is an optional parameter indicating the timestamp to query. If not specified, date_sunset() will use the current time by default. You can get the current timestamp through the time() function.
format (optional): Specifies the returned sunset time format. Constants such as SUNFUNCS_RET_TIMESTAMP (returns Unix timestamps, defaults), SUNFUNCS_RET_DATE (returns date strings), SUNFUNCS_RET_STRING (returns time strings in "hh:mm:ss" format) can be used.
latitude : the latitude of the geographical location. The latitude value can be a negative or a positive number, representing the south and north latitudes, respectively.
longitude : the longitude of the geographical location. The longitude value can be a negative or a positive number, representing the West and East longitudes respectively.
zenith (optional): This value represents the zenith angle of the sun. The default value is 90.5, which usually represents the zenith angle that the sun considers to be "sunset". If you want to calculate more precise sunset times, you may need to adjust this value.
dst (optional): indicates daylight saving time, 1 is on and 0 is off. By default, the daylight saving time setting of the current system time is used.
Here is an example showing how to use the date_sunset() function to get the sunset time for a specific location:
<?php
// Set the query timestamp，Use the current time
$timestamp = time();
// Set the geographical location：latitude、longitude
$latitude = 40.7128; // 纽约的latitude
$longitude = -74.0060; // 纽约的longitude
// Get the sunset time in New York
$sunset = date_sunset($timestamp, SUNFUNCS_RET_STRING, $latitude, $longitude);
// Output sunset time
echo "The sunset time in New York is: " . $sunset;
?>
SUNFUNCS_RET_TIMESTAMP : Returns the Unix timestamp (integer) of sunset time.
SUNFUNCS_RET_DATE : Returns a formatted date string, such as Ymd .
SUNFUNCS_RET_STRING : Returns the time string, formatted in hh:mm:ss .
The date_sunset() function is usually used for geographic location-related applications, such as weather forecasts, astronomical applications, etc., especially when you need to understand sunshine periods and sunset times. For example, when writing a travel application, you may need to calculate the best time to take a photo based on where the user is located, or calculate the best time period for crop growth in agricultural applications.
Geographical location accuracy : Longitude and latitude values are very important, and incorrect values can lead to inaccurate sunset time calculations.
Daylight Saving Time Impact : In some areas, the opening and closing of Daylight Saving Time may affect the calculation of sunset time. Please set the dst parameters according to specific requirements.
The return type of function : Depending on the format parameter, the return value may be in different formats, and the returned data type needs to be processed according to specific needs.
By using the date_sunset() function, developers can easily obtain the sunset time of the specified location and date, providing accurate time data for weather, astronomy and other related applications.
