PHP, Date-Time and Calendar functions


<?php



string|int|float|false date_sunset ( int $timestamp , 

                                                       int $returnFormat = SUNFUNCS_RET_STRING , 

                                            float|null $latitude = null , 

                                            float|null $longitude = null , 

                                            float|null $zenith = null , 

                                            float|null $utcOffset = null )





where, 



$timestamp = The timestamp of the day from which the sunset time is taken



$returnFormat = The constant to control the type of the result

                          ( SEE the below TABLE )



$latitude = The local LATITUDE

                  date.default_latitude: as set in the php.ini



$longitude = The local LONGITUDE

                    date.default_longitude: as set in the php.ini



$zenith = The angle between the center of the sun and a line 

                perpendicular to the surface of earth

               date.sunrise_zenith: as set in the php.ini

               ( SEE the below TABLE )



$utcOffset = The GMT/UTC offset Specified in hours



?>

$timestamp

The timestamp of the day from which the sunset time is taken.

$returnFormat

FORMAT CONSTANTS
CONSTANT	VALUE	RETURNED TYPE	EXAMPLE
SUNFUNCS_RET_STRING	1	STRING	14:30
SUNFUNCS_RET_DOUBLE	2	FLOAT	14.5
SUNFUNCS_RET_TIMESTAMP	0	INTEGER	TIMESTAMP
ed48

$latitude

The local LATITUDE or date.default_latitude: as set in the php.ini.

$longitude

The local LONGITUDE or date.default_longitude: as set in the php.ini.

$zenith

COMMON zenith ANGLES
ANGLE	DESCRIPTION	ABOUT
90°50'	The point where the sun becomes invisible	SUNSET
96°	Conventionally used to signify the end of dusk	CIVIL TWILIGHT
102°	The point at which the horizon ends being visible at sea	NAUTICAL TWILIGHT
108°	The point at which the sun ends being the source of any illumination	ASTRONOMICAL TWILIGHT
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Accommodate yourself as a privileged observer, stationed at a given point on the earth plane.

Consider tracing a vertical line, perpendicular to that plane.

The point of the celestial sphere, above his head, intercepted by this line is called ZENITH.

Z apr

SOLAR ZENITH ANGLE is the angle formed by the vertical line at the point of the earth's surface where the observer is and the line of sight passing through the Sun.

Imagine, that same vertical, extended in the opposite direction.

The point that intercepts, analogously, the celestial sphere is called NADIR.

N apr

* Illustrations from WIKIPEDIA!

$utfOffset

The GMT offset specified in hours.

$utfOffset is specified in hours and is ignored, if $format is SUNFUNCS_RET_TIMESTAMP.

Every call to a date/time function will generate a E_NOTICE if the time zone is not valid, and/or a E_STRICT or E_WARNING message if using the system settings or the TZ environment variable.

See also date_default_timezone_set function.

This function returns the sunset time in a specified $format on success or FALSE on failure.

One potential reason for failure is that the sun does not set at all, which happens inside the polar circles for part of the year.

The values of date.timezone, date.default_latitude, date.default_longitude and date.sunrise_zenith are defined in the php.ini configuration file and should be changed if necessary.

Otherwise, the values of $latitude, $longitude, and $zenith must be supplied to the desired location.

D apr

The section of php.ini where this can be done is shown below:


[PHP]



; . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .



[Date]

; Defines the default timezone used by the date functions

; http://php.net/date.timezone

;date.timezone =

date.timezone = 'America/Sao_Paulo'



; http://php.net/date.default-latitude

date.default_latitude = -23.5503948



; http://php.net/date.default-longitude

date.default_longitude = -46.634513



; http://php.net/date.sunrise-zenith

;date.sunrise_zenith = 90.583333



; http://php.net/date.sunset-zenith

;date.sunset_zenith = 90.583333



; . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

EXERCISE


<?php



setlocale(LC_ALL, "pt_BR.utf-8", "portuguese-brazil", "ptb");

date_default_timezone_set('America/Sao_Paulo');



$in_gt  = ini_get('date.timezone');

$df_lat = ini_get('date.default_latitude');

$df_lng = ini_get('date.default_longitude');

$df_dsz = ini_get('date.sunset_zenith');

// Get the values defined in php.ini



echo 'INTERNAL PARAMETERS:<br><br>';



echo 'Latitude: ' . $df_lat .'<br>Longitude: ' . $df_lng . '<br>Zenith: ' . $df_dsz;



$tstp = gettimeofday(true);



echo '<br><br>DATE SUNSET TYPE FORMATS:<br><br>';



echo 'FLOAT<br>' . $tstp . '<br><br>';



// $sunset_def = date_sunset($tstp);

// echo 'STRING<br>' . $sunset_def . '<br><br>';



$sunset_str = date_sunset($tstp, SUNFUNCS_RET_STRING);

echo 'STRING<br>' . $sunset_str . '<br><br>';



$sunset_dbl = date_sunset($tstp, SUNFUNCS_RET_DOUBLE);

echo 'FLOAT<br>' . $sunset_dbl . '<br><br>';



$sunset_tm = date_sunset($tstp, SUNFUNCS_RET_TIMESTAMP);

echo 'INTEGER<br>' . $sunset_tm . '<br><br>';



?>

EXERCISE


<?php



setlocale(LC_ALL, "en_US", "american", "american english", "american-english", "english-american", "english-us", "english-usa", "enu", "us", "usa"); 

date_default_timezone_set('America/New_York');



$tstp = gettimeofday(true);



echo '<br>Central Park, New York, NY, USA<br><br>CURRENT TIMESTAMP:<br>' . $tstp . '<br><br>';



$lat = 40.7828647;

$lng = -73.9675438;



$date = date(DATE_W3C, $tstp);



echo 'CURRENT DATE:<br>' . $date;



echo '<br><br>DATE SUNSET TYPE FORMATS:';



$sunset_str = date_sunset($tstp, SUNFUNCS_RET_STRING, $lat, $lng);

echo '<br><br>STRING<br>' . $sunset_str . '<br><br>';



$sunset_dbl = date_sunset($tstp, SUNFUNCS_RET_DOUBLE, $lat, $lng);

echo 'FLOAT<br>' . $sunset_dbl . '<br><br>';



$sunset_tm = date_sunset($tstp, SUNFUNCS_RET_TIMESTAMP, $lat, $lng);

echo 'INTEGER<br>' . $sunset_tm;



?>

EXERCISE


<?php



//Timezones with required data for date_sunrise

$inputs = array (

//Timezone with Latitude, Longitude and GMT offset

"Pacific/Samoa" => 

array ("Latitude" => -14.24, "Longitude" => -170.72, "GMT" => -11),

"US/Alaska" => 

array ("Latitude" => 61, "Longitude" => -150 , "GMT" => -9),

"America/Chicago" => 

array ("Latitude" => 41.85, "Longitude" => -87.65 , "GMT" => -5),

"America/Montevideo" => 

array ("Latitude" => -34.88, "Longitude" => -56.18 , "GMT" => -3),

"Africa/Casablanca" => 

array ("Latitude" => 33.65, "Longitude" => "-7.58", "GMT" => 0),

"Europe/Moscow" => 

array ("Latitude" => 55.75, "Longitude" => 37.58, "GMT" => 4),

"Asia/Hong_Kong" => 

array ("Latitude" => 22.28, "Longitude" => 114.15 , "GMT" => 8),

"Australia/Brisbane" => 

array ("Latitude" => -27.46, "Longitude" => 153.2 , "GMT" => 10),

"Pacific/Wallis" => 

array ("Latitude" => -13.3, "Longitude" => -176.16, "GMT" => 12),

);



foreach($inputs as $timezone => $value) {

echo "<br><br>$timezone<br>";

date_default_timezone_set($timezone);

$time = mktime(8, 8, 8, 8, 11, 2008);

var_dump( date_sunset($time, SUNFUNCS_RET_STRING, 

$value["Latitude"], $value["Longitude"], 90, $value["GMT"] ));

$time = mktime(8, 8, 8, 8, 12, 2008);

var_dump( date_sunset($time, SUNFUNCS_RET_STRING, 

$value["Latitude"], $value["Longitude"], 90, $value["GMT"]) );

}



?>