gregoriantojd

int gregoriantojd(int month, int day, int year) 

month	Gregorian calendar month number
day	Gregorian calendar day of month
year	Gregorian calendar year

Converts a Gregorian date to a Julian day count.

Returns:

Julian day count; 0 if any parameter is outside the valid range

Description:

gregoriantojd() converts a Gregorian calendar date to a Julian day count. If any parameter is set to a value outside of the acceptable range, the function returns 0.

The following table shows the acceptable ranges for the parameters of this function.

Parameter	Acceptable Range of Values
month	1 to 12
day	1 to 31
year	-4714 to at least 10000

To specify a B.C. date, use a negative value for the year parameter.

This function is fairly forgiving in one way. If the date specified is invalid for the month specified, but still falls between 1 and 31, the function returns a valid Julian day count. The count is for the month after the specified month, with the day of the month set to the specified day minus the actual number of days in the specified month. Try the following example:

$jd = gregoriantojd (2, 31, 2002); 
echo jdtogregorian ($jd); 

Output: 
3/3/2002 

Version:

3+, 4+

See also:

To convert a Julian day count to a Gregorian calendar date:

jdtogregorian() 

To convert a Julian day count to another calendar system, see the other jdto* functions.

Examples:

Display the number of days left until Christmas

// Parse the current month, day, and year out of a call to date () 
list ($month, $day, $year) = explode ('/', date ('m/d/Y')); 

echo gregoriantojd (12, 25, $year) - gregoriantojd ($month, $day, $year); 

Demonstrate how gregoriantojd() handles invalid month days

// Get a Julian day count for February 30th, 2003 
$julian_day = gregoriantojd (2, 30, 2003); 
echo "The Julian day count for February 30, 2003 is $julian_day.<br />"; 
// Find the proper date for $julian_day 
// Parse the date in separate values for $year and $day. 
// Discard the month data. 
list (, $day, $year) = explode ('/', jdtogregorian ($julian_day)); 
// Find the month name for $julian_day 
$month_name = jdmonthname ($julian_day, 1); 
echo "However, the proper date for this Julian day count is 
 actually $month_name $day, $year.";