The calendar extension presents a series of functions to simplify converting between different calendar formats. The intermediary or standard it is based on is the Julian Day Count. The Julian Day Count is a count of days starting from January 1st, 4713 B.C. To convert between calendar systems, you must first convert to Julian Day Count, then to the calendar system of your choice. Julian Day Count is very different from the Julian Calendar! For more information on Julian Day Count, visit http://serendipity.magnet.ch/hermetic/cal_stud/jdn.htm. For more information on calendar systems visit http://genealogy.org/~scottlee/cal-overview.html. Excerpts from this page are included in these instructions, and are in quotes.
To get these functions to work, you have to compile PHP with --enable-calendar.
A versão para Windows do PHP tem suporte embutido para esta extensão. Você não precisa carregar nenhuma extensão adicional para utilizar essas funções.
As contantes abaixo são definidas por esta extensão e somente estarão disponíveis quando a extensão foi compilada com o PHP ou carregada dinamicamente durante a execução.
The following constants are available since PHP 4.3.0 :