(PHP 4 >= 4.1.0, PHP 5, PHP 7)
cal_info — Returns information about a particular calendar
$calendar = -1
  ] )
   cal_info() returns information on the
   specified calendar.
  
   Calendar information is returned as an array containing the
   elements calname, calsymbol,
   month, abbrevmonth and
   maxdaysinmonth. The names of the different calendars 
   which can be used as calendar are as follows:
   
CAL_GREGORIAN - Gregorian Calendar
     
    CAL_JULIAN - Julian Calendar
     
    CAL_JEWISH - Jewish Calendar
     
    CAL_FRENCH - French Revolutionary Calendar
     
    
   If no calendar is specified information on all
   supported calendars is returned as an array. 
  
calendarCalendar to return information for. If no calendar is specified information about all calendars is returned.
Example #1 cal_info() example
<?php
$info = cal_info(0);
print_r($info);
?>
The above example will output:
Array
(
    [months] => Array
        (
            [1] => January
            [2] => February
            [3] => March
            [4] => April
            [5] => May
            [6] => June
            [7] => July
            [8] => August
            [9] => September
            [10] => October
            [11] => November
            [12] => December
        )
    [abbrevmonths] => Array
        (
            [1] => Jan
            [2] => Feb
            [3] => Mar
            [4] => Apr
            [5] => May
            [6] => Jun
            [7] => Jul
            [8] => Aug
            [9] => Sep
            [10] => Oct
            [11] => Nov
            [12] => Dec
        )
    [maxdaysinmonth] => 31
    [calname] => Gregorian
    [calsymbol] => CAL_GREGORIAN
)