checkdate Validate a Gregorian date boolcheckdate intmonth intday intyear Returns &true; if the date given is valid; otherwise returns &false;. Checks the validity of the date formed by the arguments. A date is considered valid if: year is between 1 and 32767 inclusive month is between 1 and 12 inclusive Day is within the allowed number of days for the given month. Leap years are taken into consideration. ]]> The above example will output: See also mktime and strtotime.