Core PHP Programming: Using PHP to Build Dynamic Web Sites

Time and Date

All the time functions work off the UNIX epoch, which is January 1, 1970. Dates are expressed as seconds since the epoch. This makes it easy to refer to dates with integers. When a function calls for seconds since the epoch, I've referred to it as a timestamp.

boolean checkdate(integer month, integer day, integer year)

The checkdate function returns TRUE if a date is valid, FALSE otherwise. A day is considered valid if the year is between 0 and 32,767, the month is between 1 and 12, and lastly, if the day is within the allowable days for that month.

<?
     if(checkdate(2,18,1970))
     {
          print("It is a good day");
     }
?>

string date(string format, integer timestamp)

The date function returns a string describing the date of the timestamp ...