PHP and MySQL Web Development 4th Ed-tqw-_darksiderg

474 Chapter 21 Managing the Date and Time
Validating Dates with checkdate()
You can use the checkdate() function to check whether a date is valid.This capability
is especially useful for checking user input dates.The checkdate() function has the following
prototype:
int checkdate (int month, int day, int year)
It checks whether the year is a valid integer between 0 and 32,767, whether the month
is an integer between 1 and 12, and whether the day given exists in that particular
month.The function also takes leap years into consideration when working out whether
a day is valid.
For example,
checkdate(2, 29, 2008)
returns true, whereas
checkdate(2, 29, 2007)
does not.
Formatting Timestamps
You can format a timestamp according to the system’s locale (the web server’s local settings)
using the strftime() function.This function has the following prototype:
string strftime ( string $format [, int $timestamp] )
The $format parameter is the formatting code that defines how the timestamp will be
displayed.The $timestamp parameter is the timestamp that you pass to the function.This
parameter is optional. If no timestamp is passed as a parameter, the local system timestamp
(at the time the script is run) is used. For instance, the following code
displays the current system timestamp in four different formats.This code will produce
output similar to the following:
Friday
03/16/07
03/16/07 21:17:24
2007