checkdate can determine whether an output date is valid.

In actual work, we often need to detect data validation commonly used for user submission forms.

For example: Verify whether the time entered by the user is correct.

The syntax format of the function is as follows:

bool checkdate (int $month, int $day, int $year)

In the following example, we You can use a code to conduct experiments and write a real example. Try to see if there is February 29, 2011.

Return true if it is a valid time, return false if it is not a valid time.

<?php
var_dump(checkdate(12, 31, 2018));
var_dump(checkdate(2, 29, 2011));
?>

Output result:

bool(true)
bool(false)