php check for a valid date, weird date conversions

Question

Is there a way to check to see if a date/time is valid you would think these would be easy to check:

$date = \'0000-00-00\';
$time = \'00:00:00\';
$dateTime          


        

Answer 1

Don't expect coherent results when you're out of range:

cf strtotime

cf Gnu Calendar-date-items.html

"For numeric months, the ISO 8601 format ‘year-month-day’ is allowed, where year is any positive number, month is a number between 01 and 12, and day is a number between 01 and 31. A leading zero must be present if a number is less than ten."

So '0000-00-00' gives weird results, that's logical!

---

"Additionally, not all platforms support negative timestamps, therefore your date range may be limited to no earlier than the Unix epoch. This means that e.g. %e, %T, %R and %D (there might be more) and dates prior to Jan 1, 1970 will not work on Windows, some Linux distributions, and a few other operating systems."

cf strftime

---

Use checkdate function instead (more robust):

month: The month is between 1 and 12 inclusive.

day: The day is within the allowed number of days for the given month. Leap year s are taken into consideration.

year: The year is between 1 and 32767 inclusive.

Answer 2

<?php
function is_valid_date($user_date=false, $valid_date = "1900-01-01") {
    $user_date = date("Y-m-d H:i:s",strtotime($user_date));
    return strtotime($user_date) >= strtotime($valid_date) ? true : false;
}

echo is_valid_date("00-00-00") ? 1 : 0;    // return 0

echo is_valid_date("3/5/2011") ? 1 : 0;    // return 1

Answer 3

From php.net

<?php
function isValidDateTime($dateTime)
{
    if (preg_match("/^(\d{4})-(\d{2})-(\d{2}) ([01][0-9]|2[0-3]):([0-5][0-9]):([0-5][0-9])$/", $dateTime, $matches)) {
        if (checkdate($matches[2], $matches[3], $matches[1])) {
            return true;
        }
    }

    return false;
}
?>

Answer 4

As mentioned here: https://bugs.php.net/bug.php?id=45647

There is no bug here, 00-00-00 means 2000-00-00, which is 1999-12-00, which is 1999-11-30. No bug, perfectly normal.

And as shown with a few tests, rolling backwards is expected behavior, if a little unsettling:

>> date('Y-m-d', strtotime('2012-03-00'))
string: '2012-02-29'
>> date('Y-m-d', strtotime('2012-02-00'))
string: '2012-01-31'
>> date('Y-m-d', strtotime('2012-01-00'))
string: '2011-12-31'
>> date('Y-m-d', strtotime('2012-00-00'))
string: '2011-11-30'