preg_match for dates

[neal]

ahhhh, regex; the one thing we all try our hardest to avoid despite their overwhelming power.

i got hold of a regex online from http://www.felgall.com/php17.htm and i want to match dates in the yyyy-mm-dd format.

the code below is just returning false every time, can anyone see why..?

Code:

$regexPattern = "^(19|20)\d{2}[\/\.- ](0?[1-9]|1[0-2])[\/\.- ](0?[1-9]|[12][0-9]|3[01])$";

    if(trim($postArray[$this->data]) != "") {
        if(!preg_match("/" . $regexPattern . "/", trim($postArray[$this->data]))) {
            return FALSE;
        } else {
            if($this->dataType == "time") {
                return (string) $this->data . ":00";
            } else {
            return (string) $this->data;
            }
        }
    } else {
        return FALSE;
    }

hmmm, just turned on error reporting & got

Warning: preg_match() [function.preg-match]: Compilation failed: range out of order in character class at offset 19

in the meantime, i shall google further...

[neal]

haha!

found the answer on a german site, i escaped the two - signs.

although it also accepts yyyy-mm-d as an acceptable format, how do i get it to always require double digit values for m & d?

[spannaa]

This:

Code:

(19|20)\d{2}-([0][0-9]|[1][0-2])-([0][0-9]|[1][0-9]|[2][0-9]|[3][0-1])

ought to do what you're after but this:

Code:

(19|20)\d{2}-(((0[13578]|(10|12))-(0[1-9]|[1-2][0-9]|3[0-1]))|(02-(0[1-9]|[1-2][0-9]))|((0[469]|11)-(0[1-9]|[1-2][0-9]|30)))

is better because it won't accept too may days in a month e.g. 2009-11-31 is rejected.

[JasonD]

But that still allows yyyy-02-29

Regex is not the way to do this. See checkdate().

[neal]

brilliant, cheers guys.

i've gone with the regex spannaa posted for now simply because this is the 3rd level of error interception on the date inputs. there's jquery date picker as the preferred option, then there's the handy "dates must be entered to this format" text in the label if the user has JS disabled, and finally the regex. there shouldn't be an issue with requiring the fallback as it's a small custom app being used by 15 people in my office.

i'll probably use checkdate at some point in the near future, but i haven't got time to modify the class at the moment.

thanks again