Date regular expression gives error

I have been working on my date regular 开发者_StackOverflowexpression all day... I want a date format to be YYYY-MM-DD.

$date_regex ='^(19|20)\d\d[- /.](0[1-9]|1[012])[- /.](0[1-9]|[12][0-9]|3[01])$';

if (preg_match($date_regex, $dateString)) {
        echo "good format";
    }

keeps giving me error

preg_match() [function.preg-match]: No ending delimiter '^' found in test.php on line 19

Anyone help?? Thanks a lot!!

You need to wrap your regular expression in a pair of delimiting characters. Also, you need to escape the dashes in your character classes using \.

Try this (I'm using # as a delimiter):

$date_regex ='#^(19|20)\d\d[\- /.](0[1-9]|1[012])[\- /.](0[1-9]|[12][0-9]|3[01])$#';

You need to include the /s otherwise the regex thinks you are limiting it with the ^

'/^(19|20)\d\d[- /.](0[1-9]|1[012])[- /.](0[1-9]|[12][0-9]|3[01])$/'

Regards