What is the regex pattern for datetime (2008-09-01 12:35:45 )?

Question

What is the RegEx pattern for DateTime (2008-09-01 12:35:45 ) ?

I get this error:

No ending delimiter '^' found

Using:

preg_match('(?n:^(?=\d)((?<day>31(?!(.0?[2469]|11))|30(?!.0?2)|29(?(.0?2)(?=.{3,4}(1[6-9]|[2-9]\d)(0[48]|[2468][048]|[13579][26])|(16|[2468][048]|[3579][26])00))|0?[1-9]|1\d|2[0-8])(?<sep>[/.-])(?<month>0?[1-9]|1[012])\2(?<year>(1[6-9]|[2-9]\d)\d{2})(?:(?=\x20\d)\x20|$))?(?<time>((0?[1-9]|1[012])(:[0-5]\d){0,2}(?i:\ [AP]M))|([01]\d|2[0-3])(:[0-5]\d){1,2})?$)', '2008-09-01 12:35:45'); 

Gives this error:

Warning: preg_match() [function.preg-match]: Compilation failed: nothing to repeat at offset 0 in E:\www\index.php on line 19

Answer 1

@Espo: I just have to say that regex is incredible. I'd hate to have to write the code that did something useful with the matches, such as if you wanted to actually find out what date and time the user typed.

It seems like Tom's solution would be more tenable, as it is about a zillion times simpler and with the addition of some parentheses you can easily get at the values the user typed:

(\d{4})-(\d{2})-(\d{2}) (\d{2}):(\d{2}):(\d{2}) 

If you're using perl, then you can get the values out with something like this:

$year = $1; $month = $2; $day = $3; $hour = $4; $minute = $5; $second = $6; 

Other languages will have a similar capability. Note that you will need to make some minor mods to the regex if you want to accept values such as single-digit months.

Answer 2

A simple version that will work for the format mentioned, but not all the others as per @Espos:

(\d{4}-\d{2}-\d{2} \d{2}:\d{2}:\d{2})