Question

I need to identify a hour in a string in a Regex. The rules are the following:

• The hour is in the format of %m or %h:%m (by %x I mean xx or x);
• The hour should be till 31:59;
• Should NOT pass strings like 000, 25:545; :12;

So, my actual variant of Regex is (with ExplicitCapture option, I verify it here):

((?<hours>([012]*[0-9])|([3]*[01]))\:)*(?<minutes>[0-5]*[0-9])

The problem is that I don’t achieve to “limit” this string ($myregex^, surprisingly, stopped detecting a valid string). Any idea why?

Answer 1

Try this:

^((?<hours>([012]?\d)|(3[01])):)?(?<minutes>[0-5]?\d)$

You have some problems with your regex. Mostly, you’re using * where you shouldn’t. This opens the door to many errors. For example, it matches the string "0010203333333".