regExp for HH:mm format including intermediate value

Question

I am trying to compose a regExp that accepts HH:mm time formats, but also accepts all of the intermediate values:

e.g. all of these are accepted:

For now, I came up with this: ^([\d]{1,2}):?([\d]{1,2})?$

But this accepts any numeric 1/2 digit values for hours and minutes (e.g. 25:66 is acceptable)

So I came relatively close to my goal, but I need to filter out values x>24 from the hours, and x>60 from the minutes?

Perhaps like this https://stackoverflow.com/questions/1494671/regular-expression-for-matching-time-in-military-24-hour-format — The fourth bird, Jun 18 '21 at 14:06
probably, you can build a regex pattern for your requirement. But, regex is not a good tool if you need to do math-calc. I suggest splitting the input by `:` and check the hour and minutes. It would be a lot easier. — Kent, Jun 18 '21 at 14:07

xGeo · Answer 1 · 2021-06-21T14:25:30.597

Try this:

^((?:[01][0-9]?)|(?:2[0-4]?)|(?:[3-9]))(?::((?:[0-5][0-9]?)|(?:60))|:)?$

NOTE:

This accepts 24 for HH and 60 for MM as stated in your question:

but I need to filter out values x>24 from the hours, and x>60 from the minutes?

Thus ff. are accepted:

and below are not accepted:

25:30
00:61

If you want to exclude 24 HH and 60 MM, try this instead:

^((?:[01]\d?)|(?:2[0-3]?))(?::|(?::([0-5][0-9]?)))?$

Groups (applies to both cases):

score 2 · Accepted Answer · answered Jun 18 '21 at 15:31

2

You are looking for

^(?:[01]\d?|2[0-3]?)(?::(?:[0-5]\d?)?)?$

Details:

^ - start of string
(?:[01]\d?|2[0-3]?) - either a 0 or 1 followed by an optional digit, or a 2 followed with an optional 0, 1, 2 or 3
(?::(?:[0-5]\d?)?)? - an optional sequence of patterns:
- : - a colon
- (?:[0-5]\d?)? - an optional sequence of patterns:
  - [0-5] - a digit from 1 to 5
  - \d? - an optional digit
$ - end of string.

answered Jun 18 '21 at 15:31

Wiktor Stribiżew

1

Thanks, excellent answer with the explanation as well <3 – Michael Vigato Jun 22 '21 at 09:14