The following RegEx extract the hour from a 24H time format string like HH:mm (09:30), HH (09), or H (9). ────────────── Explanation: • \b: Word boundary to ensure we capture only complete numbers, not parts of larger numbers. • (?:...): Non-capturing group to match the following alternatives without creating a capture group. • [01]\d: Matches hours from 0 to 19. • 2[0-3]: Matches hours from 20 to 23. • (?=:|$): Lookahead to ensure the hour is followed by a colon : (like in HH:mm) or the end of the string (like in H or HH).