Regex pattern for HH:MM:SS time string

Question

I want to parse a hh:mm:ss string. A simple one is ([0-1]?\\d|2[0-3]):([0-5]?\\d):([0-5]?\\d) which expects 2:3:24 or 02:03:24<

Answer 1

@Tim Pietzcker covers the OP's requirement for a HH:MM:SS parser where SS was mandatory, i.e.

• HH:MM:SS
• MM:SS
• SS

If you permit me to deviate from the OP's requirement for a bit, and consider a case where HH is mandatory, i.e.

• HH
• HH:MM
• HH:MM:SS

The regex I came up with was:

^([0-1]?\d|2[0-3])(?::([0-5]?\d))?(?::([0-5]?\d))?$

Let's break it down:

• ([0-1]?\d|2[0-3]) - matches for hours
• (?::([0-5]?\d))? - optionally matches for minutes
• (?::([0-5]?\d))? - optionally matches for seconds