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Ruby: How to check if a string is a valid time?

Answer 1

+1 A:

You haven't exactly specified what you assume to be a valid time (e.g. whether you should accept optional seconds), so here's one guess:

data =~ /^([01]?[0-9]|2[0-3])\:[0-5][0-9]$/

Mladen Jablanović 2010-05-11 13:08:46

although Time.parse() with a rescue can work, I'd prefer the regex solution. Exceptions in ruby aren't considered really fast, so unless you need the time object, this is the advice I'd go with.

Dan Frade 2010-05-11 20:12:12

Using regex brings problems on its own: lots of different time formats making in very complicated to check whether the given time is valid. When you want to support all/most possible time formats you're basically reimplementing the `Time.parse()` method...

Veger 2010-05-12 08:20:31

All depends how strict you like to be when accepting values. I presumed maximum strictness (only optional thing being a leading zero in hours). The question doesn't specify. In addition to that, `Time.parse` seems to be really really liberal when it comes to arguments. Try, for example: `Time.parse '10'` and `Time.parse 'asd'`. Neither throws an exception (at least in 1.9.1). I really wouldn't rely on it.

Mladen Jablanović 2010-05-12 08:37:02

Answer 2

+4 A:

You can use Time.parse() and check for the ArgumentError exception for invalid times.

Extra advantage is that you also have the time in a usable format to work with if it is valid!

Veger 2010-05-11 13:14:50

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