问题:

I'm currently using ([1-9]|1[0-2]) to represent inputs from 1 to 12. (Leading zeros not allowed.)

However it seems rather hacky, and on some days it looks outright dirty.

☞ Is there a proper in-built way to do it?

☞ What are some other ways to represent number ranges?

回答1:

I tend to go with forms like [2-9]|1[0-2]? which avoids backtracking, though it makes little difference here. I've been conditioned by XML Schema to avoid such "ambiguities", even though regex can handle them fine.

回答2:

Yes, the correct one:

[1-9]|1[0-2]

Otherwise you don't get the 10.

回答3:

You can use:

[1-9]|1[012]

回答4:

Here is the better answer, with exact match from 1 - 12.

(^0?[1-9]$)|(^1[0-2]$)

Previous answers doesn't really work well with HTML input regex validation, where some values like '1111' or '1212' will still treat it as a valid input.