Regex for only hours or hours and minutes

问题

I am using regex ^(([0-9])|([0-1][0-9])|([2][0-3])):(([0-9])|([0-5][0-9]))$ for time. It is very good regex but when user wants to enter only hours like 8 or 12 without colon and minutes it is not allowing. Can any one suggests which regular expressions suits hours only or hours:minutes.

回答1:

^(([0-9])|([0-1][0-9])|([2][0-3]))(:(([0-9])|([0-5][0-9])))?$

made the ":mm" part optional by putting it in () and adding a ? quantifier.

回答2:

Just make the last part optional, like this:

 ^(([0-9])|([0-1][0-9])|([2][0-3]))(:(([0-9])|([0-5][0-9])))?$

来源：https://stackoverflow.com/questions/11225981/regex-for-only-hours-or-hours-and-minutes