Regular expression

[chadrahul]

Regular expression to

accept only numbers with max 2 dashes (no 2 dashes together)
i.e.
123-345-567 YES
Or
-123345567- YES
Or
--123456789 NO
Or
As1234567 NO
Or
#355534gg NO
Etc.

[tlhintoq]

You couldn't even bother making your own effort first?
I see no code attempt to do this on your own before asking for help.

Here are some good RegEx resources
A Regular Expressions Reference
Online RegEx builder
Online RegEx tester