Regular expression to match phone number?

Question

I want to match a phone number that can have letters and an optional hyphen:

• This is valid: 333-WELL
• This is also valid: 4URGENT

Answer 1

Supposing that you want to allow the hyphen to be anywhere, lookarounds will be of use to you. Something like this:

^([A-Z0-9]{7}|(?=^[^-]+-[^-]+$)[A-Z0-9-]{8})$

There are two main parts to this pattern: [A-Z0-9]{7} to match a hyphen-free string and (?=^[^-]+-[^-]+$)[A-Z0-9-]{8} to match a hyphenated string.

The (?=^[^-]+-[^-]+$) will match for any string with a SINGLE hyphen in it (and the hyphen isn't the first or last character), then the [A-Z0-9-]{8} part will count the characters and make sure they are all valid.