Regex only allow dash in between characters

March 1, 2022

I have this regex ^[A-ZÆØÅa-zæøå\ \-]{2,50}$ for validating names. How can I make it allow only one "-". I want it to accept names like this:

Janet Smith-Johnson
Mary-Ann Johnson
Sara Mary John-Smith
Sara Johnson
Sara Mary Johnson

But it can’t allow names that starts with - and ends with -. Like:

-Janet Mary
Mary-

>Solution :

You can use

^(?=.{2,50}$)(?!(?:.*-){2})[A-ZÆØÅa-zæøå]+(?:[- ][A-ZÆØÅa-zæøå]+)*$

See the regex demo.

If you are using the regex in C# or with u flag in JavaScript that supports ECMAScript 2018+ standard, you can also match any Unicode letter with \p{L}:

^(?=.{2,50}$)(?!(?:.*-){2})\p{L}+(?:[- ]\p{L}+)*$

Details:

^ – start of string
(?=.{2,50}$) – two to fifty chars in the string allowed
(?!(?:.*-){2}) (or (?!(?:[^-]*-){2}) in the real code is more efficient) – no two hyphens are allowed
[A-ZÆØÅa-zæøå]+ – one or more letters from the set (\p{L} matches any Unicode letter)
(?:[- ][A-ZÆØÅa-zæøå]+)* – zero or more sequences of either space or - and then one or more letters
$ – end of string.