Regex only allow dash in between characters-CodePudding

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-

CodePudding user response：

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.

CodePudding user response：

You can match your character class without spaces, then optionally repeat a space and again use the character class without spaces.

Then optionally match - and the same mechanism again.

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

The pattern in parts matches:

^ Start of string
(?=.{2,50}$) Assert 2 - 50 characters
[A-ZÆØÅa-zæøå] Match what is listed in the character class without a space
(?: [A-ZÆØÅa-zæøå] )* Optionally repeat the character class preceded by a space
(?: Non capture group to match as a whole
- -[A-ZÆØÅa-zæøå] Match what is listed in the character class without a space
- (?: [A-ZÆØÅa-zæøå] )* Optionally repeat the character class preceded by a space
)? Close the non capture group and make it optional
$ End of string

Regex demo