CODEWITHSUNDEEP
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KKS
KKS

Reputation: 3630

RegEx for dash and backtick, if included in a string, should have alphabets only at pre and post occurrence

[RegularExpression("^([a-zA-Z-`])+$", ErrorMessage = "Please correct your First Name - this should not contain any special characters other than - or `.")]
public string FirstName { get; set; }

I have the above regex pattern to allow users to input alphabets, dash and backtick only. However I am not able to create a pattern to only allow an alphabet to be followed by the dash or apostrophe. eg:

valid: sam`s, abd-cdf, dbc-dfd`s

invalid: sam``s, abcd--cef, dbf-`dfd, dbf`-dfd

How can I make sure that the above two special characters: dash and backtick , if included in a string, should have alphabets only at pre and post occurrence.

Upvotes: 0

Views: 660

Answers (3)

El Ronnoco
El Ronnoco

Reputation: 11912

You could use this

^([a-zA-Z]|(?<=[a-zA-Z])[`-])+$

Which will match any number of either

[a-zA-Z]

or

(?<=[a-zA-Z])[`-])

The second part uses a lookbehind which says that a backtick or - must be preceeded by one of the character class [a-zA-Z]

demo

Upvotes: 0

Adarsh Kumar
Adarsh Kumar

Reputation: 1150

Try this. It should work for you. Let me know if you have some other conditions as well.

^[a-zA-Z]+((`|-)[a-zA-Z]+)*$

Upvotes: 0

Jerry
Jerry

Reputation: 71578

First thing, you should avoid placing a dash (or hyphen) in between characters in a character class unless you want a range of characters. Since you want only backticks and hyphens, it would be better to use:

^[a-zA-Z`-]+$

Also, I don't think the capture group is necessary here.

On to the next requirement. You might want to use something like that:

^[a-zA-Z]+(?:[`-][a-zA-Z]+)*$

This is any number of letters, followed by either ` or - and a nother series of letters, and makes the backtick and hyphen appear only in the middle of the string.

regex101 demo

Upvotes: 1

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