C# Regex to match a Case Insensitive string that doesn't contain a certain string

Question

I want to match any string that does not contain the string "None" in any case (Case Insensitive Match),

I referred the question C# Regex to match a string that doesn't contain a certain string?

The said question gives the solution for a case sensitive, but I need to disallow the string "None" in any Case.

I need a generic regular expression for disallowing the string (Case Insensitive Match).

For Example:

• NONE
• None
• NoNe
• none
• nOnE
• NonE
• nONe, etc.,

Kindly assist me...

Answer 1

Use RegexOptions.IgnoreCase:

Regex.Matches( text, @"^(?!.*None).*$", RegexOptions.IgnoreCase );
Regex.IsMatch( text, @"^(?!.*None).*$" , RegexOptions.IgnoreCase );