Question

How can I write a c# regular expression to use for replacing an ampersand (&) with consideration that the ampersand occurrence could be in & > © or AT&T

For example… Regex.Replace(“(\S)&(\S![^;])”, “$1&$2”);

Answer 1

To directly replace "&" with "& you don’t need a regex, just use String.Replace (or StringBuilder.Replace).

However to replace "&" where it isn’t followed by a "amp;" does need a regex, and a “Zero-width negative lookahead assertion“:¹

var result = Regex.Replace(input, "&(?!amp;)", "&");

¹ The reason to use a zero-width assertion is to handle "&" at the end of the string.