Regex to replace multiple occurence of @ except first

Question

I have an email "xyz@gmail@.com", which contains two @ characters. What I want is to keep the first @ character and remove all the remaining 2 characters (even if there are more than two @ characters in email).

What I had tried to do is:

Regex.Replace("xyz@gmail@.com", @"^([^,]*@[^,]*)@(.*)$", "")

but it is returning empty string. I am not sure how to replace the 2nd character, even I am not sure if I have correctly chosen the regex pattern.

Answer 1

You may use

var result = Regex.Replace(text, @"(?<!^[^@]*)@", "");

See the regex demo . Details:

• (?<!^[^@]*) - a negative lookbehind that makes sure there is no @ before the current location up to the string start
• @ - a @ in other contexts.

In case you do not really have to use a regex,

var result = text.Substring(0, text.IndexOf("@")+1) + text.Substring(text.IndexOf("@")+1).Replace("@", "");

should also work. See the C# demo .

Answer 2

Regex will only match one occurrence, you can do this without regex though:

var parts = text.Split("@");
var result = parts[0] + "@" + string.Join("", parts.Skip(1));