How to remove a pattern that may or may not exist at the end using regex

Question

I want to capture without including a certain pattern (anything in parenthesis) that may or may not exist at the end of the string. I want to capture everything but the string \

Answer 1

You may use your matching approach with

^(.+?)(?:\(.*\))?$

See the regex demo. Basically, you need to add anchors to your pattern and use a lazy quantifier with the first dot matching pattern.

Details

• ^ - start of the string
• (.+?) - Group 1: one or more chars other than newline as few as possible (*? allows the regex engine to test the next optional subpattern first, and only expand this one upon no match)
• (?:\(.*\))? - an optional sequence of
  • \( - a ( char
  • .* - any 0+ chars other than newline as many as possible
  • \) - a ) char
• $ - end of string.

In C#:

var m = Regex.Match(s, @"^(.+?)(?:\(.*\))?$");
var result = string.Empty;
if (m.Success) {
    result = m.Groups[1].Value;
}

You may also remove a substring in parentheses at the end of the string if it has no other parentheses inside using

var res = Regex.Replace(s, @"\s*\([^()]*\)\s*$", "");

See another demo. Here, \s*\([^()]*\)\s*$ matches 0+ whitespaces, (, any 0+ chars other than ( and ) ([^()]*) and then 0+ whitespaces at the end of the string.