Regex for matching a character, but not when it's enclosed in square bracket

Question

Input string:

[Wsg-Fs]-A-A-A-Cgbs-Sg7-[Wwg+s-Fs]-A-A-Afk-Cgbs-Sg7

Desired output is a string array:

[Wsg-Fs] A A A Cgbs Sg7 [Wwg+s-Fs] A A Afk Cgbs Sg7

If I split the input string with - as delimiter, the string within square brackets also gets split.

How do I split the string such that - within square bracket should be ignored?

I could find some similar posts trying to ignore delimiter enclosed in quotes, however I have not been able to apply those solution to my problem.

Any suggestion would be really helpful. Thanks!

This post shows how to do it with CSV files having quotation marks; I imagine it could be adapted for square brackets: http://www.kimgentes.com/worshiptech-web-tools-page/2008/10/14/regex-pattern-for-parsing-csv-files-with-embedded-commas-dou.html — Robert Harvey, Aug 30 '12 at 20:10

score 9 · Accepted Answer · answered Aug 30 '12 at 20:10

Assuming there are no nested square brackets, you can use the following to only match - characters that are outside of square brackets:

-(?![^\[]*\])

Example: http://regex101.com/r/sX5hZ2

This uses a negative lookahead, with the logic that if there is a closing square bracket before any opening square brackets, then the - that we tried to match is inside of brackets.

score 2 · Answer 2 · edited May 23 '17 at 11:46

Resurrecting this ancient question to offer another solution, since the current one only checks that a splitting - is not followed by a ], which does not guarantee that it is enclosed in brackets.

\[[^\]]*\]|(-)

Then splitting on Group 1 (see the Group 1 captures in the bottom right panel of the demo)

To split on Group 1, we first replace Group 1 with something distinctive, such as SPLIT_HERE, then we split on SPLIT_HERE

using System;
using System.Text.RegularExpressions;
using System.Collections.Specialized;
class Program
{
static void Main() {
string s1 = @"[Wsg-Fs]-A-A-A-Cgbs-Sg7-[Wwg+s-Fs]-A-A-Afk-Cgbs-Sg7";
var myRegex = new Regex(@"\[[^\]]*\]|(-)");
var group1Caps = new StringCollection();

string replaced = myRegex.Replace(s1, delegate(Match m) {
if (m.Groups[1].Value == "") return m.Groups[0].Value;
else return "SPLIT_HERE";
});

string[] splits = Regex.Split(replaced,"SPLIT_HERE");
foreach (string split in splits) Console.WriteLine(split);

Console.WriteLine("\nPress Any Key to Exit.");
Console.ReadKey();

} // END Main
} // END Program

Here's a full working online demo

Reference

How to match pattern except in situations s1, s2, s3

How to match a pattern unless...

Regex for matching a character, but not when it's enclosed in square bracket

2 Answers2

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