using System;
using System.Text.RegularExpressions;
public class Example
{
public static void Main()
{
string pattern = @"<\s*(/?)\s*(?=(?:a|strong|em)\b)(\w+[^>]*)>";
string substitution = @"[\1\2]";
string input = @"<a href=""https://www.example.com/page"">Example page</a> is a <strong>valid</strong> tag.
< em class=""something""> is also allowed</em>
But <param> or <argument> should be escaped.
This also: <br/> <
br /> <script type=""text/javascript"">alert('xss'></script>
Turn left <- or turn right ->
Also, accept this => or a smiley >.<";
Regex regex = new Regex(pattern);
string result = regex.Replace(input, substitution);
}
}
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for C#, please visit: https://msdn.microsoft.com/en-us/library/system.text.regularexpressions.regex(v=vs.110).aspx