th Match the literal characters "th". : Regex Match « Regular Expression « C# / CSharp Tutorial

1. C# / CSharp Tutorial
2. Regular Expression
3. Regex Match

using System;
using System.Text.RegularExpressions;

public class Example
{
   public static void Main()
   {
      string pattern = @"\bth[^o]\w+\b";
      string input = "this is a test";
      foreach (Match match in Regex.Matches(input, pattern))
         Console.WriteLine(match.Value);
   }
}