using System;
using System.Text.RegularExpressions;
public class Example
{
public static void Main()
{
string pattern = @"(\b|\s)(-{3})(\b|\s)";
string input = @"This- -is - a test-sentence. -Test- --- One-Two--Three---Four----.";
foreach (Match m in Regex.Matches(input, pattern))
{
Console.WriteLine("'{0}' found at index {1}.", m.Groups[2].Value, m.Index);
}
}
}
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