Поиск подстроки в строке по маске

string text = @"Historically, the world of data and the world of objects" +
          @" have not been well integrated. Programmers work in C# or Visual Basic" +
          @" and also in SQL or XQuery. On the one side are concepts such as classes," +
          @" objects, fields, inheritance, and .NET Framework APIs. On the other side" +
          @" are tables, columns, rows, nodes, and separate languages for dealing with" +
          @" them. Data ....bla bla bla";
 
        string searchTerm = "data";
 
        string[] source = text.Split(new char[] { '.', '?', '!', ' ', ';', ':', ',' }, StringSplitOptions.RemoveEmptyEntries);
 
           var matchQuery = from word in source
                         where word.ToLowerInvariant() == searchTerm.ToLowerInvariant()
                         select word;
 
        int wordCount = matchQuery.Count();
        Console.WriteLine("{0} occurrences(s) of the search term \"{1}\" were found.", wordCount, searchTerm);
        Console.WriteLine("Press any key to exit");
        Console.ReadKey();

using System.Text;
using System.Text.RegularExpressions;

string text = "hello hell shallow hippo";
string paterrn = @"(?<=([^\w]|^))([Hh]\w*[o])(?=([^\w]|$))";
for (var m = Regex.Match(text, paterrn); m.Success; m = m.NextMatch())
{
    Console.WriteLine(m.Value);
}