C Sharp Find a Word

From Regex Regular Expression Encyclopedia

You can use this recipe for finding single words in a block of text. The expression will find only complete words surrounded by spaces or other word delimiters, such as punctuation or the beginning or end of a line.

[edit] code

using System;
using System.IO;
using System.Text.RegularExpressions;
public class Recipe
{
   private static Regex _Regex = new Regex( @"\bsomething\b" );
   public void Run(string fileName)
   {
      String line;
      int lineNbr = 0;
      using (StreamReader sr = new StreamReader(fileName))
      {
         while(null != (line = sr.ReadLine()))
         {
            lineNbr++;
            if (_Regex.IsMatch(line))
            {
              Console.WriteLine("Found match '{0}' at line {1}",
                 line,
                 lineNbr);
           }                                                               
        }
     }
  }
  public static void Main( string[] args )
  {
     Recipe r = new Recipe();
     r.Run(args[0]);
  }
}

[edit] How It Works

A special character class, \b, allows you to easily search for whole words. This is an advantage because without doing a whole bunch of extra work you can make sure that a search for some- thing, for example, doesn’t yield unexpected matches such as somethings. You can break the regular expression shown here into the following:

This expression differs just slightly from the C# and Visual Basic .NET examples because the RegularExpressionValidator control assumes that the expression is to match the entire value (there’s an implied ^ at the beginning of the expression and $ at the end of the expres- sion). The combination .* has been added before and after the word boundary \b so the full word can float around inside the line.