C# 4 and .NET 4

222 ❘ ChaPTer 9 strinGs And reGulAr expressiOns
but a match on the final word data would display g of data. (only one character after the match), because
after that you get to the end of the string. This longer string lets you see more clearly where the regular
expression locates the match:
static void WriteMatches(string text, MatchCollection matches)
{
Console.WriteLine("Original text was: \n\n" + text + "\n");
Console.WriteLine("No. of matches: " + matches.Count);
}
foreach (Match nextMatch in matches)
{
int index = nextMatch.Index;
string result = nextMatch.ToString();
int charsBefore = (index < 5) index: 5;
int fromEnd = text.Length-index-result.Length;
int charsAfter = (fromEnd < 5) fromEnd: 5;
int charsToDisplay = charsBefore + charsAfter + result.Length;
}
Console.WriteLine("Index: {0}, \tString: {1}, \t{2}",
index, result,
text.Substring(index-charsBefore, charsToDisplay));
The bulk of the processing in this method is devoted to the logic of figuring out how many characters in the
longer substring it can display without overrunning the beginning or end of the input text. Note that you
use another property on the Match object, Value, which contains the string identified for the match. Other
than that, RegularExpressionsPlayaround simply contains a number of methods with names such as
Find1, Find2, and so on, which perform some of the searches based on the examples in this section. For
example, Find2 looks for any string that contains a at the beginning of a word:
static void Find2()
{
string text = @"This comprehensive compendium provides a broad and thorough
investigation of all aspects of programming with ASP.NET. Entirely revised and
updated for the 3.5 Release of .NET, this book will give you the information
you need to master ASP.NET and build a dynamic, successful, enterprise Web
application.";
string pattern = @"\ba";
MatchCollection matches = Regex.Matches(text, pattern,
RegexOptions.IgnoreCase);
WriteMatches(text, matches);
}
Along with this comes a simple Main() method that you can edit to select one of the Find() methods:
static void Main()
{
Find1();
Console.ReadLine();
}
The code also needs to make use of the RegularExpressions namespace:
using System;
using System.Text.RegularExpressions;
Running the example with the Find2() method shown previously gives these results:
RegularExpressionsPlayaround
Original text was:
This comprehensive compendium provides a broad and thorough investigation of all
aspects of programming with ASP.NET. Entirely revised and updated for the 3.5
www.it-ebooks.info