James Mueller
Data Structures and Implementation
Unit 5 Individual Project
ITCO321 – 1103A - 02
August 21, 2011

Does the word matching exist in the phrase. In the phrase “There exists just a single example”, the word exam is indeed in this phrase. Exam is matched to the word Example as seen here. In order to for the word to be matched, using just plain vision was possible, however, in a computer sense; one must use a pattern matching string so that the program would be able to find the match. When using coding to determine if there is a match in the pattern, you would use the RegularExpression namespace. This will allow for easy parsing and matching of strings to a specific patter (miscrosoft.com, 2011). Regex myRegEx = new Regex("exam"); string s1 = "There exists just a single example.";

if (myRegEx.IsMatch(s1)) Console.WriteLine("Match found!");

Explain how you could 'teach' a computer to match the word 'exam' in the given phrase above. In order to do this in C#, you could write 4 separate search commands, or you can be more efficient and you can do it in a single phrase. By using pattern = ‘e ?x ?a ?m?’; . now you can locate one or more of the strings with just a single command: Text = [‘There exists just a single example’]; Regexp (text, pattern, ‘match’) Ans = ‘exam’. This is just one of many ways that you could teach a computer to find the word exam in the phrase. You are also able to use different MATLAB returns (MathWorks.com, 2011). Boyer-Moore pattern matching algorithm The algorithm works by creating a “skip table” to each possible character. By using this skip table, the number of actual comparisons needed to locate a string can decrease, and in some cases dramatically (Wood, J.). Comparison is done from right to left, starting with the last character in the patter. So with our search pattern being ‘exam’, we would algorithm would be done as such: There exists just a single example. Exam There exists just a single example Exam There exists just a single example Exam There exists just a single example Exam There exists just a single example Exam There exists just a single example Exam There exists just a single example Exam What methods exist in the string class to do pattern matching There are several methods that exist in pattern matching. There is match(regular expression), replace( regular expression, replacement text ), split (string literal or regular expression ) and search(regular expression). What are regular expressions Regular expressions are special characters that match or capture portions of a field, as well as the rules that govern all characters (Google.com). Those would be these listed below, Wildcards Anchors Grouping Other Regular Expression to Validate Any Email Address using System; using System.Collections.Generic; using System.Text; using System.Text.RegularExpressions;

namespace Dobro.Text.RegularExpressions
{
/// <summary> /// Example of use of TestEmail class, that validates an E-Mail address. /// </summary> class EmailValidator { static void Main(string[] args) { // init string checkOutput = default(string); // default Email-value string[] emails = new string[] { "ab@206.216.255.255", "ab@206.199.255.255","ab.cc.15@dom1.test.com", "max@120.350.200.15", "max@120.250.200.15" }; // Get Email-value from the arguments array if any if (args.Length > 0) { emails = args; }

// check the all given e-mail strings foreach (string email in emails) { // valiadate e-mail address if (TestEmail.IsEmail(email)) { checkOutput = "valid :)"; } else { checkOutput = "invalid :("; }

// show validation result Console.WriteLine( String.Format("\nThe E-Mail address \"{0}\" is {1}", email, checkOutput)); }

// finally Wait4User2Exit(); }

private static void Wait4User2Exit() { Console.WriteLine("\nPress any key to exit ..."); Console.ReadKey(); } }
}

References:
AIU Online. (2011). ITCO321: Unit 5reliable Output [Multimedia Presentation]. Retrieved from AIU Online Virtual Campus. Data Structures and Implementation ITCO321-1103A-02.
Google.com (2011). What are Regular Expressions. Retrieved August 21, 2011 from http://www.google.com/support/analytics/bin/answer.py?answer=55582
Microsoft.com (2011). How to Search Strings using Regular Expressions. Retrieved August 21, 2011 from http://msdn.microsoft.com/en-us/library/ms228595(v=vs.80).aspx
McMillan, M. (2007). Data Structures and Algorithms Using C#. Cambridge University Press.
Wood, J. (2011). Blackbeltcoder.com Fast Text Search with Boyer-Moore. Retrieved August 21, 2011 from http://www.blackbeltcoder.com/Articles/algorithms/fast-text-search-with-boyer-moore