MyRegex.cs

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

namespace com.williambryanmiller.regularexpressions {

    class MyRegex {

        public const string MatchEmailPattern =
    @"^[a-zA-Z][\w\.-]*[a-zA-Z0-9]@[a-zA-Z0-9][\w\.-]*[a-zA-Z0-9]\.[a-zA-Z][a-zA-Z\.]*[a-zA-Z]$";

        //matches extraneous whitespace (i.e., 2 or more consecutive spaces but
        //does NOT consider a carriage return or line feed as whitespace
        public const string MatchExtraWhitespace = @"[^\S\r\n]{2,}";

        public const string MatchLonelyPeriods = @"(\s{1,}\.)";

        public const string Match_to_ot_Transposition = @"(\bot\b)";

        public const string MatchPeriodsWithoutTrailingSpace = @"\.(?! |$)";




        public static string fixLonelyPeriods(string p) {
            //find instances of one or more space characters followed by a period,
            //and replace with a period
            return Regex.Replace(p, MatchLonelyPeriods, ".");
        }

        public static string fixPeriodsWithoutTrailingSpace(string p) {
            return Regex.Replace(p, MatchPeriodsWithoutTrailingSpace, ". ");
        }

        public static string fixTransposition(string p, string pattern, string replacement) {
            return Regex.Replace(p, pattern, replacement);
        }

        public static bool isEmail(string sEmail) {
            if (sEmail != null) {
                return Regex.IsMatch(sEmail, MatchEmailPattern);
            } else {
                //if sEmail is null, we don't test at all
                return false;
            }
        }

        public static string removeExtraWhitespace(string p) {
            return Regex.Replace(p, MatchExtraWhitespace, " ");
        }

        public static int numCarriageReturnLineFeeds(string text) {
            Regex RE = new Regex("\r\n", RegexOptions.Multiline);
            MatchCollection matches = RE.Matches(text);
            return matches.Count;;
        }

        public static int numOfMatches(string text, string expr) {
            MatchCollection mc = Regex.Matches(text, expr);
            return mc.Count;
        }

        public static int numWordsEndingIn(string text, string ending){
            MatchCollection mc = Regex.Matches(text, @"\b\S*" + ending + @"\b");
            return mc.Count;
        }


    }
}