System.Text.RegularExpressions

Regex r = new Regex(@"Windows\s(\w+)(?:\s([\w\s]+))?");

foreach (var input in new[] {
  "Windows Vista Ultimate Edition",
  "Windows XP Professional",
  "Windows 95",
  "Windows 98 Second Edition",
}) {
  Match m = r.Match(input);

  Console.WriteLine("{0} => Release: {1}, Edition: {2}", input, m.Groups[1].Value, m.Groups[2].Value);
}
 Release: {1}, Edition: {2}", input, m.Groups[1].Value, m.Groups[2].Value);
}]]>

Regex r = new Regex(@"Windows\s(?<release>\w+)(?:\s(?<edition>[\w\s]+))?");

foreach (var input in new[] {
  "Windows Vista Ultimate Edition",
  "Windows XP Professional",
  "Windows 95",
  "Windows 98 Second Edition",
}) {
  Match m = r.Match(input);

  Console.WriteLine("{0} => Release: {1}, Edition: {2}", input, m.Groups["release"].Value, m.Groups["edition"].Value);
}
\w+)(?:\s(?[\w\s]+))?");

foreach (var input in new[] {
  "Windows Vista Ultimate Edition",
  "Windows XP Professional",
  "Windows 95",
  "Windows 98 Second Edition",
}) {
  Match m = r.Match(input);

  Console.WriteLine("{0} => Release: {1}, Edition: {2}", input, m.Groups["release"].Value, m.Groups["edition"].Value);
}]]>

Regex r = new Regex(@"Windows\s(\w+)(?:\s([\w\s]+))?");

foreach (var input in new[] {
  "Windows Vista Ultimate Edition",
  "Windows XP Professional",
  "Windows 95",
  "Windows 98 Second Edition",
}) {
  Console.WriteLine("{0} => {1}", input, r.Replace(input, "Release: $1, Edition: $2"));
}
 {1}", input, r.Replace(input, "Release: $1, Edition: $2"));
}]]>

Regex r = new Regex(@"Windows\s(?<release>\w+)(?:\s(?<edition>[\w\s]+))?");

foreach (var input in new[] {
  "Windows Vista Ultimate Edition",
  "Windows XP Professional",
  "Windows 95",
  "Windows 98 Second Edition",
}) {
  Console.WriteLine("{0} => {1}", input, r.Replace(input, "Release: ${release}, Edition: ${edition}"));
}
\w+)(?:\s(?[\w\s]+))?");

foreach (var input in new[] {
  "Windows Vista Ultimate Edition",
  "Windows XP Professional",
  "Windows 95",
  "Windows 98 Second Edition",
}) {
  Console.WriteLine("{0} => {1}", input, r.Replace(input, "Release: ${release}, Edition: ${edition}"));
}]]>

Regex r = new Regex(@"Windows\s(?<release>\w+)(?:\s(?<edition>[\w\s]+))?");

foreach (var input in new[] {
  "Windows Vista Ultimate Edition",
  "Windows XP Professional",
  "Windows 95",
  "Windows 98 Second Edition",
}) {
  Console.WriteLine("{0} => {1}", input, r.Replace(input, "Release: $1, Edition: $2"));
}
\w+)(?:\s(?[\w\s]+))?");

foreach (var input in new[] {
  "Windows Vista Ultimate Edition",
  "Windows XP Professional",
  "Windows 95",
  "Windows 98 Second Edition",
}) {
  Console.WriteLine("{0} => {1}", input, r.Replace(input, "Release: $1, Edition: $2"));
}]]>

var name = new AssemblyName("MyRegexAssembly");
var ns = "MyRegexNamespace";
var regexes = new[] {
  new RegexCompilationInfo(@"\.html$", RegexOptions.IgnoreCase, "HtmlFileRegex", ns, true),
  new RegexCompilationInfo(@"\.xhtml$", RegexOptions.IgnoreCase, "XhtmlFileRegex", ns, true),
  new RegexCompilationInfo(@"\.txt$", RegexOptions.IgnoreCase, "PlainTextFileRegex", ns, true),
};

name.CodeBase = name.Name + ".dll";

Regex.CompileToAssembly(regexes, name);

var htmlFileRegexHandle = Activator.CreateInstanceFrom("MyRegexAssembly.dll", "MyRegexNamespace.HtmlFileRegex");
var htmlFileRegex = (Regex)htmlFileRegexHandle.Unwrap();

htmlFileRegex.IsMatch("index.html");

var inputs = new[] {
  "readme.txt",
  "index.html",
  "index.html.org",
  "INDEX.HTML",
  "index.xhtml",
};
var html = @"\.(?i:html)$";

foreach (var input in inputs) {
  if (Regex.IsMatch(input, html))
    Console.WriteLine("    HTML file : {0}", input);
  else
    Console.WriteLine("not HTML file : {0}", input);
}

var input = "The quick brown fox jumps over the lazy dog";
var word = @"\b\w{3}\b";

for (var m = Regex.Match(input, word); m.Success; m = m.NextMatch()) {
  Console.WriteLine("{0}<{1}>{2}", input.Substring(0, m.Index), m.Value, input.Substring(m.Index + m.Length));
}
{2}", input.Substring(0, m.Index), m.Value, input.Substring(m.Index + m.Length));
}]]>

var input = "The quick brown fox jumps over the lazy dog";
var word = @"\b\w{3}\b";

for (var m = Regex.Match(input, word); m.Success; m = m.NextMatch()) {
  Console.WriteLine(m.Result("$`<$0>$'"));
}
$'"));
}]]>

var input = "The quick brown fox jumps over the lazy dog";
var word = @"\b\w{3}\b";

foreach (Match m in Regex.Matches(input, word)) {
  Console.WriteLine(m.Result("$`<$0>$'"));
}
$'"));
}]]>

var inputs = new[] {
  "column1,,column3",
  "column1,column2,column3,,",
  "\"column1\",\"column\"\"2\"\"\",column3",
};

var quoted = "\"(?<value>(\"\"|\\w)*?)\"";
var plain = "(?<value>\\w*)";
var field = string.Format("({0}|{1})", quoted, plain);
var record = string.Format("^{0}(,{0})*$", field);

foreach (var input in inputs) {
  Console.WriteLine(input);
  foreach (Match m in Regex.Matches(input, record)) {
    foreach (Capture c in m.Groups["value"].Captures) {
      Console.WriteLine("  {0}", c.Value);
    }
  }
}
(\"\"|\\w)*?)\"";
var plain = "(?\\w*)";
var field = string.Format("({0}|{1})", quoted, plain);
var record = string.Format("^{0}(,{0})*$", field);

foreach (var input in inputs) {
  Console.WriteLine(input);
  foreach (Match m in Regex.Matches(input, record)) {
    foreach (Capture c in m.Groups["value"].Captures) {
      Console.WriteLine("  {0}", c.Value);
    }
  }
}]]>

var input = "The quick brown fox jumps over the lazy dog";
var word = @"(?<initial>\w)(?<trail>\w*)";

Console.WriteLine(input);
Console.WriteLine(Regex.Replace(input, word, delegate(Match m) {
  return m.Groups["initial"].Value.ToUpper() + m.Groups["trail"].Value;
}));
\w)(?\w*)";

Console.WriteLine(input);
Console.WriteLine(Regex.Replace(input, word, delegate(Match m) {
  return m.Groups["initial"].Value.ToUpper() + m.Groups["trail"].Value;
}));]]>

var input = "The quick brown fox jumps over the lazy dog";
var initial = @"\b(?<initial>\w)";

Console.WriteLine(input);
Console.WriteLine(Regex.Replace(input, initial, delegate(Match m) {
  return m.Groups["initial"].Value.ToUpper();
}));
\w)";

Console.WriteLine(input);
Console.WriteLine(Regex.Replace(input, initial, delegate(Match m) {
  return m.Groups["initial"].Value.ToUpper();
}));]]>

var input = "The quick brown fox jumps over the lazy dog";
var initial = @"\b\w";

Console.WriteLine(input);
Console.WriteLine(Regex.Replace(input, initial, delegate(Match m) {
  return m.Value.ToUpper();
}));

var input = "line1\r\nline2\nline3\rline4\n\rline6";
var newline = @"\r\n|\r|\n";

foreach (var line in Regex.Split(input, newline)) {
  Console.WriteLine("[{0}]", line);
}

var input = "line1\r\nline2\nline3\rline4\n\rline6";
var newline = @"(\r\n|\r|\n)";

foreach (var line in Regex.Split(input, newline)) {
  Console.WriteLine("[{0}]", line.Replace("\n", "\\n").Replace("\r", "\\r"));
}