Using Regular Expressions with C#

using System;
using System.Text.RegularExpressions;
using System.Collections.Specialized;
class Program {
static void Main()    {
string s1 = @"apple:green:3 banana:yellow:5";
var myRegex = new Regex(@"(\w+):(\w+):(\d+)");

///////// The six main tasks we're likely to have ////////

// Task 1: Is there a match?
Console.WriteLine("*** Is there a Match? ***");
if (myRegex.IsMatch(s1)) Console.WriteLine("Yes");
else Console.WriteLine("No");

// Task 2: How many matches are there?
MatchCollection AllMatches = myRegex.Matches(s1);
Console.WriteLine("\n" + "*** Number of Matches ***");
Console.WriteLine(AllMatches.Count);

// Task 3: What is the first match?
Console.WriteLine("\n" + "*** First Match ***");
Match OneMatch = myRegex.Match(s1);
if (OneMatch.Success)    {
    Console.WriteLine("Overall Match: "+ OneMatch.Groups[0].Value);
    Console.WriteLine("Group 1: " + OneMatch.Groups[1].Value);
    Console.WriteLine("Group 2: " + OneMatch.Groups[2].Value);
    Console.WriteLine("Group 3: " + OneMatch.Groups[3].Value);
    }

// Task 4: What are all the matches?
Console.WriteLine("\n" + "*** Matches ***");
if (AllMatches.Count > 0)    {
    foreach (Match SomeMatch in AllMatches)    {
        Console.WriteLine("Overall Match: " + SomeMatch.Groups[0].Value);
        Console.WriteLine("Group 1: " + SomeMatch.Groups[1].Value);
        Console.WriteLine("Group 2: " + SomeMatch.Groups[2].Value);
        Console.WriteLine("Group 3: " + SomeMatch.Groups[3].Value);
    }
}

// Task 5: Replace the matches
// simple replacement: reverse groups
string replaced = myRegex.Replace(s1, 
       delegate(Match m) {
       return m.Groups[3].Value + ":" +
              m.Groups[2].Value + ":" +
              m.Groups[1].Value;
        }
        );
Console.WriteLine("\n" + "*** Replacements ***");
Console.WriteLine(replaced);

// Task 6: Split
// Let's split at colons or spaces
string[] splits = Regex.Split(s1, @":|\s");
Console.WriteLine("\n" + "*** Splits ***");
foreach (string split in splits) Console.WriteLine(split);

Console.WriteLine("\nPress Any Key to Exit.");
Console.ReadKey();

} // END Main
} // END Program

using System;
using System.Text.RegularExpressions;
class Program {
static void Main() {
string ourString = @"Italian:one=uno,two=due Japanese:one=ichi,two=ni,three=san";
string ourPattern = @"\w+:(?:(\w+)=(\w+),?)+";
var ourRegex = new Regex(ourPattern);
MatchCollection AllMatches = ourRegex.Matches(ourString);

Console.WriteLine("**** Understanding .NET Capture Groups with Quantifiers ****");
Console.WriteLine("\nOur string today is:" + ourString);
Console.WriteLine("Our regex today is:" + ourPattern);
Console.WriteLine("Number of Matches: " + AllMatches.Count);

Console.WriteLine("\n*** Let's Iterate Through the Matches ***");
int matchNum = 1;
foreach (Match SomeMatch in AllMatches)    {
    Console.WriteLine("Match number: " + matchNum++);
    Console.WriteLine("Overall Match: " + SomeMatch.Value);
    Console.WriteLine("\nNumber of Groups: " + SomeMatch.Groups.Count);
    Console.WriteLine("Why three Groups, not two? Because the overall match is Group 0");
    // Another way of printing the overall match
    Console.WriteLine("Group 0: " + SomeMatch.Groups[0].Value);
    Console.WriteLine("Since Groups 1 and 2 have quantifiers, the value of Group 1 and Group 2 is the last capture of each group");
    Console.WriteLine("Group 1: " + SomeMatch.Groups[1].Value);
    Console.WriteLine("Group 2: " + SomeMatch.Groups[2].Value);
    // For this match, let's look all the Group 1 captures manually
    int g1capCount = SomeMatch.Groups[1].Captures.Count;
    Console.WriteLine("Number of Group 1 Captures: " + g1capCount);
    Console.WriteLine("Group 1 Capture 0: " + SomeMatch.Groups[1].Captures[0].Value);
    Console.WriteLine("Group 1 Capture 1: " + SomeMatch.Groups[1].Captures[1].Value);
    // To be safe, we'll check if we have a third capture for Group 1
    // Because the first overall match only has two captures
    if(g1capCount>2) Console.WriteLine("Group 1 Capture 2: " + SomeMatch.Groups[1].Captures[2].Value);
    // Let's look at Group 2 captures automatically
    int g2capCount = SomeMatch.Groups[2].Captures.Count;
    Console.WriteLine("Number of Group 2 Captures: " + g2capCount);
    int i2 = 0;
    foreach (Capture g2capture in SomeMatch.Groups[2].Captures ) {
        Console.WriteLine("Group 2 Capture " + i2 + ": " + g2capture.Value);
        i2++;
        } // end iterate G2 captures
    Console.WriteLine("\n");
    } // end iterate matches

Console.WriteLine("\nPress Any Key to Exit.");
Console.ReadKey();

} // END Main
} // END Program

using System;
using System.Text.RegularExpressions;
class Program {
static void Main()    {
string ourString = @"one:uno dos:two three:tres";
string ourPattern = @"(?<someword>\w+):(?<someword>\w+)";
var ourRegex = new Regex(ourPattern);
MatchCollection AllMatches = ourRegex.Matches(ourString);

Console.WriteLine("**** Understanding Named Capture Reuse ****");
Console.WriteLine("\nOur string today is:" + ourString);
Console.WriteLine("Our regex today is:" + ourPattern);
Console.WriteLine("Number of Matches: " + AllMatches.Count);

Console.WriteLine("\n*** Let's Iterate Through the Matches ***");
int matchNum = 1;
foreach (Match SomeMatch in AllMatches)    {
    Console.WriteLine("Match number: " + matchNum++);
    Console.WriteLine("Overall Match: " + SomeMatch.Value);
    Console.WriteLine("\nNumber of Groups: " + SomeMatch.Groups.Count);
    Console.WriteLine("Why two Groups, not one? Because the overall match is Group 0");
    // Another way of printing the overall match
    Console.WriteLine("Groups[0].Value = " + SomeMatch.Groups[0].Value);
    Console.WriteLine(@"Since the 'someword' group appears more than once in the pattern, the value of Groups[1] and Groups[""someword""] is the last capture of each group");
    Console.WriteLine("Groups[1].Value = " + SomeMatch.Groups[1].Value);
    Console.WriteLine(@"Groups[""someword""].Value = " + SomeMatch.Groups["someword"].Value);
    // Let's look all the first captures manually
    Console.WriteLine("Someword Capture 0: " + SomeMatch.Groups["someword"].Captures[0].Value);

// Let's look at someword captures automatically
    int somewordCapCount = SomeMatch.Groups["someword"].Captures.Count;
    Console.WriteLine("Number of someword Captures: " + somewordCapCount);
    int i2 = 0;
    foreach (Capture someword in SomeMatch.Groups["someword"].Captures)    {
        Console.WriteLine("someword Capture " + i2 + ": " + someword.Value);
    i2++;
    } // end iterate G2 captures
    Console.WriteLine("\n");
} // end iterate matches

Console.WriteLine("\nPress Any Key to Exit.");
Console.ReadKey();

} // END Main
} // END Program

using System;
using System.Text.RegularExpressions;
class Program {
static void Main()    {
string ourString = @"one-two-three:uno-dos-tres one-two-three:ichi-ni-san";
string ourPattern = @"(?:(?<someword>\w+)-?)+:(?:(?<someword>\w+)-?)+";
var ourRegex = new Regex(ourPattern);
MatchCollection AllMatches = ourRegex.Matches(ourString);

Console.WriteLine("**** Understanding Named Capture Reuse ****");
Console.WriteLine("\nOur string today is:" + ourString);
Console.WriteLine("Our regex today is:" + ourPattern);
Console.WriteLine("Number of Matches: " + AllMatches.Count);

Console.WriteLine("\n*** Let's Iterate Through the Matches ***");
int matchNum = 1;
foreach (Match SomeMatch in AllMatches)    {
    Console.WriteLine("Match number: " + matchNum++);
    Console.WriteLine("Overall Match: " + SomeMatch.Value);
    Console.WriteLine("\nNumber of Groups: " + SomeMatch.Groups.Count);
    Console.WriteLine("Why two Groups, not one? Because the overall match is Group 0");
    // Another way of printing the overall match
    Console.WriteLine("Groups[0].Value = " + SomeMatch.Groups[0].Value);
    Console.WriteLine(@"Since the 'someword' group appears more than once in the pattern, the value of Groups[1] and Groups[""someword""] is the last capture of each group");
    Console.WriteLine("Groups[1].Value = " + SomeMatch.Groups[1].Value);
    Console.WriteLine(@"Groups[""someword""].Value = " + SomeMatch.Groups["someword"].Value);
    // Let's look all the first captures manually
    Console.WriteLine("Someword Capture 0: " + SomeMatch.Groups["someword"].Captures[0].Value);

// Let's look at someword captures automatically
    int somewordCapCount = SomeMatch.Groups["someword"].Captures.Count;
    Console.WriteLine("Number of someword Captures: " + somewordCapCount);
    int i2 = 0;
    foreach (Capture someword in SomeMatch.Groups["someword"].Captures)    {
        Console.WriteLine("someword Capture " + i2 + ": " + someword.Value);
    i2++;
    } // end iterate G2 captures
    Console.WriteLine("\n");
} // end iterate matches

Console.WriteLine("\nPress Any Key to Exit.");
Console.ReadKey();

} // END Main
} // END Program