Csharp/C Sharp/Development Class/Regular Expression

((an)|(in)|(on))

 
using System;
using System.Text.RegularExpressions;
public class MainClass {
    public static void Main() {
        Regex p = new Regex("((an)|(in)|(on))");
        MatchCollection mn = p.Matches("King, Kong Kang");
        for (int i = 0; i < mn.Count; i++) {
            Console.WriteLine("Found "{0}" at position {1}",mn[i].Value, mn[i].Index);
        }
    }
}

Define groups "ing", "in", "n"

 

using System;
using System.Text.RegularExpressions;
class GroupingApp {
    static void Main(string[] args) {
        Regex r = new Regex("(i(n))g");
        Match m = r.Match("Matching");
        GroupCollection gc = m.Groups;
        Console.WriteLine("Found {0} Groups", gc.Count);
        for (int i = 0; i < gc.Count; i++) {
            Group g = gc[i];
            Console.WriteLine("Found "{0}" at position {1}",g.Value, g.Index);
        }
    }
}

Gr(a|e)y

 
using System;
using System.Text.RegularExpressions;

public class MainClass {
    public static void Main() {
        Regex n = new Regex("Gr(a|e)y");
        MatchCollection mp = n.Matches("Green, Grey, Granite, Gray");
        for (int i = 0; i < mp.Count; i++) {
            Console.WriteLine("Found "{0}" at position {1}",mp[i].Value, mp[i].Index);
        }
    }
}

HTML Parser

 
using System;
using System.Text.RegularExpressions;
using System.IO;
using System.Text;
public class HTMLParser {
    public static void Main(String[] args) {
        FileInfo MyFile = new FileInfo(args[0].ToString());
        if (MyFile.Exists) {
            StreamReader sr = MyFile.OpenText();
            string text = sr.ReadToEnd();
            sr.Close();
            string pattern = @"<a\shref\S*/a>";
            MatchCollection patternMatches = Regex.Matches(text, pattern,
              RegexOptions.IgnoreCase);
            foreach (Match nextMatch in patternMatches) {
                Console.WriteLine(nextMatch.ToString());
            }
        } else
            Console.WriteLine("The input file does not exist");
    }
}

IP address

 
using System;
using System.Text.RegularExpressions;

class RXassemblyApp {
    static void Main(string[] args) {
        string s = "123.45.67.89";
        string e =
            @"([01]?\d\d?|2[0-4]\d|25[0-5])\." +
            @"([01]?\d\d?|2[0-4]\d|25[0-5])\." +
            @"([01]?\d\d?|2[0-4]\d|25[0-5])\." +
            @"([01]?\d\d?|2[0-4]\d|25[0-5])";
        Match m = Regex.Match(s, e);
        Console.WriteLine("IP Address: {0}", m);
        for (int i = 1; i < m.Groups.Count; i++)
            Console.WriteLine(
                "\tGroup{0}={1}", i, m.Groups[i]);
    }
}

Leading space

 
using System;
using System.Text.RegularExpressions;

class RXmodifyingApp {
    static void Main(string[] args) {
        string s = "     leading";
        string e = @"^\s+";
        Regex rx = new Regex(e);
        string r = rx.Replace(s, "");
        Console.WriteLine("Strip leading space: {0}", r);
    }
}

Multiple different delimiters

 
using System;
using System.Text.RegularExpressions;

public class MainClass {
    public static void Main() {
        string t = "Once,Upon:A/Time\\In\"America";
        Regex q = new Regex(@" |,|:|/|\\|\"");
        foreach (string ss in q.Split(t)) {
            Console.WriteLine(ss);
        }
    }
}

Multiple spaces, using \" \"

 
using System;
using System.Text.RegularExpressions;

public class MainClass {
    public static void Main() {
        string u = "Once   Upon A Time In   America";
        Regex p = new Regex(" ");
        foreach (string ss in p.Split(u)) {
            Console.WriteLine(ss);
        }
    }
}

Multiple spaces, using \"[\\s]+\"

 
using System;
using System.Text.RegularExpressions;

public class MainClass {
    public static void Main() {
        string v = "Once   Upon A Time In   America";
        Regex o = new Regex(@"[\s]+");
        foreach (string ss in o.Split(v)) {
            Console.WriteLine(ss);
        }
    }
}

Position and index

 
using System;
using System.Text.RegularExpressions;

class MatchingApp {
    static void Main(string[] args) {
        Regex r = new Regex("in");
        Match m = r.Match("Matching");
        if (m.Success) {
            Console.WriteLine("Found "{0}" at position {1}",m.Value, m.Index);
        }
    }
}

Proper case match

 
using System;
using System.Text.RegularExpressions;

public class RXProperCaseApp {
    static void Main(string[] args) {
        string s = "the qUEEn wAs in HER parLOr";
        s = s.ToLower();
        string e = @"\w+|\W+";
        string sProper = "";
        foreach (Match m in Regex.Matches(s, e)) {
            sProper += char.ToUpper(m.Value[0])
                + m.Value.Substring(1, m.Length - 1);
        }
        Console.WriteLine("ProperCase:\t{0}", sProper);
    }
}

Regex and letter case

 
using System;
using System.Text.RegularExpressions;

public class MainClass {
    public static void Main() {
        Regex q = new Regex(" in ");
        MatchCollection mm = q.Matches("IN at in or");
        for (int i = 0; i < mm.Count; i++) {
            Console.WriteLine("Found "{0}" at position {1}",mm[i].Value, mm[i].Index);
        }
    }
}

Single space split

 
using System;
using System.Text.RegularExpressions;

public class MainClass {
    public static void Main() {
        string u = "Once   Upon A Time In   America";
        Regex p = new Regex(" ");
        foreach (string ss in p.Split(u)) {
            if (ss.Length > 0)
                Console.WriteLine(ss);
        }
    }
}

Single spaces, using ()

 
using System;
using System.Text.RegularExpressions;

public class MainClass {
    public static void Main() {
        string x = "Once Upon A Time In America";
        Regex m = new Regex("( )");
        foreach (string ss in m.Split(x)) {
            Console.WriteLine(ss);
        }
    }
}

Single spaces, using new Regex("( )")

 
using System;
using System.Text.RegularExpressions;

public class MainClass {
    public static void Main() {
        string x = "Once Upon A Time In America";
        Regex m = new Regex("( )");
        foreach (string ss in m.Split(x)) {
            Console.WriteLine(ss);
        }
    }
}

Use regular expression to replace chars

using System;
using System.Text.RegularExpressions;
class RegexSubstitution
{
   public static void Main()
   {
      string testString1 = " stars *****";
      Regex testRegex1 = new Regex( @"\d" );
      Console.WriteLine( "Original string: " + testString1 );
      testString1 = Regex.Replace( testString1, @"\*", "^" );
      Console.WriteLine( "^ substituted for *: " + testString1 );
      
   }
}

Use regular expression to replace first 3 digits

using System;
using System.Text.RegularExpressions;
class RegexSubstitution
{
   public static void Main()
   {
      string testString1 = "1, 2, 3, 4, 5, 6, 7, 8";
      Regex testRegex1 = new Regex( @"\d" );
      Console.WriteLine( "Original string: " + testString1 );
      Console.WriteLine( "Replace first 3 digits by \"digit\": " + testRegex1.Replace( testString1, "digit", 3 ) );
   }
}

Use regular to replace strings

using System;
using System.Text.RegularExpressions;
class RegexSubstitution
{
   public static void Main()
   {
      string testString1 = " stars *****";
      Regex testRegex1 = new Regex( @"\d" );
      Console.WriteLine( "Original string: " + testString1 );
      testString1 = Regex.Replace( testString1, "stars", "carets" );
      Console.WriteLine( "\"carets\" substituted for \"stars\": " + testString1 );
      
   }
}

Use regular to replace word

using System;
using System.Text.RegularExpressions;
class RegexSubstitution
{
   public static void Main()
   {
      string testString1 = "a b c stars *****";
      Regex testRegex1 = new Regex( @"\d" );
      Console.WriteLine( "Original string: " + testString1 );
      Console.WriteLine( "Every word replaced by \"word\": " + Regex.Replace( testString1, @"\w+", "word" ) );
      
   }
}

Use regular to split string

using System;
using System.Text.RegularExpressions;
class RegexSubstitution
{
   public static void Main()
   {
      string testString1 = "1, 2, 3, 4, 5, 6, 7, 8";
      Regex testRegex1 = new Regex( @"\d" );
      Console.WriteLine( "Original string: " + testString1 );
      String[] result = Regex.Split( testString1, @",\s" );
      foreach ( string resultString in result )
         Console.WriteLine("\"" + resultString + "\", ");
   }
}

Use regular to verify a date

using System;
using System.Text.RegularExpressions;
class RegexMatches
{
   public static void Main()
   {
      Regex expression = new Regex( @"J.*\d[0-35-9]-\d\d-\d\d" );
      string string1 = "Jane"s Birthday is 05-12-75\n" +
         "Jave"s Birthday is 11-04-78\n" +
         "John"s Birthday is 04-28-73\n" +
         "Joe"s Birthday is 12-17-77";
      foreach ( Match myMatch in expression.Matches( string1 ) )
         Console.WriteLine( myMatch );
   }
}

Use | to combine different case

 
using System;
using System.Text.RegularExpressions;

class RXOptionsApp {
    static void Main(string[] args) {
        Regex r = new Regex("in|In|IN|iN");
        string s = "The KING Was In His Counting House";
        MatchCollection mc = r.Matches(s);
        for (int i = 0; i < mc.Count; i++) {
            Console.WriteLine("Found "{0}" at position {1}",mc[i].Value, mc[i].Index);
        }
    }
}

Validate address

using System;
using System.Text.RegularExpressions;
class RegexSubstitution
{
   public static void Main()
   {
      string text = "124 street";
      if ( !Regex.Match( text, @"^[0-9]+\s+([a-zA-Z]+|[a-zA-Z]+\s[a-zA-Z]+)$" ).Success ) {
         Console.WriteLine( "Invalid address");
      } 
   }
}

Validate city name

using System;
using System.Text.RegularExpressions;
class RegexSubstitution
{
   public static void Main()
   {
      string text = "124 street";
      if ( !Regex.Match(text,@"^([a-zA-Z]+|[a-zA-Z]+\s[a-zA-Z]+)$" ).Success )
      {
         Console.WriteLine( "Invalid city");
      } 
   }
}

Validate first name and last name

using System;
using System.Text.RegularExpressions;
class RegexSubstitution
{
   public static void Main()
   {
      string text = "Name";
      if ( !Regex.Match(text,"^[A-Z][a-zA-Z]*$" ).Success )
      {
         Console.WriteLine( "Invalid last name");
      }
   }
}

Validate Phone Number

using System;
using System.Text.RegularExpressions;
class RegexSubstitution
{
   public static void Main()
   {
      string text = "124";
      if ( !Regex.Match(text,@"^[1-9]\d{2}-[1-9]\d{2}-\d{4}$" ).Success )
      {
         Console.WriteLine( "Invalid phone number");
      }   
   }
}

Validate ZIP code

using System;
using System.Text.RegularExpressions;
class RegexSubstitution
{
   public static void Main()
   {
      string text = "124";
      if ( !Regex.Match( text, @"^\d{5}$" ).Success )
      {
         Console.WriteLine( "Invalid zip code");
      }   
   }
}