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 = @"<ashrefS*/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");
    }
}

    

   


using System;
using System.Text.RegularExpressions;

class RegexMatches
{
   public static void Main()
   {
      Regex expression = new Regex( @"J.*d[0-35-9]-dd-dd" );

      string string1 = "Jane's Birthday is 05-12-75
" +
         "Jave's Birthday is 11-04-78
" +
         "John's Birthday is 04-28-73
" +
         "Joe's Birthday is 12-17-77";

      foreach ( Match myMatch in expression.Matches( string1 ) )
         Console.WriteLine( myMatch );
   }
}

           
          

   


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");
      }   
   }
}

           
          

   


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");
      }   
   }
}

           
          

   


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");
      } 
   }
}

           
          

   

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");
      } 
   }
}


           
          

   

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");
      }

   }
}