using System;

using System.Collections.Generic;

using System.Globalization;

using System.Text.RegularExpressions;

​

public class Example

{

   public static void Main()

   {

      // Define text to be parsed.

      string input = "Office expenses on 2/13/2008:\n" +

                     "Paper (500 sheets)                      $3.95\n" +

                     "Pencils (box of 10)                     $1.00\n" +

                     "Pens (box of 10)                        $4.49\n" +

                     "Erasers                                 $2.19\n" +

                     "Ink jet printer                        $69.95\n\n" +

                     "Total Expenses                        $ 81.58\n";

​

      // Get current culture's NumberFormatInfo object.

      NumberFormatInfo nfi = CultureInfo.CurrentCulture.NumberFormat;

      // Assign needed property values to variables.

      string currencySymbol = nfi.CurrencySymbol;

      bool symbolPrecedesIfPositive = nfi.CurrencyPositivePattern % 2 == 0;

      string groupSeparator = nfi.CurrencyGroupSeparator;

      string decimalSeparator = nfi.CurrencyDecimalSeparator;

​

      // Form regular expression pattern.

      string pattern = Regex.Escape( symbolPrecedesIfPositive ? currencySymbol : "") +

                       @"\s*[-+]?" + "([0-9]{0,3}(" + groupSeparator + "[0-9]{3})*(" +

                       Regex.Escape(decimalSeparator) + "[0-9]+)?)" +

                       (! symbolPrecedesIfPositive ? currencySymbol : "");

      Console.WriteLine( "The regular expression pattern is:");

      Console.WriteLine("   " + pattern);

​

      // Get text that matches regular expression pattern.

      MatchCollection matches = Regex.Matches(input, pattern,

                                              RegexOptions.IgnorePatternWhitespace);

      Console.WriteLine("Found {0} matches.", matches.Count);

​

      // Get numeric string, convert it to a value, and add it to List object.

      List<decimal> expenses = new List<Decimal>();

​

      foreach (Match match in matches)

         expenses.Add(Decimal.Parse(match.Groups[1].Value));

​

      // Determine whether total is present and if present, whether it is correct.

      decimal total = 0;

      foreach (decimal value in expenses)

         total += value;

​

      if (total / 2 == expenses[expenses.Count - 1])

         Console.WriteLine("The expenses total {0:C2}.", expenses[expenses.Count - 1]);

      else

         Console.WriteLine("The expenses total {0:C2}.", total);

   }

}

// The example displays the following output:

//       The regular expression pattern is:

//          \$\s*[-+]?([0-9]{0,3}(,[0-9]{3})*(\.[0-9]+)?)

//       Found 6 matches.

//       The expenses total $81.58.