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Regex.Matches Method (String, Int32)

Updated: September 2010

Searches the specified input string for all occurrences of a regular expression, beginning at the specified starting position in the string.

Namespace:  System.Text.RegularExpressions
Assembly:  System (in System.dll)

public MatchCollection Matches(
	string input,
	int startat
)

Parameters

input
Type: System.String

The string to search for a match.

startat
Type: System.Int32

The character position in the input string at which to start the search.

Return Value

Type: System.Text.RegularExpressions.MatchCollection
A collection of the Match objects found by the search. If no matches are found, the method returns an empty collection object.

ExceptionCondition
ArgumentNullException

input is null.

ArgumentOutOfRangeException

startat is less than zero or greater than the length of input.

The Matches method is similar to the Match method, except that it returns information about all the matches, instead of a single match, found in the input string. It is equivalent to the following code:

Match match = regex.Match(input, startAt);
while (match.Success) {
      // Handle match here...

      match = match.NextMatch();
}  

The collection includes only successful matches and terminates at the first unsuccessful match.

The regular expression pattern for which the Regex.Matches(String, Int32) method searches is defined by the call to one of the Regex class constructors. For more information about the elements that can form a regular expression pattern, see Regular Expression Language - Quick Reference.

The Matches method uses lazy evaluation to populate the returned MatchCollection object. Accessing such members of this collection as MatchCollection.Count and MatchCollection.CopyTo causes the collection to be populated immediately. To take advantage of lazy evaluation, you should iterate the collection by using a construct such as foreach in C# and For EachNext in Visual Basic.

The following example uses the Match(String) method to find the first word in a sentence that ends in "es", and then calls the Matches(String, Int32) method to identify any additional words that end in "es".

using System;
using System.Text.RegularExpressions;

public class Example
{
   public static void Main()
   {
      string pattern = @"\b\w+es\b";
      Regex rgx = new Regex(pattern);
      string sentence = "Who writes these notes and uses our paper?";

      // Get the first match.
      Match match = rgx.Match(sentence);
      if (match.Success) {
         Console.WriteLine("Found first 'es' in '{0}' at position {1}", 
                           match.Value, match.Index);
         // Get any additional matches. 
         foreach (Match m in rgx.Matches(sentence, match.Index + match.Length))
            Console.WriteLine("Also found '{0}' at position {1}", 
                              m.Value, m.Index);
      }   
   }
}
// The example displays the following output: 
//       Found first 'es' in 'writes' at position 4 
//       Also found 'notes' at position 17 
//       Also found 'uses' at position 27

The regular expression pattern \b\w+es\b is defined as shown in the following table.

Pattern

Description

\b

Begin the match at a word boundary.

\w+

Match one or more word characters.

es

Match the literal string "es".

\b

End the match at a word boundary.

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC, Xbox 360, Zune

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5, 3.0, 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 3.5, 2.0, 1.0

XNA Framework

Supported in: 3.0, 2.0, 1.0

Date

History

Reason

September 2010

Expanded the Return Value and Remarks sections.

Customer feedback.

February 2010

Added an example.

Customer feedback.

July 2009

Included additional exception information.

Content bug fix.

March 2009

Expanded the Remarks section.

Customer feedback.

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