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Match Class

Updated: June 2011

Represents the results from a single regular expression match.

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

[SerializableAttribute]
public class Match : Group

An instance of the Match class is returned by the Regex.Match method and represents the first pattern match in a string. Subsequent matches are represented by Match objects returned by the Match.NextMatch method. In addition, a MatchCollection object that consists of zero, one, or more Match objects is returned by the Regex.Matches method.

If the Regex.Matches method fails to match a regular expression pattern in an input string, it returns an empty MatchCollection object. You can then use a foreach construct in C# or a For Each construct in Visual Basic to iterate the collection.

If the Regex.Match method fails to match the regular expression pattern, it returns a Match object that is equal to Match.Empty. You can use the Success property to determine whether the match was successful. The following example provides an illustration.

// Search for a pattern that is not found in the input string.
string pattern = "dog";
string input = "The cat saw the other cats playing in the back yard.";
Match match = Regex.Match(input, pattern);
if (match.Success )
   // Report position as a one-based integer.
   Console.WriteLine("'{0}' was found at position {1} in '{2}'.", 
                     match.Value, match.Index + 1, input);
else
   Console.WriteLine("The pattern '{0}' was not found in '{1}'.",
                     pattern, input);

If a pattern match is successful, the Value property contains the matched substring, the Index property indicates the zero-based starting position of the matched substring in the input string, and the Length property indicates the length of matched substring in the input string.

Because a single match can involve multiple capturing groups, Match has a Groups property that returns the GroupCollection. The GroupCollection has accessors that return each group. The Match instance itself is equivalent to the first object in the collection, at Match.Groups[0] (Match.Groups(0) in Visual Basic), which represents the entire match.

The following examples use the regular expression Console\.Write(Line)?. The regular expression is interpreted as follows:

Console\.Write

Match the string "Console.Write". Note that the "." character is escaped so that it is interpreted as a literal period rather than as a wildcard that matches any character.

(Line)?

Match zero or one occurrence of the string "Line".

Example 1

The following example calls the Regex.Matches(String, String) method to retrieve all pattern matches in an input string. It then iterates the Match objects in the returned MatchCollection object to display information about each match.

using System;
using System.Text.RegularExpressions;

public class Example
{
   public static void Main()
   {
      string input = "int[] values = { 1, 2, 3 };\n" +
                     "for (int ctr = values.GetLowerBound(1); ctr <= values.GetUpperBound(1); ctr++)\n" +
                     "{\n" +
                     "   Console.Write(values[ctr]);\n" +
                     "   if (ctr < values.GetUpperBound(1))\n" +
                     "      Console.Write(\", \");\n" +
                     "}\n" +
                     "Console.WriteLine();\n";   

      string pattern = @"Console\.Write(Line)?";
      MatchCollection matches = Regex.Matches(input, pattern);
      foreach (Match match in matches)
         Console.WriteLine("'{0}' found in the source code at position {1}.",  
                           match.Value, match.Index);
   }
}
// The example displays the following output: 
//    'Console.Write' found in the source code at position 115. 
//    'Console.Write' found in the source code at position 184. 
//    'Console.WriteLine' found in the source code at position 211.

Example 2

The following example calls the Match(String, String) and NextMatch methods to retrieve one match at a time.

using System;
using System.Text.RegularExpressions;

public class Example
{
   public static void Main()
   {
      string input = "int[] values = { 1, 2, 3 };\n" +
                     "for (int ctr = values.GetLowerBound(1); ctr <= values.GetUpperBound(1); ctr++)\n" +
                     "{\n" +
                     "   Console.Write(values[ctr]);\n" +
                     "   if (ctr < values.GetUpperBound(1))\n" +
                     "      Console.Write(\", \");\n" +
                     "}\n" +
                     "Console.WriteLine();\n";   
      string pattern = @"Console\.Write(Line)?";
      Match match = Regex.Match(input, pattern);
      while (match.Success)
      {
         Console.WriteLine("'{0}' found in the source code at position {1}.",  
                           match.Value, match.Index);
         match = match.NextMatch();
      }
   }
}
// The example displays the following output: 
//    'Console.Write' found in the source code at position 115. 
//    'Console.Write' found in the source code at position 184. 
//    'Console.WriteLine' found in the source code at position 211.

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

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

June 2011

Revised the comments about the GroupCollection object and modified the regular expression pattern in the example.

Customer feedback.

February 2009

Expanded the Remarks section and added an example.

Customer feedback.

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