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MatchCollection Class

Represents the set of successful matches found by iteratively applying a regular expression pattern to the input string.

System.Object
  System.Text.RegularExpressions.MatchCollection

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

[SerializableAttribute]
public class MatchCollection : ICollection, 
	IEnumerable

The MatchCollection type exposes the following members.

  NameDescription
Public propertySupported by the XNA FrameworkSupported by Portable Class LibraryCountGets the number of matches.
Public propertySupported by the XNA FrameworkIsReadOnlyGets a value that indicates whether the collection is read only.
Public propertySupported by the XNA FrameworkIsSynchronizedGets a value indicating whether access to the collection is synchronized (thread-safe).
Public propertySupported by the XNA FrameworkSupported by Portable Class LibraryItemGets an individual member of the collection.
Public propertySupported by the XNA FrameworkSyncRootGets an object that can be used to synchronize access to the collection.
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  NameDescription
Public methodSupported by the XNA FrameworkCopyToCopies all the elements of the collection to the given array starting at the given index.
Public methodSupported by the XNA FrameworkSupported by Portable Class LibraryEquals(Object)Determines whether the specified Object is equal to the current Object. (Inherited from Object.)
Protected methodSupported by the XNA FrameworkSupported by Portable Class LibraryFinalizeAllows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.)
Public methodSupported by the XNA FrameworkSupported by Portable Class LibraryGetEnumeratorProvides an enumerator that iterates through the collection.
Public methodSupported by the XNA FrameworkSupported by Portable Class LibraryGetHashCodeServes as a hash function for a particular type. (Inherited from Object.)
Public methodSupported by the XNA FrameworkSupported by Portable Class LibraryGetTypeGets the Type of the current instance. (Inherited from Object.)
Protected methodSupported by the XNA FrameworkSupported by Portable Class LibraryMemberwiseCloneCreates a shallow copy of the current Object. (Inherited from Object.)
Public methodSupported by the XNA FrameworkSupported by Portable Class LibraryToStringReturns a string that represents the current object. (Inherited from Object.)
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  NameDescription
Public Extension MethodAsParallelEnables parallelization of a query. (Defined by ParallelEnumerable.)
Public Extension MethodSupported by Portable Class LibraryAsQueryableConverts an IEnumerable to an IQueryable. (Defined by Queryable.)
Public Extension MethodSupported by the XNA FrameworkSupported by Portable Class LibraryCast<TResult>Casts the elements of an IEnumerable to the specified type. (Defined by Enumerable.)
Public Extension MethodSupported by the XNA FrameworkSupported by Portable Class LibraryOfType<TResult>Filters the elements of an IEnumerable based on a specified type. (Defined by Enumerable.)
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  NameDescription
Explicit interface implemetationPrivate methodSupported by Portable Class LibraryICollection.CopyToCopies all the elements of the collection to the specified array starting at the specified index.
Explicit interface implemetationPrivate propertySupported by Portable Class LibraryICollection.IsSynchronizedGets a value that indicates whether access to the collection is synchronized (thread-safe).
Explicit interface implemetationPrivate propertySupported by Portable Class LibraryICollection.SyncRootGets an object that can be used to synchronize access to the collection.
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The collection is immutable (read-only) and has no public constructor. The Regex.Matches method returns a MatchCollection object.

The collection contains zero or more System.Text.RegularExpressions.Match objects. If the match is successful, the collection is populated with one System.Text.RegularExpressions.Match object for each match found in the input string. If the match is unsuccessful, the collection contains no System.Text.RegularExpressions.Match objects, and its Count property equals zero.

When applying a regular expression pattern to a particular input string, the regular expression engine uses either of two techniques to build the MatchCollection object:

  • Direct evaluation.

    The MatchCollection object is populated all at once, with all matches resulting from a particular call to the Regex.Matches method. This technique is used when the collection's Count property is accessed. It typically is the more expensive method of populating the collection and entails a greater performance hit.

  • Lazy evaluation.

    The MatchCollection object is populated as needed on a match-by-match basis. It is equivalent to the regular expression engine calling the Regex.Match method repeatedly and adding each match to the collection. This technique is used when the collection is accessed through its GetEnumerator method, or when it is accessed using the foreach statement (in C#) or the For Each...Next statement (in Visual Basic).

To iterate through the members of the collection, you should use the collection iteration construct provided by your language (such as foreach in C# and For EachNext in Visual Basic) instead of retrieving the enumerator that is returned by the GetEnumerator method.

The following example illustrates the use of the MatchCollection class to interrogate a set of Match instances.


using System;
using System.Text.RegularExpressions;

public class Test
{

    public static void Main ()
    {

        // Define a regular expression for repeated words.
        Regex rx = new Regex(@"\b(?<word>\w+)\s+(\k<word>)\b",
          RegexOptions.Compiled | RegexOptions.IgnoreCase);

        // Define a test string.        
        string text = "The the quick brown fox  fox jumped over the lazy dog dog.";

        // Find matches.
        MatchCollection matches = rx.Matches(text);

        // Report the number of matches found.
        Console.WriteLine("{0} matches found in:\n   {1}", 
                          matches.Count, 
                          text);

        // Report on each match.
        foreach (Match match in matches)
        {
            GroupCollection groups = match.Groups;
            Console.WriteLine("'{0}' repeated at positions {1} and {2}",  
                              groups["word"].Value, 
                              groups[0].Index, 
                              groups[1].Index);
        }

    }
	
}
// The example produces the following output to the console:
//       3 matches found in:
//          The the quick brown fox  fox jumped over the lazy dog dog.
//       'The' repeated at positions 0 and 4
//       'fox' repeated at positions 20 and 25
//       'dog' repeated at positions 50 and 54


.NET Framework

Supported in: 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Portable Class Library

Supported in: Portable Class Library

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

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

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

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