MatchCollection
Class
Definition
Represents the set of successful matches found by iteratively applying a regular expression pattern to the input string.
public class MatchCollection : System.Collections.ICollection
- Inheritance
-
MatchCollection
- Implements
Inherited Members
System.Object
Examples
The following example illustrates the use of the MatchCollection class to interrogate a set of Match instances.
#using <System.dll>
using namespace System;
using namespace System::Text::RegularExpressions;
int main()
{
// Define a regular expression for repeated words.
Regex^ rx = gcnew Regex( "\\b(?<word>\\w+)\\s+(\\k<word>)\\b",static_cast<RegexOptions>(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.", matches->Count );
// Report on each match.
for each (Match^ match in matches)
{
String^ word = match->Groups["word"]->Value;
int index = match->Index;
Console::WriteLine("{0} repeated at position {1}", word, index);
}
}
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
Imports System
Imports System.Text.RegularExpressions
Public Module Test
Public Sub Main()
' Define a regular expression for repeated words.
Dim rx As New Regex("\b(?<word>\w+)\s+(\k<word>)\b", _
RegexOptions.Compiled Or RegexOptions.IgnoreCase)
' Define a test string.
Dim text As String = "The the quick brown fox fox jumped over the lazy dog dog."
' Find matches.
Dim matches As MatchCollection = rx.Matches(text)
' Report the number of matches found.
Console.WriteLine("{0} matches found in:", matches.Count)
Console.WriteLine(" {0}", text)
' Report on each match.
For Each match As Match In matches
Dim groups As GroupCollection = match.Groups
Console.WriteLine("'{0}' repeated at positions {1} and {2}", _
groups.Item("word").Value, _
groups.Item(0).Index, _
groups.Item(1).Index)
Next
End Sub
End Module
' 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
Remarks
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 Match objects. If the match is successful, the collection is populated with one Match object for each match found in the input string. If the match is unsuccessful, the collection contains no 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
foreachstatement (in C#) or theFor Each...Nextstatement (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 Each…Next in Visual Basic) instead of retrieving the enumerator that is returned by the GetEnumerator method.
Properties
| Count |
Gets the number of matches. |
| IsReadOnly |
Gets a value that indicates whether the collection is read only. |
| IsSynchronized |
Gets a value indicating whether access to the collection is synchronized (thread-safe). |
| Item[Int32] |
Gets an individual member of the collection. |
| SyncRoot |
Gets an object that can be used to synchronize access to the collection. |
Methods
| CopyTo(Array, Int32) |
Copies all the elements of the collection to the given array starting at the given index. |
| CopyTo(Match[], Int32) | |
| GetEnumerator() |
Provides an enumerator that iterates through the collection. |
Explicit Interface Implementations
Extension Methods
| Cast<TResult>(IEnumerable) | |
| OfType<TResult>(IEnumerable) | |
| AsParallel(IEnumerable) | |
| AsQueryable(IEnumerable) |