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Regex.Match Method (String)

Searches the specified input string for the first occurrence of the regular expression specified in the Regex constructor.

Namespace:  System.Text.RegularExpressions
Assembly:  System (in System.dll)
public Match Match(
	string input
)

Parameters

input
Type: System.String

The string to search for a match.

Return Value

Type: System.Text.RegularExpressions.Match
An object that contains information about the match.
ExceptionCondition
ArgumentNullException

input is null.

RegexMatchTimeoutException

A time-out occurred. For more information about time-outs, see the Remarks section.

The Match(String) method returns the first substring that matches a regular expression pattern in an input string. For information about the language elements used to build a regular expression pattern, see Regular Expression Language - Quick Reference.

You can determine whether the regular expression pattern has been found in the input string by checking the value of the returned Match object's Success property. If a match is found, the returned Match object's Value property contains the substring from input that matches the regular expression pattern. If no match is found, its value is String.Empty.

This method returns the first substring in input that matches the regular expression pattern. You can retrieve subsequent matches by repeatedly calling the returned Match object's Match.NextMatch method. You can also retrieve all matches in a single method call by calling the Regex.Matches(String) method.

The RegexMatchTimeoutException exception is thrown if the execution time of the matching operation exceeds the time-out interval specified by the Regex.Regex(String, RegexOptions, TimeSpan) constructor. If you do not set a time-out interval when you call the constructor, the exception is thrown if the operation exceeds any time-out value established for the application domain in which the Regex object is created. If no time-out is defined in the Regex constructor call or in the application domain's properties, or if the time-out value is Regex.InfiniteMatchTimeout, no exception is thrown.

The following example finds regular expression pattern matches in a string, then lists the matched groups, captures, and capture positions.

using System;
using System.Text.RegularExpressions;

class Example 
{
   static void Main() 
   {
      string text = "One car red car blue car";
      string pat = @"(\w+)\s+(car)";

      // Instantiate the regular expression object.
      Regex r = new Regex(pat, RegexOptions.IgnoreCase);

      // Match the regular expression pattern against a text string.
      Match m = r.Match(text);
      int matchCount = 0;
      while (m.Success) 
      {
         Console.WriteLine("Match"+ (++matchCount));
         for (int i = 1; i <= 2; i++) 
         {
            Group g = m.Groups[i];
            Console.WriteLine("Group"+i+"='" + g + "'");
            CaptureCollection cc = g.Captures;
            for (int j = 0; j < cc.Count; j++) 
            {
               Capture c = cc[j];
               System.Console.WriteLine("Capture"+j+"='" + c + "', Position="+c.Index);
            }
         }
         m = m.NextMatch();
      }
   }
}
// This example displays the following output: 
//       Match1 
//       Group1='One' 
//       Capture0='One', Position=0 
//       Group2='car' 
//       Capture0='car', Position=4 
//       Match2 
//       Group1='red' 
//       Capture0='red', Position=8 
//       Group2='car' 
//       Capture0='car', Position=12 
//       Match3 
//       Group1='blue' 
//       Capture0='blue', Position=16 
//       Group2='car' 
//       Capture0='car', Position=21

The regular expression pattern (\w+)\s+(car) matches occurrences of the word "car" along with the word that precedes it. It is interpreted as shown in the following table.

Pattern

Description

(\w+)

Match one or more word characters. This is the first capturing group.

\s+

Match one or more white-space characters.

(car)

Match the literal string "car". This is the second capturing group.

.NET Framework

Supported in: 4.5.1, 4.5, 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

.NET for Windows Store apps

Supported in: Windows 8

.NET for Windows Phone apps

Supported in: Windows Phone 8.1, Windows Phone 8, Silverlight 8.1

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

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

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