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RegexOptions Enumeration

Provides enumerated values to use to set regular expression options.

This enumeration has a FlagsAttribute attribute that allows a bitwise combination of its member values.

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

[FlagsAttribute]
public enum RegexOptions

Member nameDescription
Supported by the .NET Compact FrameworkSupported by the XNA FrameworkNoneSpecifies that no options are set.
Supported by the .NET Compact FrameworkSupported by the XNA FrameworkIgnoreCaseSpecifies case-insensitive matching.
Supported by the .NET Compact FrameworkSupported by the XNA FrameworkMultilineMultiline mode. Changes the meaning of ^ and $ so they match at the beginning and end, respectively, of any line, and not just the beginning and end of the entire string.
Supported by the .NET Compact FrameworkSupported by the XNA FrameworkExplicitCaptureSpecifies that the only valid captures are explicitly named or numbered groups of the form (?<name>…). This allows unnamed parentheses to act as noncapturing groups without the syntactic clumsiness of the expression (?:…).
Supported by the .NET Compact FrameworkSupported by the XNA FrameworkCompiledSpecifies that the regular expression is compiled to an assembly. This yields faster execution but increases startup time. This value should not be assigned to the Options property when calling the CompileToAssembly method.
Supported by the .NET Compact FrameworkSupported by the XNA FrameworkSinglelineSpecifies single-line mode. Changes the meaning of the dot (.) so it matches every character (instead of every character except \n).
Supported by the .NET Compact FrameworkSupported by the XNA FrameworkIgnorePatternWhitespaceEliminates unescaped white space from the pattern and enables comments marked with #. However, the IgnorePatternWhitespace value does not affect or eliminate white space in character classes.
Supported by the .NET Compact FrameworkSupported by the XNA FrameworkRightToLeftSpecifies that the search will be from right to left instead of from left to right.
Supported by the .NET Compact FrameworkSupported by the XNA FrameworkECMAScriptEnables ECMAScript-compliant behavior for the expression. This value can be used only in conjunction with the IgnoreCase, Multiline, and Compiled values. The use of this value with any other values results in an exception.
Supported by the .NET Compact FrameworkSupported by the XNA FrameworkCultureInvariantSpecifies that cultural differences in language is ignored. See Performing Culture-Insensitive Operations in the RegularExpressions Namespace for more information.

A RegexOptions value can be provided as a parameter to the following members of the Regex class:

A RegexOptions value can also be supplied as a parameter to the RegexCompilationInfo constructor, or it can be assigned directly to the Options property. The resulting RegexCompilationInfo object is then used in the call to the CompileToAssembly method.

Several options provided by members of the RegexOptions enumeration (in particular, by its RegexOptions.ExplicitCapture, RegexOptions.IgnoreCase, RegexOptions.Multiline, and RegexOptions.Singleline members) can instead be provided by using an inline option character in the regular expression pattern. For details, see Regular Expression Options.

The following example defines two regular expressions that identify repeated words in text but that are instantiated using different RegexOptions values. The first regular expression is case-insensitive; case is ignored when determining whether a word is identical to the preceding word. The second regular expression is case-sensitive; a word must match the case of the preceding word exactly to be considered a duplicate.

using System;
using System.Text.RegularExpressions;

public class Test
{
    public static void Main ()
    {
        // Define a case-insensitive regular expression for repeated words.
        Regex rxInsensitive = new Regex(@"\b(?<word>\w+)\s+(\k<word>)\b",
          RegexOptions.Compiled | RegexOptions.IgnoreCase);
        // Define a case-sensitive regular expression for repeated words.
        Regex rxSensitive = new Regex(@"\b(?<word>\w+)\s+(\k<word>)\b",
          RegexOptions.Compiled);

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

        // Find matches using case-insensitive regular expression.
        MatchCollection matches = rxInsensitive.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);
        }
        Console.WriteLine();

        // Find matches using case-sensitive regular expression.
        matches = rxSensitive.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 
//        
//       2 matches found in: 
//          The the quick brown fox  fox jumped over the lazy dog dog. 
//       'fox' repeated at positions 20 and 25 
//       'dog' repeated at positions 50 and 54

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

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