Regex Constructor (String, RegexOptions)

The pattern parameter consists of regular expression language elements that symbolically describe the string to match. For more information about regular expressions, see the .NET Framework Regular Expressions and Regular Expression Language - Quick Reference topics.

A Regex object is immutable, which means that it can be used only for the match parameters you define when you create it. However, it can be used any number of times without being recompiled.

This constructor creates a Regex object that uses the default time-out value of the application domain in which it is created. If a time-out value has not been defined for the application domain, the Regex object uses the value InfiniteMatchTimeout, which prevents the operation from timing out. The recommended constructor for creating a Regex object is Regex.Regex(String, RegexOptions, TimeSpan), which lets you set the time-out interval.

The following example illustrates how to use this constructor to instantiate a regular expression that matches any word that begins with the letters "a" or "t".

string pattern = @"\b[at]\w+";
RegexOptions options = RegexOptions.IgnoreCase | RegexOptions.Compiled;
string text = "The threaded application ate up the thread pool as it executed.";
MatchCollection matches;

Regex optionRegex = new Regex(pattern, options);
Console.WriteLine("Parsing '{0}' with options {1}:", text, options.ToString());
// Get matches of pattern in text
matches = optionRegex.Matches(text);
// Iterate matches 
for (int ctr = 0; ctr < matches.Count; ctr++)
   Console.WriteLine("{0}. {1}", ctr, matches[ctr].Value);

Note that the match collection includes the word "The" that begins the text because the options parameter has defined case-insensitive comparisons.

.NET Framework

.NET Framework Client Profile

Portable Class Library

.NET for Windows Store apps

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.

Reference

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