Regex Constructor (String)
Initializes a new instance of the Regex class for the specified regular expression.
Assembly: System (in System.dll)
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 pattern you define when you create it. However, it can be used any number of times without being recompiled.
This constructor instantiates a regular expression object that attempts a case-sensitive match of any alphabetical characters defined in pattern. For a case-insensitive match, use the Regex.Regex(String, RegexOptions) constructor.Notes to Callers
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".
Note that the regular expression pattern cannot match the word "The" at the beginning of the text, because comparisons are case-sensitive by default. For an example of case-insensitive comparison, see the Regex(String, RegexOptions) constructor.
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.