Regular expressions are most useful either when you want to locate one of several substrings in a larger string, or when you want to identify patterns in a string, as the following examples illustrate. The String class includes a number of string search and replacement methods that you can use when you want to locate literal strings in a larger string.
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For examples that use the Replace method to change date formats and remove invalid characters from a string, see How to: Strip Invalid Characters from a String and Example: Changing Date Formats.įor an overview of the regular expression object model, see The Regular Expression Object Model.įor more information about the regular expression language, see Regular Expression Language - Quick Reference or download and print one of these brochures: Replace text that matches the regular expression pattern by calling the Regex.Replace method. The latter returns a MatchCollection object that contains one object for each match found in the parsed text. The former method returns a object that provides information about the matching text. Retrieve one or all occurrences of text that matches the regular expression pattern by calling the Regex.Match or Regex.Matches method. For an example that uses the IsMatch method for validating text, see How to: Verify that Strings Are in Valid Email Format. The methods of the Regex class let you perform the following operations:ĭetermine whether the regular expression pattern occurs in the input text by calling the Regex.IsMatch method. The text to parse for the regular expression pattern. For more information, see Regular Expression Language - Quick Reference. NET, regular expression patterns are defined by a special syntax or language, which is compatible with Perl 5 regular expressions and adds some additional features such as right-to-left matching.
The regular expression pattern to identify in the text. At a minimum, processing text using regular expressions requires that the regular expression engine be provided with the following two items of information: The centerpiece of text processing with regular expressions is the regular expression engine, which is represented by the object in.
Add extracted strings to a collection in order to generate a report.įor many applications that deal with strings or that parse large blocks of text, regular expressions are an indispensable tool.Extract, edit, replace, or delete text substrings.Validate text to ensure that it matches a predefined pattern (such as an email address).The extensive pattern-matching notation of regular expressions enables you to quickly parse large amounts of text to: Regular expressions provide a powerful, flexible, and efficient method for processing text.
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