30.7. Regular Expressions, Class Pattern and Class Matcher

Regular expressions are sequences of characters and symbols that define a set of strings. They are useful for validating input and ensuring that data is in a particular format. For example, a ZIP code must consist of five digits, and a last name must contain only letters, spaces, apostrophes and hyphens. One application of regular expressions is to facilitate the construction of a compiler. Often, a large and complex regular expression is used to validate the syntax of a program. If the program code does not match the regular expression, the compiler knows that there is a syntax error within the code.

Class String provides several methods for performing regular-expression operations, ...

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