Chapter 10. Strings and Regular Expressions

There was a time when people thought of computers exclusively as manipulating numeric values. Early computers were first used to calculate missile trajectories, and programming was taught in the math department of major universities.

Today, most programs are concerned more with strings of characters than with strings of numbers. Typically these strings are used for word processing, document manipulation, and creation of web pages.

C# provides built-in support for a fully functional string type. More importantly, C# treats strings as objects that encapsulate all the manipulation, sorting, and searching methods normally applied to strings of characters.

Complex string manipulation and pattern matching is aided by the use of regular expressions. C# combines the power and complexity of regular expression syntax, originally found only in string manipulation languages such as awk and Perl, with a fully object-oriented design.

In this chapter, you will learn to work with the C# string type and the .NET Framework System.String class that it aliases. You will see how to extract substrings, manipulate and concatenate strings, and build new strings with the StringBuilder class. In addition, you will learn how to use the RegEx class to match strings based on complex regular expressions.


C# treats strings as first-class types that are flexible, powerful, and easy to use. Each string object is an immutable sequence of Unicode characters. In other ...

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