Chapter 17. Strings

There was a time when people thought of computers as manipulating numeric values exclusively. 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.

The .NET Framework provides a String class (upper case S). The C# language offers an alias to the String class as the string class (lowercase s). These classes are interchangeable, and you are free to use either upper- or lowercase.

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 sub-strings, manipulate and concatenate strings, and build new strings with the StringBuilder class. In addition, you will find a short introduction to the RegEx class used to match strings based on regular expressions.