Once you have a fancy user interface set up for your application, the next step is doing something. There are plenty of great data-processing libraries in .NET for whatever your application needs.
Manipulating text is one of the most common tasks you will encounter. Because strings in .NET are immutable, it can be difficult to search and modify them. Fortunately .NET has the full support for regular expressions.
Regular expressions are a formal language for searching text for particular words or sequences of characters. You can use regular expressions in .NET to simplify processing textual data to do things like:
Validate input against a particular form
Identify substrings that match a particular structure
Create new strings that are modified versions of the input
To start with, consider the following code snippet. It defines a
=~= that takes a
string and a regular expression—the format for which we will cover
shortly—and returns if the string
matches the given regular expression. The regular expression provided,
"\d+", checks if the string contains
> // Simple regular expressions
open System.Text.RegularExpressionslet (=~=) str regex =
Regex.IsMatch(str, regex);; val ( =~= ) : string -> string -> bool > "Does this contain a number?" =~=
"\d+";; val it : bool = false > "Does this (42) contain a number?" =~=
"\d+";; val it : bool = true
Regular expressions are built on their own language of metacharacters. The ...