LINQ for Visual C# 2008

1.3. Extension Methods

As the name implies, extension methods extend existing .NET types with new methods. For example, by using extension methods with a string, it's possible to add a new method that converts every space in a string to an underscore. Listing 1-3 provides an example of an extension method.

Example 1-3. An Extension Method

public static string SpaceToUnderscore(this string source) { char[] cArray = source.ToCharArray(); string result = null; foreach (char c in cArray) { if (Char.IsWhiteSpace(c)) result += "_"; else result += c; } return result; }

Here you define an extension method, SpaceToUnderscore(). To specify an extension method you insert the keyword this before the first method parameter, which indicates to the compiler ...