Overview

Below are generic delegates useful for manipulating arrays and lists.

Action<T>

Represents a method that performs some action on an element of the specified type.

Usage:

1. Create a method that performs the desired action on an element
2. Create an instance of the Action<T> delegate
3. Pass the array and the delegate to the Array.ForEach static generic method

Note: List<T> also has a ForEach method that uses an Action<T> delegate, but this method is not generic.

Predicate<T>

Represents a method that determines whether a particular element meets defined criteria.

Usage:

1. Create a method that performs the desired test
2. Create an instance of the Predicate<T> delegate
3. Call Array’s methods that use this delegate: Exists, Find, FindAll, FindIndex, FindLast, FindLastIndex, TrueForAll.

Note: List<T> also has instance methods that accept Predicate<T>.

Comparison<T>

Use to provide a sort order for an array or list that does not have a native sort order.

Usage:

1. Create a method that performs the comparison
2. Create an instance of the Comparison<T> delegate
3. Call the Array.Sort<T> or List<T>.Sort() methods

Converter<T>

Use to define a conversion between two types including between arrays of different types and between lists of different types.

Usage:

1. Create a method that converts the elements of the existing list to a new type
2. Create an instance of the Converter<T> delegate
3. Call the Array.ConvertAll or List<T>.ConvertAll methods