C# Delegates in .NET

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Questions and Answers

What is a delegate in.NET?

A method in C#

A reference type data type that holds a reference to a method (correct)

An object-oriented programming concept

A class that encapsulates data

How should a delegate be declared in C#?

By providing the implementation details

By specifying the return type, name, and parameters (correct)

Using the 'class' keyword

By using public access modifier only

What does the 'delegate' keyword do in C#?

Declares a reference variable

Declares a delegate type (correct)

Defines a new class

Creates an instance of an object

How is a delegate instantiated in C#?

By using the 'new' keyword associated with the method Signup and view all the answers

In C#, what is the purpose of declaring a delegate?

To hold a reference to a method Signup and view all the answers

What happens when the += operator is used to add an event to a class?

Two event accessors, add and remove, are automatically generated Signup and view all the answers

Which namespace in .NET Framework contains standard types for managing collections of objects?

System.Collection Signup and view all the answers

What is a characteristic of an ArrayList in C#?

It is known as a dynamic collection since items can be added and removed Signup and view all the answers

What does a Hashtable in C# store?

Key or value pairs Signup and view all the answers

How do standard collections differ from generic collections in .NET Framework?

Standard collections are found in System.Collections namespace while generic collections are in System.Collections.Generic namespace Signup and view all the answers

What is a key difference between delegates and interfaces in C#?

Delegates can reference any method of a class with arguments and return types. Signup and view all the answers

Which statement about delegates in C# is true?

Delegates have no implementation and are just safe callbacks. Signup and view all the answers

How are events usually initiated in C#?

Through registering methods using delegates. Signup and view all the answers

What role do event handlers play in C# when an event occurs?

Event handlers are automatically invoked when an event occurs. Signup and view all the answers

Why are interfaces slower in executing but faster to get compared to delegates in C#?

Because interfaces can extend functionality but do not implement methods. Signup and view all the answers

Study Notes

Delegates in .NET

A delegate is a type that represents references to methods, facilitating method calls indirectly.
Declaring a delegate in C# involves using the delegate keyword followed by the return type and method signature.
The delegate keyword defines a delegate type, allowing for encapsulation of method references.
Delegates are instantiated in C# by specifying the delegate type and assigning it a method reference.
Declaring a delegate serves the purpose of enabling the invocation of methods passed as parameters, promoting flexibility in coding.

Event Handling with Delegates

Using the += operator adds an event handler to a class, allowing multiple methods to respond to an event.
Events are typically initiated by calling the delegate associated with the event, effectively notifying subscribers.

Collections in .NET Framework

The System.Collections namespace in .NET Framework contains standard types for managing collections of objects.
An ArrayList in C# is characterized by its ability to dynamically resize, storing elements of any type in a single collection.
A Hashtable in C# stores key-value pairs, enabling fast retrieval of values based on unique keys.

Standard vs Generic Collections

Standard collections (like ArrayList and Hashtable) can store any data type but may require type casting, leading to runtime errors.
Generic collections provide type safety, usually yielding better performance and avoiding runtime type checks.

Delegates vs Interfaces

A key difference between delegates and interfaces is that delegates can point to multiple methods, while interfaces define a contract that a class must fulfill.
Delegates can be more efficient than interfaces as they utilize less overhead, making them faster in method invocation.

Event Handlers in C#

Event handlers are special methods designated to respond to specific events, executed when the respective event occurs.
A true statement about delegates in C# is that they support asynchronous method calls through invocation lists.
Interfaces may be slower in executing due to the added overhead of ensuring the contract but are faster to retrieve since they provide a structured way to access functionality.

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Description

Learn about the Delegate class in .NET, a reference type data type used to encapsulate methods. Explore how to declare and instantiate a delegate, specifying the return type and access modifiers. Understand how delegates can call any method with a matching signature.