Event declaration syntax in C Sharp (C#) - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the basic syntax to declare an event in C#?

An event is declared using the event keyword followed by a delegate type and the event name, like: <br>public event EventHandler MyEvent;

beginner

What delegate type is commonly used for events in C#?

The EventHandler delegate is commonly used for events. It has a signature of void(object sender, EventArgs e).

intermediate

Can you declare an event with a custom delegate type?

Yes, you can declare an event using any delegate type that matches the desired method signature. For example: <br>public delegate void MyDelegate(string message);<br>public event MyDelegate MyEvent;

beginner

What access modifiers can be used with event declarations?

Events can have access modifiers like public, private, protected, or internal to control their visibility.

intermediate

How do you raise an event inside a class?

You raise an event by calling it like a method, usually after checking if it is not null: <br>MyEvent?.Invoke(this, EventArgs.Empty);

Which keyword is used to declare an event in C#?

A interface

B event

C class

D delegate

The event keyword is used to declare events in C#.

What is the default signature of the EventHandler delegate?

A void(object sender, EventArgs e)

B int(object sender, EventArgs e)

C void()

D bool(object sender, EventArgs e)

EventHandler has the signature void(object sender, EventArgs e).

How do you check if an event has subscribers before raising it?

A Check if the event is not null

B Check if the event is zero

C Check if the event is true

D No need to check

You check if the event is not null before invoking it to avoid exceptions.

Can you declare an event with a custom delegate type?

A No

B Only with EventHandler

C Yes

D Only with Func delegates

Events can use any delegate type matching the signature you want.

Which of these is a valid event declaration?

A event public DataReceived EventHandler;

B public delegate event DataReceived;

C public event DataReceived delegate;

D public event EventHandler DataReceived;

The correct syntax is public event EventHandler DataReceived;.

Explain how to declare and raise an event in C# using the EventHandler delegate.

Think about the syntax for declaration and how to safely call the event.

Describe how you can use a custom delegate type for an event and why you might want to do that.

Consider how different event data might require different delegate signatures.