MCQs on C# Delegates and Events | C#

200+ FREE C# Intermediate MCQs Quiz | MCQs on C# MCQs on C# Delegates and Events | C#

Enhance your C# skills with 30 multiple-choice questions on Delegates and Events. Topics include delegate types (Action, Func, Predicate), event handling, multicast delegates, and lambda expressions.

Chapter 9: C# Delegates and Events

Understanding Delegates

What is a delegate in C#?
- a) A pointer to a method
- b) A reference to an object
- c) A class that performs calculations
- d) A collection of methods
Which keyword is used to declare a delegate in C#?
- a) delegate
- b) event
- c) void
- d) function
How do you instantiate a delegate in C#?
- a) Using the new keyword with a method reference
- b) Using the delegate keyword only
- c) By assigning a method to a variable
- d) Using a constructor
What does a delegate allow in C#?
- a) It allows calling a method indirectly
- b) It binds multiple methods together
- c) It allows function overloading
- d) It performs arithmetic operations
Which of the following is true about delegates in C#?
- a) Delegates are type-safe
- b) Delegates can only reference methods with void return type
- c) Delegates are not flexible
- d) Delegates cannot be used in events
Which method can be called using a delegate?
- a) Any method matching the delegate signature
- b) Only methods with no parameters
- c) Only methods that return a value
- d) Only static methods

Delegate Types (Action, Func, Predicate)

What is the purpose of the Action delegate in C#?
- a) It represents methods that return void and take parameters
- b) It represents methods that return a value and take parameters
- c) It represents methods with no parameters
- d) It represents methods that take no parameters and return a value
What is the main difference between Func and Action delegates in C#?
- a) Func returns a value, while Action does not
- b) Func takes no parameters, while Action takes parameters
- c) Func is used for event handling, while Action is not
- d) Func is used for asynchronous methods, while Action is not
What is the Predicate delegate used for in C#?
- a) It represents methods that take a parameter and return a boolean
- b) It represents methods that take no parameters and return a boolean
- c) It represents methods that return an integer
- d) It represents methods that perform mathematical operations
Which delegate type would be used for a method that takes an integer parameter and returns a string in C#?

a) Func<int, string>
b) Action<int>
c) Predicate<int>
d) Action<string>

How many parameters can a Func delegate take in C#?

a) Up to 16 parameters
b) Only one parameter
c) Unlimited parameters
d) None, it only returns a value

Which delegate type would be appropriate to use for a method that takes no parameters and returns nothing in C#?

a) Action
b) Func
c) Predicate
d) EventHandler

What is the maximum number of parameters a Predicate delegate can take in C#?

a) One
b) Two
c) Three
d) Unlimited

Can a Func delegate be used to represent a method that does not return a value?

a) No, it must always return a value
b) Yes, but the return type must be void
c) Yes, the return type can be anything
d) No, it requires a return value

Event Handling

What is the main purpose of events in C#?

a) To allow methods to be triggered by other objects
b) To store data
c) To handle exceptions
d) To store user inputs

How are events declared in C#?

a) Using the event keyword
b) Using the delegate keyword
c) Using the public keyword
d) Using the handler keyword

What is the relationship between events and delegates in C#?

a) Events use delegates to handle method invocations
b) Events replace delegates
c) Events are declared in a method
d) Delegates cannot be used in events

Which of the following is true about event handlers in C#?

a) Event handlers are methods that are called when an event is triggered
b) Event handlers can only be invoked by delegates
c) Event handlers cannot be invoked directly
d) Event handlers cannot return a value

How can a method subscribe to an event in C#?

a) By using the += operator
b) By using the = operator
c) By using the add keyword
d) By using the subscribe method

What happens if an event has no subscribers in C#?

a) The event will never be triggered
b) The event will throw an exception
c) The event will execute an empty method
d) The event will trigger an error

Can an event be triggered by multiple subscribers in C#?

a) Yes, an event can have multiple subscribers
b) No, only one subscriber can be attached to an event
c) Yes, but only with multicast delegates
d) No, events cannot have multiple subscribers

What is the purpose of the EventHandler delegate in C#?

a) To represent methods that handle events
b) To trigger events
c) To subscribe to events
d) To call methods asynchronously

Multicast Delegates

What is a multicast delegate in C#?

a) A delegate that can hold references to multiple methods
b) A delegate that only holds one method
c) A delegate used for async operations
d) A delegate that triggers events

How do you remove a method from a multicast delegate in C#?

a) Using the -= operator
b) Using the remove keyword
c) Using the unsubscribe method
d) By calling the Clear() method

What happens when a multicast delegate is invoked in C#?

a) All methods in the delegate invocation list are called in order
b) Only the first method in the list is called
c) Only the last method in the list is called
d) No methods are called

Can a delegate have both Action and Func methods in its invocation list in C#?

a) Yes, as long as the return types match
b) No, delegates cannot have mixed return types
c) Yes, but only if the parameters are the same
d) No, it is not allowed

Lambda Expressions

What is the syntax for a lambda expression in C#?

a) (parameter) => expression
b) parameter => expression
c) expression => parameter
d) parameter -> expression

How do lambda expressions improve code readability in C#?

a) They allow writing inline methods for simple operations
b) They require less memory than regular methods
c) They allow using multiple delegates in one statement
d) They automatically handle event subscriptions

What is the return type of a lambda expression in C#?

a) It can be inferred based on the expression
b) It must always be void
c) It must be explicitly specified
d) It must always be a boolean

What does the => symbol in a lambda expression represent in C#?

a) It separates the parameters from the expression
b) It assigns the result of an expression to a variable
c) It indicates the type of the expression
d) It separates multiple expressions in a delegate

Answer Key

Qno	Answer
1	a) A pointer to a method
2	a) `delegate`
3	a) Using the `new` keyword with a method reference
4	a) It allows calling a method indirectly
5	a) Delegates are type-safe
6	a) Any method matching the delegate signature
7	a) It represents methods that return void and take parameters
8	a) `Func` returns a value, while `Action` does not
9	a) It represents methods that take a parameter and return a boolean
10	a) `Func<int, string>`
11	a) Up to 16 parameters
12	a) `Action`
13	a) One
14	a) No, it must always return a value
15	a) To allow methods to be triggered by other objects
16	a) Using the `event` keyword
17	a) Events use delegates to handle method invocations
18	a) Event handlers are methods that are called when an event is triggered
19	a) By using the `+=` operator
20	a) The event will never be triggered
21	a) Yes, an event can have multiple subscribers
22	a) To represent methods that handle events
23	a) A delegate that can hold references to multiple methods
24	a) Using the `-=` operator
25	a) All methods in the delegate invocation list are called in order
26	a) Yes, as long as the return types match
27	a) `(parameter) => expression`
28	a) They allow writing inline methods for simple operations
29	a) It can be inferred based on the expression
30	a) It separates the parameters from the expression

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