Delegates

What is a delegate in C#?

• A class that encapsulates a method signature

• A pointer to a function

• A type-safe function pointer

• A reserved keyword for asynchronous programming

Answer explanation

A delegate in C# is a type-safe function pointer that can reference methods with a particular signature.

Which keyword is used to declare a delegate type in C#?

• delegate

• function

• delegateType

• method

Answer explanation

The keyword "delegate" is used to declare a delegate type in C#.

Delegates in C# support:

• Single method call

• Multicast delegates

• Both a and b

• None of the above

Answer explanation

Delegates in C# support single method call as well as multicast delegates (i.e., delegates that can point to multiple methods).

What is the return type of a delegate?

• void

• int

• string

• It depends on the method it points to

Answer explanation

The return type of a delegate depends on the method it points to.

Which of the following statements is true about multicast delegates?

• They can point to multiple methods.

• They can point to only one method.

• They cannot be invoked.

• They are obsolete in C#.

Answer explanation

Multicast delegates in C# can point to multiple methods.

Which delegate type is provided by C# for asynchronous programming?

• AsyncCallback

• AsyncDelegate

• AsyncFunction

• None of the above

Answer explanation

AsyncCallback delegate type is provided by C# for asynchronous programming.

Which keyword is used to combine two delegates into a single multicast delegate?

• join

• merge

• +

• +=

Answer explanation

The += operator is used to combine two delegates into a single multicast delegate.

What happens if a multicast delegate is invoked and one of the methods throws an exception?

• The exception is ignored.

• All subsequent methods are not invoked.

• All methods are invoked, and exceptions are aggregated.

• The program terminates.

Answer explanation

When invoking a multicast delegate, all methods are invoked, and exceptions from each method are aggregated.

Which of the following is NOT a delegate type in C#?

• Func<>

• Action<>

• Predicate<>

• Runnable<>

Answer explanation

"Runnable<>" is not a delegate type in C#. Func<>, Action<>, and Predicate<> are commonly used delegate types.

Can delegates be used to implement events in C#?

• Yes

• No

• Only with specific attributes

• Only in the .NET Core framework

Answer explanation

Delegates can be used to implement events in C#.