Question 21

What keyword returns null if a cast will not succeed?

as

is

where

using

Question 22

What keyword brings an extension method into scope?

as

is

where

using

Question 23

You can update a GUI from any thread of execution.

True

False

Question 24

What is used to implement event in C#?

Specialized DLLs

Exceptions

Delegates

No answer text provided.

Question 25

What method do you call to start a Thread in C#?

Start()

Begin()

Jump()

Init()

Question 26

What keyword is added to a delegate to force subscribers to use += or =?

event

this

delegate

none of the above

Question 27

Which of the following best describes what a delegate is?

A strongly typed function pointer.

A lightweight thread or process that can call a single method.

A reference to an object in a different process.

An interprocess message channel

Question 28

What is the value of s after the following code?

int s = 0;

for (int i = 1; i < 100;i++)

{

if (s > 10)

{ break; }

if (i % 2 == 0)

{ s += i; }

}

15

6

12

20

Question 29

In a WPF project, there is a textbox UI element named txtAge is used for age input, which of the following can properly obtain an integer value of age?

int age = txtAge;

int age = txtAge.Text;

int age = Convert.ToInt32(txtAge);

int age = int.Parse(txtAge.Text);

Question 30

When an object of a derived class is instantiated, a base class ______ is called implicitly.

method

property

constructor

event