Question 21 Keyword Returns Null Cast Succeed Using Question 22 Keyword Brings Extension M Q29139124

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 singlemethod.
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 isused for age input, which of the following can properly obtain aninteger 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
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