A section section b explanation explanationreference

A
Section: Section B
Explanation
Explanation/Reference:

QUESTION 18
You are writing code for a new method named Process
void Draw(object o)
{
}
The code receives a parameter of type object . You need to cast this object into the type Polygon . At times,
the value of o that is passed to the method might not be a valid Polygon value. You need to make sure that
the code does not generate any System.InvalidCastException errors while doing the conversions.
Which of the following lines of code should you use inside the Draw method to accomplish this goal?
:
C
Section: Section B
Explanation
Explanation/Reference:
QUESTION 19
You are writing code to handle events in your program. You define a delegate named PolygonHandler like
this:
public delegate void PolygonHandler(Polygon p);
You also create a variable of the PolygonHandler type as follows:
PolygonHandler handler;
Later in the program, you need to add a method named CalculateArea to the method invocation list of the
handler variable. The signature of the CalculateArea method matches the signature of the
PolygonHandler method. Any code that you write should not affect any existing event-handling code. Given
this restriction, which of the following code lines should you write?
C
Section: Section B
Explanation
Explanation/Reference:
QUESTION 20
You are developing a C# application. You create a class of the name Widget . You use some third-party
libraries, one of which also contains a class of the name Widget . You need to make sure that using the

Widget class in your code causes no ambiguity. Which C# keyword should you use to address this
requirement?