Question 1

public​ class A : B, C
Which of the following statements is TRUE regarding the above declaration?
A) ​A is the base class.
B) ​B is the derived class.
C) ​C is an interface.
D) ​All of the above are correct.

Accepted Answer

In the given declaration, "A" is a class that is inheriting from "B" and implementing the interface "C". This means "B" is the base class, "A" is the derived class, and "C" is indeed an interface.

Question 2

To add dynamic link library components, add a reference to the components in your program and include a using directive. The reason for adding the using directive is to ____.
A) enable the program to use class members
B) avoid fully qualifying references to class members
C) eliminate the syntax errors
D) enable an executable to be created

Accepted Answer

Including a using directive allows for shorter and more readable code by avoiding the need to fully qualify every reference to class members. It does not enable the program to use class members or eliminate syntax errors, and it is not directly related to creating an executable.

Question 3

A generic class is defined ____ on the class definition line.
A) by inserting an identifier between left and right parentheses
B) by inserting the word generic
C) by removing the type
D) by inserting an identifier between left and right brackets

Accepted Answer

A generic class is defined by inserting an identifier between left and right brackets. For example, `class MyClass<T> { //... }` defines a generic class called MyClass that takes a type parameter T.

Question 4

Which keyword instructs the compiler to infer the type of the variable from the expression on the right side of the initialization statement?
A) dynamic
B) type
C) infer
D) var

Accepted Answer

The keyword "var" instructs the compiler to infer the type of the variable from the expression on the right side of the initialization statement. This allows for more concise and readable code, as the programmer does not need to explicitly declare the variable type.

Question 5

Use the ____ keyword to mark a class so that it can be used only as the base class from which other classes can be derived.
A) base
B) interface
C) virtual
D) abstract

Accepted Answer

The keyword "abstract" is used to mark a class as abstract, which means it cannot be instantiated and can only be used as a base class for other classes. This ensures that any class derived from it must implement its abstract methods, making it a suitable choice for a class that is intended to be used as a base class. The other options (base, interface, and virtual) do not serve this purpose.

Question 6

If you do not want subclasses to be able to provide new implementation details, you can add the keyword ____ to methods. Doing so keeps derived classes from being able to override the method.
A) partial
B) abstract
C) virtual
D) sealed

Accepted Answer

The keyword "sealed" restricts derived classes from being able to override a method.

Question 7

Determining which method to call at runtime based on which object invokes the method describes ____.
A) abstraction
B) virtual method calls
C) dynamic binding
D) encapsulation

Accepted Answer

Dynamic binding allows the program to determine which method to call at runtime based on the object that invokes the method. This is often used in object-oriented programming languages to allow for polymorphism and improve code flexibility. Abstraction and encapsulation are related concepts but do not directly refer to determining which method to call at runtime. Virtual method calls are a specific example of dynamic binding.

Question 8

____ classes cannot be instantiated. ____ classes cannot be inherited.
A) Abstract, Sealed
B) Sealed. Abstract
C) Abstract, Abstract
D) Sealed, Sealed

Accepted Answer

Abstract classes cannot be instantiated as they are incomplete classes that have some unimplemented methods that need to be defined by the derived class. Sealed classes cannot be inherited as they are intended to be used as leaf classes in the class hierarchy and should not be extended further. Therefore, the correct answer is Option A) Abstract, Sealed.

Question 9

In order to inherit from a user-defined base class, you must ____.
A) store both files in the same directory
B) add the base class following a colon
C) add a reference to the base class
D) store both files using the same extension

Accepted Answer

To inherit from a user-defined base class in C++, you must add the base class following a colon. This is called inheritance and allows the derived class to inherit and use the properties and methods of the base class. The location and extension of the files do not affect the inheritance relationship.

Question 10

Variables declared as dynamic ____.
A) require boxing or casting to identify the actual data type
B) can hold any type of value
C) stores data as strings
D) must have an associated data type added as part of the declaration

Accepted Answer

Dynamic variables can hold any type of value and do not require an associated data type to be declared at the time of initialization.

Question 11

Calls to the ToString( ) method emphasize the use of ____.
A) encapsulation
B) inheritance
C) abstraction
D) polymorphism

Accepted Answer

The ToString() method in object-oriented programming is a prime example of polymorphism. This is because when you call ToString(), the version of the method that executes depends on the runtime type of the object it's called on, not the compile-time type. This allows objects of different types to respond to the same method call in different ways, which is the essence of polymorphism.

Question 12

Multiple inheritance is not possible in C#; ____ provides the closest work around to this because a class can implement multiple ____.
A) interfaces
B) abstract classes
C) virtual classes
D) components

Accepted Answer

Multiple inheritance is not supported in C# due to concerns about ambiguity and complexity. However, C# allows a class to implement multiple interfaces, which can provide similar functionality as multiple inheritance. Interfaces define a set of methods and properties that a class must implement, allowing for greater flexibility in defining relationships between classes. Abstract classes and virtual classes can provide some level of inheritance, but they don't allow a class to inherit from multiple base classes at once. Components are a general term in programming and don't specifically relate to this question.

Question 13

public static void ExchangeContents (ref T value1, ref T value2) {
T temp;
Temp = value1;
Value1 = value2;
Value2 = temp;
}
​Which of the following is TRUE regarding the above segment of code?
A) ​The segment of code is defining a generic method.
B) ​T is a placeholder for the data type.
C) ​Data in the memory locations value1 and value2 are swapped.
D) ​All of the above

Accepted Answer

The segment of code is defining a generic method using the placeholder T for the data type. The method swaps the values stored in the memory locations referenced by the input parameters value1 and value2. Therefore, option C is also correct.

Question 14

____ contain no implementation details for any of their methods.  Instead all their members are considered abstract.
A) Abstract classes
B) Interfaces
C) Virtual classes
D) Base classes

Accepted Answer

Interfaces contain only method signatures and no implementation details, unlike abstract classes that can contain both abstract and non-abstract members. Virtual classes and base classes are not standard terminology in OOP.

Question 15

When you add the virtual keyword to a method heading, it ____.
A) overrides a method from a base class.
B) tags the method as capable of being overridden.
C) converts the class to an abstract class.
D) forces all classes derived from that class to include implementation details for the method.

Accepted Answer

Adding the virtual keyword to a method heading tags the method as capable of being overridden by a method in a derived class.

Question 16

The distinguishing characteristic of an abstract method is ____.
A) no implementation details are included
B) they cannot be included in abstract classes
C) no parameters are found in the heading for the method
D) methods may not include a return type

Accepted Answer

The distinguishing characteristic of an abstract method is that it has no implementation details. An abstract method only provides a signature without any implementation, and the implementation is left to its concrete subclasses.

Question 17

One way to write reusable code is to use the object data type for instance data members. Doing so then requires ____.
A) moving the data type into a predefined type
B) using a stack to store the items
C) casting and unboxing the data type
D) creating generic classes

Accepted Answer

Using the object data type for instance data members requires casting and unboxing because 'object' is a base type in C# that can hold any data type, but when retrieving the data, it must be cast back to its original type, which involves unboxing if it was a value type.

Question 18

The base default constructor is called by ____.
A) adding base( ):  between the constructor heading and the opening curly brace
B) typing base( ): as the first executable statement in the derived constructor
C) adding className( ):  between the constructor heading and the opening curly brace
D) typing base( ): as the first executable statement in the Main( ) method

Accepted Answer

The answer of The base default constructor is called by...

Question 19

​Prior to the introduction of generics, one way to write reusable code was to use the ____  data type for instance data members.
A) ​interface
B) ​object
C) ​var
D) ​string

Accepted Answer

Before the introduction of generics, the "object" data type was commonly used for instance data members to achieve code reusability. This is because "object" is the base class for all data types in .NET, allowing any type of data to be stored in an "object" variable.

Question 20

Abstract classes can include ____.
A) regular data field and method members
B) only virtual methods
C) only abstract methods
D) properties and virtual methods

Accepted Answer

The answer of Abstract classes can include ____.
A) regular data...

Quiz 11: Advanced Object-Oriented Programming Features

public class A : B, C Which of the following statements is TRUE regarding the above declaration?

To add dynamic link library components, add a reference to the components in your program and include a using directive. The reason for adding the using directive is to ____.

A generic class is defined ____ on the class definition line.

Which keyword instructs the compiler to infer the type of the variable from the expression on the right side of the initialization statement?

Use the ____ keyword to mark a class so that it can be used only as the base class from which other classes can be derived.

If you do not want subclasses to be able to provide new implementation details, you can add the keyword ____ to methods. Doing so keeps derived classes from being able to override the method.

Determining which method to call at runtime based on which object invokes the method describes ____.

classes cannot be instantiated. classes cannot be inherited.

In order to inherit from a user-defined base class, you must ____.

Variables declared as dynamic ____.

Calls to the ToString( ) method emphasize the use of ____.

Multiple inheritance is not possible in C#; provides the closest work around to this because a class can implement multiple .

public static void ExchangeContents (ref T value1, ref T value2) { T temp; Temp = value1; Value1 = value2; Value2 = temp; } Which of the following is TRUE regarding the above segment of code?

____ contain no implementation details for any of their methods. Instead all their members are considered abstract.

When you add the virtual keyword to a method heading, it ____.

The distinguishing characteristic of an abstract method is ____.

One way to write reusable code is to use the object data type for instance data members. Doing so then requires ____.

The base default constructor is called by ____.

Prior to the introduction of generics, one way to write reusable code was to use the ____ data type for instance data members.

Abstract classes can include ____.