Here, We see C# LinkedIn Skill Assessment Answers. This assessment test consists 15-20 MCQs to demonstrate your knowledge in your selected skills. MCQs comes from different topics – C# Assemblies and Extensions, C# Communication, C# Fundamentals, C# Networking, C# Objects and Types.
Table of Contents
Q1. In which of these situations are interfaces better than abstract classes?
- When you need to define an object type’s characteristics, use an interface. When you need to define an object type’s capabilities, use an abstract class.
- Interfaces are a legacy of older versions of C#, and are interchangeable with the newer abstract class feature.
- When you need a list of capabilities and data that are classes-agnostic, use an interface. When you need a certain object type to share characteristics, use an abstract class.✔️
- You should use both an interface and an abstract class when defining any complex object.
Q2. Which statement is true of delegates?
- Delegates are not supported in the current version of C#
- They cannot be used as callbacks.
- Only variables can be passed to delegates as parameters.
- They can be chained together.✔️
Reference Official documentation: Delegates
Q3. Which choice best defines C#’s asynchronous programming model?
- reactive
- inherited callback
- task-based✔️
- callback-based
Reference Official documentation: Task asynchronous programming model
Q4. How would you determine if a class has a particular attribute?
- A
var type = typeof(SomeType);
var attribute = type.GetCustomAttribute<SomeAttribute>();
- B
var typeof(MyPresentationModel).Should().BeDecoratedWith<SomeAttribute>();
- C
Attribute.GetCustomAttribute, typeof(SubControllerActionToViewDataAttribute)
- D ✔️
Attribute.GetCustomAttribute(typeof(ExampleController), typeof(SubControllerActionToViewDataAttribute))
Reference Official documentation: Attribute Class
Reference Official documentation: Attribute.GetCustomAttribute Method
Q5. What is the difference between the ref and out keywords?
- Variables passed to out specify that the parameter is an output parameter, while ref specifies that a variable may be passed to a function without being initialized.
- Variables passed to ref can be passed to a function without being initialized, while out specifies that the value is a reference value that can be changed inside the calling method.
- Variables passed to out can be passed to a function without being initialized, while ref specifies that the value is a reference value that can be changed inside the calling method.✔️
- Variables passed to ref specify that the parameter is an output parameter, while out specifies that a variable may be passed to a function without being initialized.
Reference Official documentation: ref
Reference Official documentation: out parameter modifier
Q6. How could you retrieve information about a class, as well as create an instance at runtime?
- reflection✔️
- serialization
- abstraction
- dependency injection
Reference Official documentation: Reflection
Q7. What is this code an example of?
private static object objA;
private static object objB;
private static void performTaskA()
{
lock (objB)
{
Thread.Sleep(1000);
lock (objA) { }
}
}
private static void PerformTaskB()
{
lock (objA)
{
lock (objB) { }
}
}
- a private class that uses multithreading
- multithread coding
- thread mismanagement
- a potential deadlock✔️
Reference Official documentation: Deadlocks and race conditions
Q8. What is the difference between an anonymous type and a regular data type?
- Anonymous types don’t have type names✔️
- Anonymous types can only be static
- Anonymous types can be used only in struts
- Anonymous types don’t work with LINQ.
Reference Official documentation: Anonymous Types
Q9. When would you use a Dictionary rather that an Array type in your application?
- when you need a jagged collection structure
- when you need to store values of the same type
- when you need to store key-value pairs rather than single values✔️
- when you need an ordered, searchable list
Reference Official documentation: Dictionary<TKey,TValue> Class
Q10. What is the difference between a.Equals(b) and a == b?
- The .Equals method compares reference identities while the == compares contents.
- The .Equals method compares primitive values while == compares all values.
- The .Equals method compares contents while == compares references reference identity.✔️
- The .Equals method compares reference type while == compares primitive value types.
Q11. Which choice best describes a deadlock situation?
- when you try to instantiate two objects at the same time in the same class or struct
- when you are trying to execute an action after a user event is registered
- when simultaneous instructions are waiting on each other to finish before executing✔️
- when you try to execute a series of events simultaneously on multiple threads
Reference Official documentation: Deadlocks and race conditions
Q12. How does the async keyword work?
- It allows access to asynchronous methods in the C# API
- It allows thread pooling and synchronous processes in static classes.
- It allows the await keyword to be used in a method✔️
- It allows access to synchronous methods in the C# API
Reference Official documentation: async
Q13. What is an object in C#?
- a class or struct, including its variables and functions
- a primitive data type that can be created only at compile time
- a value type that can be used only with an abstract class
- an instance of a class or struct that includes fields, properties, and/or methods✔️
Reference Official documentation: Objects
Q14. Which code snippet declares an anonymous type named userData?
var<<!---->T> userData = new <<!---->T> { name = "John", age = 32 };
var userData = new { name = "John", age = 32 };
✔️AType userData = new AType { name = "John", age = 32 };
Anonymous<T> userData = new Anonymous<T> { name = "John", age = 32 };
Reference Official documentation: Anonymous Types
Q15. What will be returned when this method is executed?
public void userInput(string charParamters) { }
- nothing✔️
- a Boolean
- a string variable
- an integer
Reference Official documentation: void
Q16. In what order would the employee names in this example be printed to the console?
string[] employees = { "Joe", "Bob", "Carol", "Alice", "Will" };
IEnumerable<string> employeeQuery = from person in employees
orderby person
select person;
foreach(string employee in employeeQuery)
{
Console.WriteLine(employee);
}
- ascending✔️
- unordered
- descending
- first in, first out
Reference dotnetpattern: LINQ OrderBy Operator
Q17. Lambda expressions are often used in tandem with which of the following?
- Namespaces
- LINQ✔️
- Type Aliasing
- Assemblies
Reference Official documentation: Language Integrated Query (LINQ) Overview
Q18. What is the correct formatting for single line and multiline comments?
- // – Single Line / – Multiline
- // Multiline /_ Single Line _/
- //* Multiline / Single Line
- *// Single Line /_ Multiline _/✔️
Reference w3schools: C# Comments
Q19. How do you make a method in an abstract class overridable?
- Make it public
- Make it static
- Make it private
- Make it virtual✔️
Reference Official documentation: virtual
Reference Official documentation: abstract
Q20. How would you write code for an integer property called Age with a getter and setter?
- public int Age { get – set }
- public int Age: get set;
- public int Age (get, set );
- public int Age { get; set; }✔️
Reference Official documentation: Using Properties
Q21. What is an abstract class?
- a class that is denoted by the class keyword (can be seen and used by any other class in the system–thus it is by default public)
- something denoted by the abstract keyword and used system wide; if you want any program to create an object of a class you use the abstract class
- a class that is denoted by the virtual keyword
- a class that can be used only as base class✔️
Reference Official documentation: Abstract and Sealed Classes and Class Members
Q22. When using a thread pool what happens to a given thread after it finishes its task?
- The thread is destroyed and memory is freed up.
- The thread runs in loop until the next assignment.
- The thread goes inactive in the background and waits for garbage collection.✔️
- The thread returns to the pool for reuse.
Reference Official documentation: ThreadPool Class
Reference Official documentation: Thread Class
Q23. Which choice represents a class that inherits behavior from a base class?
- a second base class
- a revised class
- a derived class✔️
- a parent class
Reference Official documentation: Inheritance
Q24. What does operator overloading allow you to do?
- hide built-in operatores when necessary
- add methods to be interpreted by the compiler at runtime
- define how enums and other primitive value types work within the rest of the application
- define custom functionality for common operators like addition and equality✔️
Reference Official documentation: Operator overloading
Q25. What it the main purpose of LINQ?
- to delete duplicate data
- to bind namespaces and assemblies
- to query and transform data✔️
- to connect assemblies
Reference Official documentation: Language Integrated Query (LINQ) Overview
Q26. What is the correct syntax for a new generic list of strings named contacts?
- public List<string names> contacts = new List<string names>();
- public List(string names) contacts = new List(string names)();
- var contacts = new List<string>();✔️
- var contacts = new List(string);
Reference Official documentation: List<T> Class
Q27. What is the difference between throw exceptions and throw clauses?
- Throw clauses fire only at runtime, while throw exceptions can fire at any time.
- Throw exceptions overwrite the stack trace, while throw clauses retain the stack information.✔️
- Throw clauses overwrite the stack trace, while throw exceptions retain the stack information.
- Throw exceptions fire only at runtime, while throw clauses can fire during compile time.
Reference Official documentation: throw
Reference c-sharpcorner: Difference Between Throw Exception and Throw Clause
Q28. When an asynchronous method is executed, the code runs but nothing happens other than a compiler warning. What is most likely causing the method to not return anything?
- The return yield statement is missing at the end of the method.
- The method is missing an await keyword in its body.✔️
- The wait keyword is missing from the end of the method.
- The yield keyword is missing from the method.
Q29. What are C# events?
- system actions that communicate directly with the compiler at runtime
- actions that execute when the code compiles, generating logs and test output
- actions that generate notifications, which are sent to their registered listeners✔️
- user-only methods that send data to the application’s back end
Reference Official documentation: Introduction to events
Q30. What kind of values can arrays store?
- unordered collections of numerc values
- key-value pairs of any C# supported type
- class and struct instances
- multiple variables, or collections, of the same type✔️
Reference Official documentation: Arrays
Q31. Given this enumeration, how would you access the integer-type value of ‘AppState.Loading’?
enum AppState { OffLine, Loading, Ready }
- string currentState = (string)AppState.Loading;
- string currentState = AppState.Loading.integralVal;
- int currentState = AppState.Loading.rawValue;
- int currentState = (int)AppState.Loading;✔️
Reference Official documentation: Enumeration types
Q32. What character would you use to start a regular expression pattern at a word boundary?
- d
- \a
- \b✔️
- \w
Reference regular-expressions: Word Boundaries
Reference Official documentation: Regular Expression Language – Quick Reference
Q33. To conform to the following interface, which of its members need to be implemented?
public interface INameble
{
string FirstName { get; set; }
string LastName { get; }
}
- Both the FirstName and LastName properties need to be implemented.✔️
- Neither, they are both optional.
- Only the LastName property needs to be implemented.
- Only the FirstName property needs to be implemented.
Reference Official documentation: interface
Q34. You’re dealing with multiple assemblies in your program, but are worried about memory allocation. At what point in the program life cycle are assemblies loaded into memory?
- at runtime
- at compile time
- only when required✔️
- only when programmatically loaded
Q35. What is most accurate description of a regular expression?
- A regular expression is a C# tool used to parse HTML
- A regular expression is a special text string for describing a search patters.✔️
- A regular expression allows a variable to be passed by reference.
- A regular expression allows a class to conform to the Equatable protocol.
Reference Official documentation: Regular Expression Language – Quick Reference
Reference Official documentation: .NET regular expressions
Q36. Why would you use a class field in C#
- To define behaviours of the class
- To hold information and data contained in the class object✔️
- To communicate between classes and object
- To store the class definition value
Reference Official documentation: Introduction to classes
Q37. When would you use generics in your code?
- to increase code performance
- all of these answers✔️
- when code reuse is a priority
- when type safety is important
Reference Official documentation: Generic classes and methods
Q38. What prints to the console when this code is executed?
public delegate void AuthCallback(bool validUser);
public static AuthCallback loginCallback = Login;
public static void Login()
{
Console.WriteLine("Valid user!");
}
public static void Main(string[] args)
{
loginCallback(true);
}
- Login successful…
- Valid user!
- an error, because the method signature of Login doesn’t match the delegate✔️
- Login successful… Valid user!
Reference Official documentation: Introduction to Delegates
Reference Official documentation: Introduction to Events
Q39. How would you declare a sealed class named User?
- public class User
- abstract User {}
- sealed class User✔️
- private sealed class User
Reference Official documentation: Abstract and Sealed Classes and Class Members
Q40. What is the correct syntax for a new generic list of strings named contacts? (similar to Q26)
var contacts = new List<string>();
✔️var contacts = new List(string);
public List<string names> contacts = new List<string names>();
public List(string names) contacts = new List(string names);
Reference Official documentation: List<T>
Q41. What is the difference between non-static and static classes?
- non-static classes need to be initialized before use, while static classes do not✔️
- non-static classes are accessible only from an interface while static classes are accessible from anywhere
- non-static classes need to initialize all class members at runtime, while static classes do not
- non-static classes do not need to be initialized while static classes do
Reference stackoverflow
Reference Official documentation: Static Constructors
Q42. Which characteristic prevents this code from compiling?
public int age="28"
- type safety✔️
- single inheritance
- dependency injection
- multiple inheritance
Reference c-sharpcorner: Type Safety in .NET
Q43. How would you serialize this class?
public class User {}
- Mark the User class with the
DeserializableAttribute
. - Declare the class as
public serializable class User {}
. - Mark the User class with the
SerializableAttribute
attribute.✔️ - Declare the class as
private serializable class User {}
.
Reference Official documentation: SerializableAttribute Class
Q44. How would you write a delegate named ResultCallback with an int parameter named responseCode
- public delegate ResultCallback(int responseCode)
- public delegate void ResultCallback<(int) responseCode>;
- public void delegate ResultCallback<int responseCode>;
- public delegate void ResultCallback(int responseCode);✔️
Reference Official documentation: Delegates
Q45. What is the difference between a static and non-static method?
- non-static methods always need to have a void return type
- non-static methods do not have access to static member variables
- static methods do not have to instantiate an instance of the class to call the method✔️
- static methods always have to be public
Reference Official documentation: Static Members
Q46. What is the correct way to write an event named apiResult based on a delegate named ResultCallback?
- public void event ResultCallback apiResult;
- public event ResultCallback(() -> apiResult);
- public event void ResultCallback
- public event ResultCallback apiResult;✔️
Reference Official documentation: Introduction to events
Q47. When will the code inside finally block be executed in a try-catch statement?
- if there is an error, it won’t execute at all
- between the try and catch blocks
- after the try and catch blocks✔️
- when the finally block overrides the catch block and executes in its place
Reference Official documentation: try-catch
Q48. What method correctly extends the string class?
- public static string IsvalidName(this string i, string value) {}✔️
- public static void IsvalidName(this string i, string value) {}
- public string IsvalidName(this string i, string value) {}
- public void IsvalidName(this string i, string value) {}
Q49. How are C# classses limited?
- They do not support multiple inheritance.
- They support multiple inheritance.
- They can have only a set number of properties.
- They can have only a set number of methods.
Reference Official documentation: Class inheritance
Q50. What function do namespaces perform?
- Namespaces calculate code coverage at runtime.
- Namespaces compile application code together at compile time.
- Namespaces group code together into a single repository.
- Namespaces separate code into groupings, control access, and void naming collisions.✔️
Reference Official documentation: namespace
Q51. What is the correct way to write a public property with a private backing field?
- A
private int _password;
pubic int Password = { get; set; }
- B
private int _password;
public int Password = _password;
- C
private int _password;
public int Password
{
get -> _password;
set-> _password = value;
}
- D ✔️
private int _password;
public int Password
{
get { return _password; }
set { _password = value; }
}
Reference Official documentation: Using Properties
Q52. What is a thread pool?
- a collection of synchronous methods created during initialization that cannot be reused
- a collection of threads created during initialization that can be reused✔️
- a collection of threads only recognized at compile time that can be reused
- a collection of asynchronous methods created at compile time that cannot be reused
Reference Official documentation: ThreadPool Class
Q53. What is the most accurate description of a regular expression?
- A regular expressions allows a variable to be passed by reference
- A regular expression allows a class to conform to the Equatable protocol
- A regular expression is a C# tool used to parse HTML
- A regular expression is a special text string for describing a search pattern✔️
Reference Official documentation: Regular Expression Language – Quick Reference
Q54. When an object in C# is serialized, what is it converted to?
- XML
- JSON
- byte stream✔️
- value stream
Reference: Official documentation: Serialization
Q55. What is a delegate
- a variable that holds a reference to a value type and its content
- a specific value type that can be used only in callback methods
- a type that holds a reference to a method with a particular parameter list and return type✔️
- a custom variable type that can be used in abstract classes
Reference: Official documentation: Delegates
Q56. What are the four keywords associated with exception handling in C#?
- try, catch, valid, invalid
- try, valid, finally, throw
- try, catch, finally, throw✔️
- finally, throw, valid, invalid
Reference: Tutorial Point
Q57. What is the main difference between the is and as operators?
- The is operator checks instance types, while the as operator checks the inherited type.
- The is operator checks primitive data types, while the as operator checks the object type.
- The as operator checks object type, while the is operator attempts to cast an object to a specific type.
- The is operator checks object type, while the as operator attempts to cast an object to a specific type.✔️
Reference: Pluralsight guide
Q58. What is the difference between finally and finalize blocks?
- The finally block is called during the execution of a try and catch block, while the finalize method is called after garbage collection.
- The finally block is called after the execution of a try and catch block, while the finalize method is called just before garbage collection.✔️
- The finalize block is called before the execution of a try and catch block, while the finally method is called just before garbage collection.
- The finalize block is called during the execution of a try and catch block, while the finally method is called after garbage collection.