Which of the following statements about abstract classes is correct?

The correct answer is C: Can contain non-abstract methods and properties. Abstract classes can contain both abstract and non-abstract (concrete) methods and properties. They cannot be instantiated directly.

What is the time complexity for removing an element from the middle of a LinkedList?

The correct answer is A: O(1). If you have a LinkedListNode, removal is O(1). However, finding the node is O(n), so overall search + remove is O(n).

Consider: Dictionary dict = new(); dict.Add("a", 1); dict.Add("a", 2); What happens?

The correct answer is B: ArgumentException is thrown. Dictionary enforces unique keys. Attempting to add a duplicate key throws ArgumentException. Use dict["a"] = 2 to update.

Which of the following correctly declares a variable that can hold null?

The correct answer is B: int? x = null;. Only nullable types (using ?) can hold null values for value types. int? is a nullable integer that can hold null.

What does MVC stand for in ASP.NET MVC?

The correct answer is A: Model-View-Controller. MVC (Model-View-Controller) is an architectural pattern separating data (Model), presentation (View), and business logic (Controller).

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C# Programming
Basics & Syntax

C# and .NET for campus placement

56 Q 4 Topics Take Mock Test

Difficulty: All Easy Medium Hard 21–30 of 56

Topics in C# Programming

All Basics & Syntax 100 OOP in C# 100 Collections 71 ASP.NET Basics 19

Q.21 Medium Basics & Syntax

Which of the following is a correct implementation of property with auto-backing field in C#?

A public string Name { get; set; }

B public string Name { get set; }

C public string Name => _name;

D public string Name { get; private set; }_name;

Correct Answer: A. public string Name { get; set; }

EXPLANATION

Auto-properties with get; set; syntax automatically create backing fields. Option C is an expression-bodied property (read-only).

Test

Q.22 Medium Basics & Syntax

What is the output of: var x = 5; Console.WriteLine(x.GetType().Name);

A Object

B Int32

C int

D var

Correct Answer: B. Int32

EXPLANATION

The 'var' keyword declares a variable where the type is inferred at compile-time. Here, x is inferred as int, and GetType().Name returns 'Int32'.

Test

Q.23 Medium Basics & Syntax

Which statement about anonymous functions in C# is TRUE?

A Anonymous functions must have a return type

B Lambda expressions are a type of anonymous function

C Anonymous functions cannot access outer scope variables

D All anonymous functions require explicit parameter types

Correct Answer: B. Lambda expressions are a type of anonymous function

EXPLANATION

Lambda expressions (introduced in C# 3.0) are a concise form of anonymous functions. They can infer return types and parameter types, and can access outer scope variables.

Test

Q.24 Medium Basics & Syntax

What is the correct way to create a generic method in C#?

A public void Method() { }

B public void Method() { }

C public void Method[T]() { }

D public T void Method() { }

Correct Answer: A. public void Method() { }

EXPLANATION

Generic methods use angle brackets <T> after the method name. The syntax is: public void Method<T>() where T is the type parameter.

Test

Q.25 Medium Basics & Syntax

In C#, what is the difference between '==' and 'Equals()' when comparing strings?

A No difference, they are identical

B '==' compares references, Equals() compares values for strings

C 'Equals()' is slower than '=='

D '==' can compare null values safely

Correct Answer: B. '==' compares references, Equals() compares values for strings

EXPLANATION

For strings in C#, '==' is overloaded to compare values, and Equals() also compares values. However, for other reference types, '==' compares references while Equals() compares values.

Test

Q.26 Medium Basics & Syntax

Which collection type in C# automatically prevents duplicate values?

A List

B HashSet

C Queue

D Stack

Correct Answer: B. HashSet

EXPLANATION

HashSet<T> is an unordered collection that automatically prevents duplicate values. List<T> allows duplicates.

Test

Q.27 Medium Basics & Syntax

What is the output of: bool result = (5 > 3) && (10 < 8); Console.WriteLine(result);

A true

B false

C null

D error

Correct Answer: B. false

EXPLANATION

5 > 3 is true, but 10 < 8 is false. The && (AND) operator returns false because one condition is false.

Test

Q.28 Medium Basics & Syntax

Which of the following correctly demonstrates the use of an out parameter in C#?

A void Calculate(out int result) { result = 10; }

B void Calculate(in int result) { result = 10; }

C void Calculate(ref int result) { result = 10; }

D void Calculate(int result) { result = 10; }

Correct Answer: A. void Calculate(out int result) { result = 10; }

EXPLANATION

The 'out' keyword is used when a method needs to return a value through a parameter. The parameter must be assigned before the method exits.

Test

Q.29 Medium Basics & Syntax

What will be the output of the following code? int x = 5; int y = ++x; Console.WriteLine(x + " " + y);

A 5 5

B 6 6

C 5 6

D 6 5

Correct Answer: B. 6 6

EXPLANATION

++x is pre-increment, so x becomes 6, then y is assigned 6. Both x and y are 6.

Test

Q.30 Medium Basics & Syntax

Which of the following demonstrates proper use of string interpolation in C# 6.0+?

A $"Name is {name}"

B "Name is " + name

C string.Format("Name is {0}", name)

D "Name is \{name}"

Correct Answer: A. $"Name is {name}"

EXPLANATION

String interpolation uses the $ prefix followed by curly braces containing expressions.

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