C# Programming — MCQ Practice Questions & Answers

Question 1

Consider the following code. What will be the output? int x = 10; int y = 20; int z = x++ + ++y; Console.WriteLine(x + " " + y + " " + z);

Accepted Answer

Correct answer: B. 11 21 31 — x++ returns 10 then increments x to 11. ++y increments y to 21 then returns 21. z = 10 + 21 = 31. Final output: 11 21 31

Answer

A. 10 20 30

Answer

C. 11 21 30

Answer

D. 10 21 31

Question 2

Which of the following statements about structs and classes in C# is TRUE?

Accepted Answer

Correct answer: B. Structs are value types, classes are reference types — In C#, structs are value types (stored on stack) while classes are reference types (stored on heap). This is a fundamental difference between the two.

Answer

A. Structs are reference types, classes are value types

Answer

C. Both are reference types

Answer

D. Both are value types

Question 3

Which of the following is NOT a valid C# data type?

Accepted Answer

Correct answer: C. float32 — C# has float (4 bytes) and double (8 bytes), but not float32. sbyte, uint, and decimal are valid types.

Answer

A. sbyte

Answer

B. uint

Answer

D. decimal

Question 4

Consider: int[] arr = {1, 2, 3}; What happens when you try to resize it using Array.Resize(ref arr, 5)?

Accepted Answer

Correct answer: B. Creates new array with 5 elements, preserving first 3 values — Array.Resize() creates a new array of specified size and copies elements from the original array using the ref parameter.

Answer

A. Throws exception

Answer

C. Returns null

Answer

D. Changes original array size

Question 5

What is the difference between 'struct' and 'class' in C# regarding memory allocation?

Accepted Answer

Correct answer: C. struct is allocated on the stack, class on the heap — Value types (struct) are allocated on the stack, while reference types (class) are allocated on the heap.

Answer

A. Both are allocated on the heap

Answer

B. Both are allocated on the stack

Answer

D. struct is allocated on the heap, class on the stack

Question 6

Which of the following correctly describes method overloading in C#?

Accepted Answer

Correct answer: B. Methods can have the same name with different parameter types, count, or order — Method overloading allows same method name with different signatures (parameter types, count, or order). Return type alone cannot differentiate overloaded methods.

Answer

A. Methods must have the same name and same parameter list

Answer

C. Only the return type can differ between overloaded methods

Answer

D. Method overloading is not supported in C#

Question 7

In C#, what is the primary purpose of the 'using' statement?

Accepted Answer

Correct answer: B. To ensure proper resource disposal and implement IDisposable — The 'using' statement ensures that Dispose() is called on objects implementing IDisposable, preventing resource leaks. Importing namespaces is a different use of 'using'.

Answer

A. To import namespaces

Answer

C. To declare variables

Answer

D. To create aliases for types

Question 8

What will be the result of: string text = null; Console.WriteLine(text ?? "Default");

Accepted Answer

Correct answer: B. Default — The null-coalescing operator (??) returns the right operand if the left is null. Since text is null, it prints 'Default'.

Answer

A. null

Answer

C. NullReferenceException

Answer

D. Empty string

C# Programming - MCQ Practice Questions