C# Programming — MCQ Practice Questions & Answers

Question 1

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

Accepted Answer

Correct answer: B. 6 6 — ++x is pre-increment. It increments x first (x becomes 6), then assigns the value to y. So both x and y are 6.

Answer

A. 5 5

Answer

C. 5 6

Answer

D. 6 5

Question 2

Which of the following data types in C# is a value type?

Accepted Answer

Correct answer: B. int — int is a value type (primitive type). string, object, and arrays are reference types in C#.

Answer

A. string

Answer

C. object

Answer

D. array

Question 3

What is the correct way to declare a constant variable in C#?

Accepted Answer

Correct answer: A. const int MAX = 100; — The 'const' keyword is used to declare constants in C#. 'final' is Java syntax. While 'readonly' can be used, 'const' is the proper keyword for compile-time constants.

Answer

B. final int MAX = 100;

Answer

C. static int MAX = 100;

Answer

D. readonly int MAX = 100;

Question 4

What is the difference between '==' and 'Equals()' when comparing strings in C#?

Accepted Answer

Correct answer: A. '==' compares references, Equals() compares values — For strings, '==' compares references (memory addresses) while Equals() compares the actual string values. However, C# has optimized string comparison, so both often behave similarly for string literals.

Answer

B. '==' compares values, Equals() compares references

Answer

C. Both do the same thing

Answer

D. '==' is for primitive types, Equals() is for objects

Question 5

Which of the following will correctly convert a string to an integer in C#?

Accepted Answer

Correct answer: B. int x = int.Parse("123"); — int.Parse() converts a string to an integer. Direct casting doesn't work for strings. Convert.ToInt32() would throw an exception if the string is not a valid number. The 'as' operator doesn't work for strings to primitives.

Answer

A. int x = (int)"123";

Answer

C. int x = Convert.ToInt32("abc");

Answer

D. int x = "123" as int;

Question 6

Which of the following correctly declares a nullable integer in C#?

Accepted Answer

Correct answer: A. int? x = null; — In C#, 'int?' is used to declare a nullable integer. A regular 'int' cannot be assigned null. int* is a pointer (unsafe code), not a nullable type.

Answer

B. int x = null;

Answer

C. nullable int x = null;

Answer

D. int* x = null;

Question 7

What is the output of the following code? bool result = (5 > 3) && (2 < 1); Console.WriteLine(result);

Accepted Answer

Correct answer: B. false — (5 > 3) is true, but (2 < 1) is false. The '&&' (AND) operator returns true only if both conditions are true. Since one is false, the result is false.

Answer

A. true

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C. Error

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D. null

Question 8

Which keyword is used to prevent a class from being inherited in C#?

Accepted Answer

Correct answer: B. sealed — 'sealed' keyword prevents a class from being inherited in C#. 'final' is Java syntax. 'abstract' requires a class to be inherited. 'static' makes members class-level, not related to inheritance.

Answer

A. final

Answer

C. abstract

Answer

D. static

C# Programming - MCQ Practice Questions