C# MCQs with Answers | C Sharp and .NET Questions – Page 4

Question 61 C#

What is the output of: static void Inc(ref int a) => a++; int v = 1; Inc(ref v); Console.WriteLine(v);?

Correct answer D. 2

Open question

Question 62 C#

What rule applies to an out parameter in C#?

Correct answer B. The method must assign it before returning; the caller need not initialise it

Open question

Question 63 C#

What does the in modifier on a C# method parameter mean?

Correct answer B. The argument is passed by reference but cannot be modified by the method

Open question

Question 64 C#

Given static int Sum(params int n) => n.Length;, what does Sum() return?

Correct answer B. 0

Open question

Question 65 C#

Which rule applies to optional parameters in C#?

Correct answer D. They must come after all required parameters and have compile-time constant defaults

Open question

Question 66 C#

Given static void Show(int a, int b), which call uses named arguments correctly in C#?

Correct answer C. Show(b: 2, a: 1)

Open question

Question 67 C#

Which pair of methods would NOT be valid overloads in the same C# class?

Correct answer C. int Get(int x) and string Get(int x)

Open question

Question 68 C#

What is the key difference between const and readonly fields in C#?

Correct answer B. const is fixed at compile time; readonly can be assigned at declaration or in a constructor

Open question

Question 69 C#

What happens when this C# code runs: int? n = null; int x = n.Value;?

Correct answer D. An InvalidOperationException is thrown

Open question

Question 70 C#

Which of these conversions in C# requires an explicit cast?

Correct answer B. double to int

Open question

Question 71 C#

What does Console.WriteLine(Math.Round(2.5)); print in C#?

Correct answer A. 2

Open question

Question 72 C#

In C#, what is boxing?

Correct answer B. Converting a value type to object or an interface type, which copies it into a heap object

Open question

Question 73 C#

What happens when this C# code runs: object o = 5; long n = (long)o;?

Correct answer A. An InvalidCastException is thrown

Open question

Question 74 C#

What is the output of: string s = “abc”; s.ToUpper(); Console.WriteLine(s);?

Correct answer C. abc in small letters

Open question

Question 75 C#

Which statement about the var keyword in C# is true?

Correct answer B. The type is inferred at compile time and the variable stays strongly typed

Open question

Question 76 C#

How does dynamic differ from var in C#?

Correct answer B. dynamic defers member binding and type checking to run time, while var is resolved at compile time

Open question

Question 77 C#

What does Console.WriteLine(“5” + 3 + 2); print in C#?

Correct answer A. 532

Open question

Question 78 C#

What does Console.WriteLine(7 / 2); print in C#?

Correct answer B. 3

Open question

Question 79 C#

What does Console.WriteLine(-7 % 3); print in C#?

Correct answer B. -1

Open question

Question 80 C#

What is the output of: int x = 5; Console.WriteLine(x++ + ++x);?

Correct answer D. 12

Open question