C# Variable MCQs

Question 1: Which of the following methods is an entry point in the C# console program?

Answer: A,B,D

The execution of the C# console application starts from the method Main() method that can have one of the following signatures:

static void Main() {…}
static void Main(string[] args) {…}
static int Main() {…}
static int Main(string[] args) {…}

So, static void Main() is the entry point of the C# console program where access modifiers don't make any difference. However, the method name is case sensitive, so the main()(in lower case) is not an entry point. Learn to create C# Console Application.

Question 2: Which of the following keyword is used to include a different namespace in a program?

Answer: C

Write the using statement at the top to include the particular namespace into your program so that you can directly use its classes in your program. For example, write using System.Collections at the top of the .cs file in order to use any collection class in your program without writing a full namespace name every time. Suppose you do not include using System.Collections then you have to write the fully qualified class name System.Collections.ArrayList each time when you create an object of the ArrayList. Learn C# Collections.

Question 3: What will be the output of the following program? 

public static void Main()
{ 
    int a; 
    Console.WriteLine(a); 
}

Answer: C

You must assign a value to a variable before using it unless it is passed as an out parameter. The out parameter must be assigned to value before control leaves the method.

Question 4: What will be the output of the following code?

int i = 10, j;
Console.WriteLine(j=i*2);

Answer: C

Here, the result of the multiplication i*2 would be assign to j and Console.WriteLine() would print the value of j.

Question 5: What will be the output of the following program?

int i;
int j = i;
Console.WriteLine(j);

Answer: C

A variable must be assigned a value before using it. Here, i declared but not initialized, so the compiler will give an error "Use of unassigned local variable i".

Question 6: What will be the output of the following program?

public class Program
{
	public static void Main()
	{
		Employee emp = new Employee();
		Console.WriteLine(emp.salary); 
	}
}

public class Employee
{
	public int salary;
}

Answer: B

Static variables, instance variables, and array elements are automatically initialized to their default values. The default value of int is 0, so emp.salary is 0. Learn C# variables.

Question 7: What will be the output of the following program?

public class Program
{
	public static void Main()
	{
		int[] arr = new int[5];
		Console.WriteLine(arr[0]); 
	}
}

Answer: B

Static variables, Instance variables of class instances, and array elements are automatically initialized to their default values. The default value of int is 0, so all the elements in an integer array would be 0 by default. Learn C# variables.

Question 8: What will be the output of the following program? 

public static void Main()
{
	int k;
	display(k);
}
	
static void display(int val)
{
	Console.Write(val);
}

Answer: C

The variable must be initialized before accessing it or passing it to a function, otherwise the compiler would give an error. Learn C# variables.

Question 9: Which of the following keyword is used to declare a variable whose type will be automatically determined by the compiler?

Answer: B

Variables declared using var is called Implicitly Typed Variable. The C# compiler will determine its type at compile-time based on the value assigned to it.

Question 10: Which of the following type escapes type checking at compile-time; instead, it resolves type at run time?

Answer: A

The C# compiler does not check for the type of a dynamic variable. The type of a dynamic variable will be determined at the runtime based on the value it holds at runtime. It can hold any type of value at run time and not tied up to the specific data type.