C# Questions & Answers on Method Overriding for Freshers
https://www.computersprofessor.com/2018/06/c-questions-answers-on-method_27.html
1. Which keyword is used to declare a base class method while performing overidding of base class methods?
a) this
b) virtual
c) override
d) extend
Answer: b
2. The process of defining a method in subclass having same name & type signature as a method in its superclass is known as?
a) Method overloading
b) Method overriding
c) Method hiding
d) None of the mentioned
Answer: b
3. Which of the given modifiers can be used to prevent Method overriding?
a) Static
b) Constant
c) Sealed
d) final
Answer: c
Explanation: When an instance method declaration includes sealed modifier,the method is said to be sealed method.It means a derived class cannot override this method.
4. Select the correct statement from the following?
a) Static methods can be a virtual method
b) Abstract methods can be a virtual method
c) When overriding a method, the names and type signatures of the override method must be the same as the virtual method that is being overriden
d) We can override virtual as well as non virtual methods
Answer: c
5. Which of the following cannot be used to declare a class as a virtual?
a) Methods
b) Properties
c) Events
d) Fields
Answer: d
6. What will be the output for the given set of code?
class A{public int i;
public void display()
{Console.WriteLine(i);
}}class B: A
{public int j;
public void display()
{Console.WriteLine(j);
}}class Program{static void Main(string[] args)
{B obj = new B();
obj.i = 1;
obj.j = 2;
obj.display();
Console.ReadLine();
}}
a) 0
b) 2
c) 1
d) Compile time error
b) 2
c) 1
d) Compile time error
Answer: b
Explanation: When method display() is called using objects of class ‘B’. The method ‘display()’ for class ‘B’ is called instead of class ‘A’ as class ‘B’ is inherited by class ‘A’.
Output :2
7. What will be the output for the given set of code?
class A{public virtual void display()
{Console.WriteLine("A");
}}class B: A
{public override void display()
{Console.WriteLine(" B ");
}}class Program{static void Main(string[] args)
{A obj1 = new A();
B obj2 = new B();
A r;r = obj1;
r.display();
r = obj2;
r.display();
Console.ReadLine();
}}
a) A, A
b) B, B
c) Compile time error
d) A, B
b) B, B
c) Compile time error
d) A, B
Answer: d
Explanation: The method overidding procedure has been used to produce the values from two display().
Output : A B
8. The modifier used to hide the base class methods is ?
a) Virtual
b) New
c) Override
d) Sealed
Answer: b
Explanation: Used in condition when we cannot use virtual to override a base class method. Hence, we use ‘New’ to hide the base class methods and redefine the method defined in sub class.
9. To override a method in subclass, baseclass method should be defined as?
a) Virtual
b) Abstract
c) Override
d) All of the mentioned.
Answer: d
10. What will be the output for the given set of code?
class a{public void fun()
{Console.WriteLine("base method");
}}class b: a
{public new void fun()
{Console.WriteLine(" derived method ");
}}class Program{static void Main(string[] args)
{b k = new b();
k.fun();
Console.ReadLine();
}}
a) Base method
b) Derived method
c) Code runs successfully prints nothing
d) Compile time error
b) Derived method
c) Code runs successfully prints nothing
d) Compile time error
Answer: b
Explanation: Use of ‘new’ modifier hides the inherited member i.e it makes only inherited member inaccessible in derived class and hence calls suitable method().
Output :derived method
