Method Overriding - C# Questions & Answers

This section of our 1000+ C# multiple choice questions focuses on method overriding in C# Programming Language.

1. Which keyword is used to declare a base class method while performing overriding of base class methods?
a) this
b) virtual
c) override
d) extend
View Answer

Answer: b
Explanation: None.

2. The process of defining a method in a 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
View Answer

Answer: b
Explanation: None.

3. Which of the given modifiers can be used to prevent Method overriding?
a) Static
b) Constant
c) Sealed
d) final
View Answer

Answer: c
Explanation: When an instance method declaration includes the 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 overridden
d) We can override virtual as well as nonvirtual methods
View Answer

Answer: c
Explanation: None.

5. Which of the following cannot be used to declare a class as a virtual?
a) Methods
b) Properties
c) Events
d) Fields
View Answer

Answer: d
Explanation: None.

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6. What will be the output of the following C# 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
View Answer

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 :

7. What will be the output of the following C# 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
View Answer

Answer: d
Explanation: The method overriding 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
View Answer

Answer: b
Explanation: Used in condition when we cannot use virtually to override a base class method. Hence, we use ‘New’ to hide the base class methods and redefine the method defined in the subclass.

9. To override a method in the subclass, the base class method should be defined as?
a) Virtual
b) Abstract
c) Override
d) All of the mentioned
View Answer

Answer: d
Explanation: None.

10. What will be the output of the following C# 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
View Answer

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

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