Class

Question 1

What is a constructor?

Answer 1

It is a special type of function which is used when initialization of an object. It does not return any value.
Having a construct is an optional.

Question 2

What are object initializers?

Answer 2

Object initializers is the easiest and fastest way to assign values of an object’s properties and fields. An object can be initialized without explicitly calling a class’s constructor.

consider a class

class Person{
   public int year;
   public string name;
   public string country;

 /*  public Person(name)
   {
      this.name = name;
    }

   public Person(name, country)
   {
       this.name = name;
       this.country = country;
   } */
}

The list of constructors will grow. Henc, using object initializers, we can avoid multiple constructor.

     var Person = new Person
            {
                year = 1986,

            name = "bharth",

            country = "canada"

        };

Question 3

What is params keyword?

Answer 3

By using params keyword we can pass multiple numbers of arguments to a function.

public int Add(params int[] numbers)
        {
            int ret = 0;
            foreach(var num in numbers)
            {
                ret += num;
            }

        return ret;
    }

Console.WriteLine(person.Add(1,8, 5, 7, 8, 5));

Question 4

how many access modifiers available?

Answer 4

public private protected internal ProtectedInternal

Question 5

code snippet for adding a ne properties

Answer 5

prop + tab Tab

Question 6

What is the parent of all classes in .Net?

Answer 6

Object class

Question 7

What is Class Coupling

Answer 7

A measure of how interconnected classes and subsystems are.
- The more coupled classes, the harder it is to change them. A change in one class may
affect many other classes.
- Loosely coupled software, as opposed to tightly coupled software, is easier to change.
- Two types of relationships between classes: Inheritance and Composition.

Question 8

What is Inheritance?

Answer 8

• A kind of relationship between two classes that allows one to inherit code from the
  other.
• Referred to as Is-A relationship: A Car is a Vehicle
• Benefits: code re-use and polymorphic behaviour.
  public class Car : Vehicle
  {
  }

Question 9

why should we favor composition over inheritance?

Answer 9

Problems with inheritance:
• Easily abused by amateur designers / developers
• Leads to large complex hierarchies
• Such hierarchies are very fragile and a change may affect many classes
• Results in tight coupling

• Benefits of composition:
  • Flexible
  • Leads to loose coupling
• Having said all that, it doesn’t mean inheritance should be avoided at all times. In fact,
  it’s great to use inheritance when dealing with very stable classes on top of small
  hierarchies. As the hierarchy grows (or variations of classes increase), the hierarchy,
  however, becomes fragile. And that’s where composition can give you a better design

Question 10

Naming convention for private fields?

Answer 10

use _

Question 11

What is boxing?

Answer 11

The process of converting value type instance to an object type reference.

int number = 10;
object obj = number;

10 is stored in the heap.

int j = (int) obj

VR - > Boxing

This is moer of theory. In realworld, when we use ArrayList we are actually boxing it when we call add.
            var arrList = new ArrayList();

        arrList.Add(1);
        arrList.Add("list");

Although this provides flexibility, it affects performance.

Question 12

Realtime example og boxing?

Answer 12

var list = new ArrayList();

list.Add(object);

Add method accepts object.

list.Add(1) will box the value.

Question 13

If e create one of the meber as Private, how can we access the property?

Answer 13

Create a method called Get and Set***()

What is the use? The use is that members should not be easily accessible.

Question 14

How can we pass from one constructor to an another constructor?

Answer 14

using this..

Question 15

What is readonly keyword?

Answer 15

readonly increases the robustness of the code. It needs to be initialized either when we declare it or in the constructor. Once, initialized it cannot be changed.

Question 16

How to initlialzie a field?

Answer 16

A field can be initialized in two ways: In a constructor, or directly upon declaration. The
benefit of initialising a field during declaration is that if your class has one or more
constructors, you’ll make sure that the field will always be initialised irrespective of
which constructor is going to be called.