C#.NET Interview QA
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| C#.NET |
1. What is C#?
C# (pronounced "C sharp") is a simple, modern,
object-oriented, and type-safe programming language. It will immediately be
familiar to C and C++ programmers. C# combines the high productivity of
Rapid Application Development (RAD) languages.
2. What are the types of comment in C#?
There are 3 types of comments in C#.
Single line (//)
Multi (/* */)
Page/XML Comments (///).
3. What are the namespaces used in C#.NET?
Namespace is a logical grouping of class.
using System;
using System.Collections.Generic;
using System.Windows.Forms;
4. What are the characteristics of C#?
There are several characteristics of C# are :
Simple
Type safe
Flexible
Object oriented
Compatible
Consistent
Interoperable
Modern
5. What are the different categories of inheritance?
Inheritance in Object Oriented Programming is of four types:
Single inheritance: Contains one base class and one derived
class.
Hierarchical inheritance: Contains one base class and multiple
derived classes of the same base class.
Multilevel inheritance: Contains a class derived from a derived
class.
Multiple inheritance: Contains several base classes and a
derived class.
6. What are the basic concepts of object oriented programming?
It is necessary to understand some of the concepts used
extensively in object oriented programming.These include:
Objects
Classes
Data abstraction and encapsulation
Inheritance
Polymorphism
Dynamic Binding
Message passing.
7. Can you inherit multiple interfaces?
Yes. Multiple interfaces may be inherited in C#.
8. What is inheritance?
Inheritance is deriving the new class from the already existing
one.
9. What is scope?
Scope refers to the region of code in which a variable may be
accessed.
10. Difference between public, static and void?
public: The keyword public is an access modifier that tells the C#
compiler that the Main method is accessible by anyone.
static: The keyword static declares that the Main method is a global one
and can be called without creating an instance of the class. The compiler
stores the address of the method as the entry point and uses this information
to begin execution before any objects are created.
void: The keyword void is a type modifier that states that the
Main method does not return any value.
11. Modifiers in C#?
Abstract
Sealed
Virtual
Const
Event
Extern
Override
Readonly
Static
New
12. What are the types of access modifiers in C#?
Access modifiers in C# are :
public
protect
private
internal
internal protect
13. What is boxing and unboxing?
Implicit conversion of value type to reference type of a
variable is known as BOXING, for example integer to object type
conversion.
Conversion of reference type variable back to value type is
called as UnBoxing.
14. What is object?
An object is an instance of a class. An object is created by
using operator new. A class that creates an object in memory will
contain the information about the values and behaviors (or
methods) of that specific object.
15. Where are the types of arrays in C#?
Single-Dimensional
Multidimensional
Jagged arrays.
16. What is the difference between Object and Instance?
An instance of a user-defined type is called an object. We can
instantiate many objects from one class.
An object is an instance of a class.
17. Define destructors?
A destructor is called for a class object when that object
passes out of scope or is explicitly deleted.A destructors as the name
implies is used to destroy the objects that have been created by a constructors.Like
a constructor , the destructor is a member function whose name is the same
as the class name but is precised by a tilde.
18. What is the use of enumerated data type?
An enumerated data type is another user defined type which
provides a way for attaching names to numbers thereby
increasing comprehensibility of the code. The enum keyword automatically
enumerates a list of words by assigning them values 0,1,2, and so on.
19. Define Constructors?
A constructor is a member function with the same name as its
class. The constructor is invoked whenever an object of its
associated class is created.It is called constructor because it constructs
the values of data members of the class.
20. What is encapsulation?
The wrapping up of data and functions into a single unit (called
class) is known as encapsulation. Encapsulation containing and
hiding information about an object, such as internal data structures and
code.
21.Does c# support multiple inheritance?
No,its impossible which accepts multi level inheritance.
22. What is ENUM?
Enum are used to define constants.
23. What is a data set?
A DataSet is an in memory representation of data loaded from any
data source.
24. What is the difference between private and public keyword?
Private: The private keyword is the default access level and most
restrictive among all other access levels. It gives least permission to a
type or type member. A private member is accessible only within the body of the
class in which it is declared.
Public: The public keyword is most liberal among all access levels, with
no restrictions to access what so ever. A public member is accessible not
only from within, but also from outside, and gives free access to any member
declared within the body or outside the body.
25. Define polymorphism?
Polymorphism means one name, multiple forms. It allows us to
have more than one function with the same name in a program. It allows us
to have overloading of operators so that an operation can exhibit
different behaviors in different instances.
