1. What is C#?
C# is a new object-oriented language from Microsoft that is
currently used for application development on the .NET platform. It exhibits features found in languages
such as C++, Java, Smalltalk, and Perl, among others.
C# has been submitted to the standards
body.
C# can inter operate exceptionally
well, with different languages in the .Net platform.
C# is fully object oriented programming language to
develop dynamic web applications in .net frame work.
C# is an object oriented and user friendly. It gives security and re
usability.
We can develop multiple applications.
2. What is the difference between abstract classes and interface?
Abstract
classes
|
Interface
|
|
1.
|
Can contain
declaration & also implementation
|
Class can
contain only declaration
|
2.
|
A class may
inherit only abstract class.
|
A class may
inherit several interfaces.
|
3. |
An abstract
class provides complete, default code or just the details that have to be
override.
|
An interface
cannot provide any code just the signature.
|
4.What is a delegate?
Delegate
is a class that can hold a reference to a method or a function. Delegate class
has a signature
and it
can only reference those methods whose signature is compliant with the
class.
Delegates
is a function pointer like in C.Which holds the references of the method.
It
has two type
1.Single
2.
Multicast.
5.What is the difference between convert.to.string and .to. string() method?
Convert function handles nulls while i.string() does not it will throw a null reference exception error.
6.What is the difference between const and static readonly?
The
difference is that static read-only can be modified by the containing class,
but const can never be
modified
and must be initialized to a compile time constant. To expand on the static
read-only case a
bit,
the containing class can only modify it:
- in
the variable declaration (through a variable initializer)
- in
the static constructor (instance constructors if it's not static).
7.What is an Indexer?
An
indexer is a member that enables an object to be indexed in the same way as an
array.
8.What is difference between constants, readonly and, static ?
Constants : The value can't be changed.
Read-only : The value will be initialized only once from the constructor of
the class.
Static :
Value can be initialized once.
9.What is a static constructor?
A
constructor for a class, rather than instances of a class. The static
constructor is called when the class
is loaded.
Static
constructor does not contain parameters. class contain only one static
constructors.
Constructor
has same name of class. if class name is ‘a’ than it should necessary the
constructor name
is also
‘a’'.
10.What is a Class?
A class describes all the attributes of objects as well as the methods that
implements the behavior of
member objects.
Class
is collection of an object. It is a blueprint that describes the
details(characteristics and
behaviour)of
an object for e.g
Bird is a class.
Kingfisher,
Peacock, Sparrow are all birds. They all lay eggs,covered with feather, have
ability to fly so
they
share common characteristics and features and belong to the class called bird.
Class
is a collection object. Class is a collection of data member & member
function. Class has no existance.
11.What are the different accessibility levels defined in .NET?
There
are Five levels of Access Modifiers are :
Private
Protected
Friend
Protected Friend
Public
1.private
2.protected 3.internal 4.protected internal 5.public these access modifiers are
used in c#.net
friend
access modifier is used in vb.net
12.Can I use exceptions in C#?
Yes, in
fact exceptions are the recommended error-handling mechanism in C# (and in .NET
in general).
Most of
the .NET framework classes use exceptions to signal errors.
13.Can we have shared events?
Yes,
you can have shared events note only shared methods can raise shared events.
14.What are the namespaces used in C#.NET?
A namespace is
designed for providing a way to keep one set of names separate from another.
The
class
names declared in one namespace will not conflict with the same class names
declared in another.
using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.Serialization;
using System.ServiceModel;
using System.Text;
using System.Web;
using System.ServiceModel.Web;
using System.Data.SqlClient;
using
system.configuration;
using
system.io;
15.What are the two data types available in C#?
Value type
Reference type
16.What is Array List?
Array List can hold item of different types. As array list can increase and
decrease size dynamically you
do not have to use the REDIM
keyword. You can access any item in array using INDEX value of the array position.
17.How is method overriding different from overloading?
When overriding, you change the method behavior for a derived class. Overloading simply involves having a method with the same name within the class.
18.What is hash table?
Hash
table provides way of accessing the index using a user identified KEY value,
thus removing the INDEX
problem.
19.What are the similarities between class and structures?
Both can have constructors, methods, properties, fields,
constants, enumeration, events and event handlers.
Structures and classes can implement interface.
Both can have delegates and events.
Both of them can have constructors with and without parameter.
20.Does C# have copy constructors?
No.
Objects in C# are always created by reference rather than by value, so a copy
constructor is never
implicitly called the way that it might be in C++.