Part 49 C# Tutorial Access Modifiers in C# Video Lecture - C sharp Enhance

hello welcome to prism technologies I am
venket this is pad 49 access modifiers
in this session we'll talk about
different access modifiers that can be
applied for pipe members for types
themselves you can only apply to
different access modifiers which we will
be talking about in a later session in
this session we will also talk about
private public and protected members in
a great detail and in the next session
we'll be talking about the other two
access modifiers internal and protected
internal and to understand this session
properly it's better if you have a good
understanding of the difference between
types and type members all right in
c-sharp there are actually five
different access modifiers private
protector internal protected internal
and public in this session as I told you
we'll be talking about the first three
actually private protected and public in
the next session we'll talk about
internal and protected internal okay
so private members are available only
within the containing type whereas
public members are available anywhere
and there is no restriction on public
members so let's see what do we mean by
this and it's very simple to understand
okay let's have a customer class so
public class customer and this class is
going to have a private indeed you feel
so private and underscore ID is my cusp
private feel I'm going to create a
public property so public and ID and you
know to expose that property we can use
a ket and a set accessor so return
underscore ID and we will set and just
cry D to the value and by the way if you
if you don't know what properties are we
have a video recorded on properties
please check that video all right now if
you look at this customer class is
pretty simple they've got one private
field underscore ID and one public field
ID okay
now since this
this field is private this is available
only within the containing type so
what's the containing type for this file
this class customer okay so this field
is available only within this customer
class look at this I'm able to access
this here and I'm able to return that
and I'm able to set a value for that
okay but only within this type if I try
to access this field outside of this
class I will get a compiler error let's
see now how we do that now outside of
this class so in the main class I have
another class here also in the main
class I have a main method and in this
main method I am creating an instance of
this customer class so customer c1 is
equal to new customer and now since this
field is an instance field again we have
a video recorded you know on the
difference between static and instance
field if you're not sure what what do we
mean by static and instance fields
please check that video series so since
this ID is an instance field you know
you can access that on the instance of
the class so I'm creating this customer
class instance c1 and if I try to access
c1 dot look at this do I see the
underscore ID in the intellisense I
don't okay so this is actually a hint to
you you're not allowed to access that
but if I try to access that by just
typing the name
maybe I'm trying to print that let's say
you can see a red that's Quigley already
there it says customer dot underscore ID
is an accessibility reach protection
level so because of the X is modifier
you have there it's inaccessible okay
it's private so that field is available
only within that customer class outside
of the customer class it's not available
so that's private if you try to access
that you will get a compiler error
inaccessible due to its production level
on the other hand this ID fee property
is actually public so public it is
accessible anywhere no restrictions
whatsoever within the class outside of
the class even in a different assembly
we'll talk about different accessing
members from different assemblies in a
later session but public member is
basically available anywhere there is no
restriction whatsoever so if I try to
print and I say C dot ID look at that I
am able to access that and if I try to
build this I will get no compiler errors
so on the status bar if you get that
will succeed it so very simple and
straight if you look at this slide here
private members-only within the
containing class what is the
accessibility only within the containing
class whereas public member anywhere no
restrictions so if you look at this five
different access modifiers private and
our members will have least restriction
I mean highest restriction it's only
available within the class containing
class whereas public there is no
restrictions so these two are the two
extreme ends and protected internal
protected internal falls in between them
which we'll be talking about now in a
bed all right so public anywhere no
restrictions now let's go ahead and look
at protected access modifier what do we
mean by protected access modifier and
what access level does it have and to
understand that let's create a simple
class okay we already have this customer
class and if you
this customer class what we will do is
we will create a protected may be
protected end and I'm saying ID okay so
within this class this ID field is
protected so if I feel I mean if a
member is protected then that member is
available within the containing class
and to any class that derives from the
containing class okay now if you look at
this is main class deriving from the
containing class know so obviously this
ID will not be available here look at
that you already have a red squiggly
customer dot ID is inaccessible duty
it's protection level but on the other
hand let's create another class so
public basically my customers are of two
types may be corporate customers and
retail customers so customer is the base
class for every type of customer in my
business okay so I'm going to have
another customer call let's say
corporate customer and this class is
going to inherit from the customer class
okay now corporate customer inheriting
from customer class and we know that a
protected member you know it's available
protected members are available within
the containing type or class and do the
types or classes that derive from the
containing type okay so since our
corporate customer class is deriving
from the customer class you can access
this protected member but on the other
hand your main class is not deriving
from your customer class so you have
that let's quickly there a compiler
error of showing ID is inaccessible due
to its production level okay now let's
say I'm going to have a method here
maybe public void print ID and now let's
create a corporate customer object so
corporate customer CC is equal to new
corporate customer since this field is
an instance field we need to create an
instance of the derived class object and
then CC dot look at this ID I am able to
access that okay and maybe I can set it
a value of 1 0 1 if I wish to okay so
protected members are available within
the containing class and to the classes
that derive from the containing class if
a class doesn't derive from the
containing class then that protected
member will not be available to that
class that's why you're maint loss is
not able to access that ID and by the
way to access protected members know
plexus the base class protected members
in the derived class you can either use
the derived class object your corporate
customer class is deriving from the
customer class so we create an instance
of that class and on that instance we
are invoking that feel ok now instead of
doing this what you can also do is you
can basically use base keyword base dot
look at this ID base in the derived
class method actually refers to base
class instance so that's that's why you
are able to access that property
dot ID or simply you can use this
keyword as well this dot ID will also
give access to it okay so basically if
you want to access base class protected
members in the derived class you can
either use the derived class object or
you can use the disk keyword or you can
use the base keyword but if you try to
do any of that in a class that doesn't
inherit from the base customer class
here in this example you get
accessibility error okay
so here you can't even say base dot base
dot you cannot use any you know you
cannot basically invoke the ID here
because why there is no base class for
this this class is a standalone class
it's not the inheriting from any of the
base class okay so that's about
protected so if you look at productive
members they're available within the
containing type and to the types that
derive from the containing type and in
the next session we'll be talking about
internal and protected internal on this
slide you can find resources for asp.net
and C sharp interview questions that's
it for today thank you for listening
having