Part 51 C# Tutorial Access Modifiers for types Video Lecture - C sharp

hello welcome to presume technologies
I'm ranked it this is part 51 access
modifiers for types if you haven't
watched part 48 49 and 50 I would
strongly encourage you to do so before
continuing with this session in this
session we'll be learning about the
access modifiers that can be applied for
types themselves in the previous session
we have learned the different modifiers
that can be applied for type members now
we know that in c-sharp there are five
different access modifiers and from the
previous sessions we have already
understood all these five different
access modifiers can be applied for type
members but when it comes to types you
can only use public and internal access
modifiers with types trying to use any
other access modifier will generate a
compiler error let's look at an example
and in order to understand internal and
public access modifiers probably we need
to you know two assemblies okay so let's
add two class library projects to the
solution and to do that right click on
the solution add and select new project
select visual C sharp as your
programming language and let's select
class library as the project type I'm
going to name this as assembly one
project click OK that should create the
project let's add another project I'm
going to call this assembly two project
click okay and it should create another
project now with in assembly one in
class 1 dot CS file I'm going to create
a class called assembly 1 class and with
this class I'm gonna have a print method
so public void trend method and what
this method does it just prints a
message onto the console to control a
trade line
hello all right so if you look at this
code we have this class and this class
access modifier is public and from the
slide we understood that you know with
types you can only use internal or
public access modifiers what happens if
I use any other access modifiers for
example what happens if I use private
access modifier on the type if I do that
if I try to build the solution look at
what happens if we will get a compiler
error and look at the error
it says elements defined in a namespace
cannot be explicitly declared as private
protected or protected until now now
what do we mean by elements defined in a
namespace now what are the different
elements that can be defined within a
namespace we can define a class we can
define a structure we can define an
interface delegates etc so all these are
examples of types okay
so types can only have internal or
public access modifiers trying to use
any other access modifier will give you
a compiler error so if I convert this
back to public we will get no compiler
error so if I build as ctrl shift B
shortcut for building a solution on the
status bar you can see been succeeded so
you can use public access modifier now
what do we mean by public if you mark
him a type as public then obviously it
will be available anywhere no
restrictions whatsoever or
now let's try to access this class which
is present in assembly one
in assembly to project okay and
obviously to do that in assembly to
project we need to add a reference to
assembly one project okay and to do that
just open the reference is folder and
right-click on that and reference select
assembly one project from the list click
OK and you should see assembly one being
added there okay so now let's go to
class 1 dot CEA's file of assembly to
project get rid of this unnecessary
using statements which we don't use I'm
gonna call this class as assembly to
class so that the names will be clear so
within this assembly to class let's have
another method public void test and
within this method I'm going to create
an instance of this class assembly one
class and to do that assembly one can
you see that you see the namespace but
not the class so assembly one but
assembly one class you can either use
the fully qualified name or you can
actually use the using statement so
using assembly one so assembly one class
and let's call it as instance is equal
to new assembly one class and on the
instance I can invoke the print method
so now I am able to access the type that
is defined in assembly one in assembly
too okay why because that's public
that's accessible anywhere no
restrictions whatsoever so now if I
build the solution we get no compiler
errors so you see on the status bar
build succeeded ok now let's go back to
class one dot CSV file of assembly one
instead of public let's use internal
access modifier all I did here is change
the access modifier from public to
internal we know that if a member is
internal then it will be available only
in the containing assembly and the same
is the true even for types if you mark a
type
internal then that type is available
only with that assembly where it's
defined trying to access that type
outside of that assembly will generate a
compiler error now we are using this
assembly one class which is internal and
which is present in assembly one project
in assembly two and look at that we
already have that red squiggly lines
indicating you know some sort of error
okay so if I try to build a solution we
should get about four errors and all of
them look at that assembly one dot
assembly one class is inaccessible its
production level which is very clear
that you're not allowed to access that
particular class outside of assembly one
so any internal member or a type defined
as you know within an assembly can be
only accessed within that assembly
trying to access that outside of the
assembly will generate a compiler error
and to get rid of those errors all you
need to do is make it public since
public member is accessible anywhere if
I try to build this now all those errors
should have gone and build such see
there now let's do another thing let's
delete the excess modifier altogether
now I am not having any access modifier
whatsoever so then what is going to be
the access modifier now four types if
you don't specify an access modifier the
default will be internal okay so if I
build the solution now we again get
those four errors because why if you
don't specify the access modifier four
types the default will be internal but
on the other hand if you don't specify
an access modifier for a type member
then it will be private in fact this is
actually an interview question they will
ask you in general in an interview okay
what is the default access modifier a
type member in private what is the
default access modifier for types if you
don't specify one internal ok so just
keep in mind type members can have all
of the access modifiers
whereas types can only have two access
modifiers for type members if you don't
specify an access modifier the default
will be private
so types if you don't specify an access
modifier the default will be internal I
can see that on this slide so private is
the default for type members
whereas intima is the default for types
okay and if you're not sure about the
other access modifiers you know private
protected and protected into now we have
already covered that in the previous
session so please do check that session
all right on this slide you can find
some resources for asp.net and C sharp
interview questions that's it for today
thank you for listening have a great day