Part 1 - C# Tutorial - Introduction.avi Video Lecture | C sharp: Enhance your Skills (English) - Back-End Programming

hi welcome to prism technologies my name
is Venkat this is part 1 introduction to
c-sharp in this module we will
understand the basic structure of the
c-sharp program what is a names based
focus on the main method with that let's
jump straight into a demo fire up Visual
Studio go to all programs Microsoft
Visual Studio 2010 Microsoft Visual
Studio 2010 this fires up Visual Studio
now create a new project go to file new
project and remember with not net we can
use a variety of different programming
languages like C sharp and there are
other programming languages as well
Visual Basic C++ F sharp now we will
choose a programming language as C sharp
and with.net you can create different
types of applications you can create web
applications windows applications of
this application shape or WCF etc but we
will be creating a console application
so the type of application is consumable
application and the programming
languages we should see sharp we will
name a project as introduction to
c-sharp and we are going to create that
project and C Drive click OK so this
creates a seizure control project for us
now we will be talking about solution
Explorer properties window toolbox etc
in a later session so let's close them
from now and I wouldn't make this
program as simple as possible so let's
leave only the basic required you know
lines of code within this program and
get rid of the others so let me get rid
of this unwanted namespace declarations
I also don't require their slime this
one and I don't even require these
parameters to the main method
right so if you look at this particular
program it's a very simple program
hardly three lines is called couple of
places around it okay now what do we
want this program to do I want this
program to print a very simple message
onto a console screen if you're
wondering what is a console screen it's
nothing but the command prompt window
and to get to the command prompt window
start run and type CMD or C um a and E
okay anything would get you to the
command prompt so this is the command
okay so on a window like this
I want a message welcome to see you
should have training and I want you
seizure program to do that and to do
that it's very simple okay I don't have
to write any new methods or something
like that I can make use of the classes
that are present inside it or not
framework now if you're new to what is
not a framework that please check you
know my video tutorial on net framework
basics okay so with internet framework
we have a class called console class
okay we can use this console class
basically to write or read messages from
the console window if we use a has type
something into that okay so now my
program has to write something so I'm
going to use a function called write
line okay so I'm using this red line
function and to that I will pass a
message that I want to be printed on to
the console for example I want this
message will come to C sharp training to
be printed on to the message and now to
run this program all I have to do is
press ctrl f5 and once you do that you
have that message on the screen
welcome to C sharp training press any
key to continue and I do that the
program terminates okay so it's as
simple as that so if I have to print a
message all you have to do is use the
straight line method pass it the message
that you want to plant it and this
function is present inside this class
now if you look at this program
a couple of pieces involved in this okay
the first line right here is called the
namespace declaration okay so what do we
mean by namespace declaration basically
this line tells that to the rest of the
program we are going to make use of code
that is present inside this system
namespace okay so what is the namespace
I mean element understand that a
namespace is a collection of classes for
example okay because this control class
if you look at the fully qualified name
of that this comes on glass full name is
actually system so the control class is
present inside the system namespace so
if I hover over that it says namespace
system so this control class is present
inside this namespace if I don't have
this declaration there what's going to
happen look at this we get an error okay
so what is that the name console does
not exist in the current context okay so
this red squiggly line indicates it's an
error so if I try to build this
application if I go to the build menu
and say spill solution I get a compiler
error the name does not exist the
current context that's because the
program does not know where is this
coming from
so to let our program know that we are
going to making classes that are present
inside the system namespace we use the
Declaration call using system like so so
this will tell to program you know we
are going to make use of that class
control class which is present inside
this namespace if you ask me either
namespace just a collection of classes
no it's a collection of variety of
things for example let me take you to
the slide so in this slide you can see
that a namespace is basically used to
organize you cool and it's a collection
of classes interfaces structures enums
and delegates now what are these okay so
we will be talking about classes
interfaces structures enhance and
delegates in a very great detail in a
later video sessions so until then don't
worry so
but just understand that a namespace is
basically used to organize your code and
it's a collection on these okay so
that's that now just to show you it's in
fact is a collection of all that system
dot look at this for example action
that's a delegate so a namespace can
contain delegates and if you look at
this one activator that's a class and
similarly there are various other things
like events etc and if you look at this
interestingly this one is actually a
namespace so a namespace can contain
other names basis as well so what is the
namespace a namespace is used to
organize your code and it's a collection
of classes delegates namespaces etc okay
now is it mandatory for me you for me to
use a declaration like this no not
really you can get rid of that if you
want but if you do that you have to use
the fully qualified name like so so you
can either use the fully qualified name
like that or you can use the namespace
declaration it's up to you whichever is
convenient usually in general people use
namespace declaration at the top because
if a new program if you are referring to
control class multiple times you don't
have to use the system keyword you know
every time you use the class if you have
a namespace declaration here so that
makes it more easy let's type in
basically okay alright so that's about
namespace declaration another important
thing to understand here so let's get
rid of this let's have another namespace
declaration using system and then
the next piece of thing that you have to
understand is this class class program
okay so any piece of school that you
write to actually be inside a class and
talk about classes there are static
classes and instance classes which we'll
be talking about in a very great detail
in a later session so until then don't
worry we just require a class any piece
of code that we write shouldn't be
residing inside a class so this function
should have a place to live and that is
when this class program okay and this
method this is the function functions
and methods are the one which will
actually do the work functions in a very
great detail again in a later session a
function will have something relaxed
modifiers static modifiers written types
function names and parameters so we'll
be talking about all these in a later
session but if you look at right here
this function name is called as main
function so basically this function
tells okay the program execution when I
actually run the program the execution
should start right there and end right
there so if I run this program what's
going to happen it enters you know it
starts executing here prints this line
and terminates here okay now let's say
let me make a copy of this say for
example I have you know maybe I'll call
that main one and just for
differentiation we call this as training
one now if I execute this program do you
think we'll this message be printed or
this message will be printed or both of
them will be printed what do you think
will happen you know from this slide if
you understand main method is the entry
point your application so where is the
main method this one is the main method
this is not the main method because it
says main one so it treats that method
as something else so this is the entry
point so you program execution starts
here and here which means it only will
print this line it
the slide okay so if you're a class you
know you have this classical program if
this class has got hundreds of methods
inside that now which way should your
control application starts it started in
execution that's what is determined by
your main method so your main method is
basically the entry point in your
application okay now so let's go ahead
and run this the moment I run that look
at this it says welcome to see shop
training which is this one but it
doesn't print the line but what if I
want even that line to be printed and
the way to do it is just before you know
we know that the program will be
terminated here just before that call
your main function as well so what
happens when we run the program the
execution starts here it prints this
line and then says since this method
call this function call all right
that way I need to call this function as
well so it goes here it executes this
function
finishes the call come back into this
line and so now if I go ahead and run
this program
it's going to print both of these
messages so it's as simple as that but
one thing to keep in mind is that every
control application should have a main
method which basically tells that's the
entry point that's where the program
should start executing okay so to sum up
this is simple seizure program you know
we have a namespace declaration and we
need to have class and inside that class
we have our main method which signifies
the entry point into your application
and we are printing using system
declaration the namespace declaration
indicates that you use system namespace
and hence this is basically used
organizing cool and it's a collection of
classes interfaces structures in and
some delegates and main method is the
head your application so that's it in
this presentation for additional
resources please check our website at
present a comm and for any interview
question say at an c-sharp please
these two resources thank you for
listening have a great day