Part 10 - C# Tutorial - If statement in C# Video Lecture - C sharp Enhance

hello welcome to presume technologies
I'm ranked it this is part 10 if
statement and c-sharp if statement is
actually a conditional statement and
c-sharp there are two types of
conditional statements if statement and
switch statement in this session we'll
talk about a statement in the next
module we'll talk about switch statement
so in this session we'll be learning
about if statement if else statement and
the difference between double ampersand
and its count about single ampersand and
the difference between double pipe and a
single pipe let's look at the demo now
to understand the if statement let's
write a simple C char program I want the
user to enter a number and I want to
decide okay is the number one two or
three using a simple if statement okay
so first I need to prompt the user to
enter his number and to do that console
dot write line so from the user to enter
his number so please enter a number so
the user now will enter a number we need
to read that from the console so console
dot readline and if you observe read
line method reads the entered number in
the string format okay now once we read
the number from the console we need to
assign it to an integer variable and
let's say user number equals but however
we will get a compiler error here
because read line returns the number in
the string format but here the data type
is integer so string cannot be
implicitly converted to type integer if
you're not sure about what is an
implicit and explicit conversion please
refer to my tutorial on data type
conversions so now we need to convert
the string format into an integer format
okay
and to do that we can use the first
method so int dot parse so what does
this parse method do it takes the string
and converts that to interior since we
are expecting an integer to be entered
by the user
so once we have the user number we can
now compare so if user number is equal
to one then we know that it's one so we
can safely print the message console dot
write line your number is one your
number is one so let's analyze how this
if block works okay so first it comes
here and F statement we'll need to have
a boolean expression okay and this
expression must evaluate to it true or
false if this expression evaluates to
true then this block of code is executed
otherwise it's not okay so if the user
has entered one so let's go ahead and
run this program so it's asking the user
to enter a number so now if I go ahead
and enter one and press Enter look at
this your number is 1 ok because 1 is
equal to 1 this expression has turned to
be true so this line got executed okay
let's more make this program a slightly
bigger one okay so if user number equal
to 2 and if user number equal to 3 so if
user number is 2 we want to say it's 2
on the other hand if it's 3 you want to
say it's 3 all right so now let's go
ahead and run this so please enter a
number now instead of entering 1 2 or 3
I'm going to enter 10 and if I press
Enter look at this decimal but it's not
telling me anything okay
so that's because look at this we end
the time so into user number we have
that value 10 is 10 equal to 1 false so
this is kept
similarly 10 is equal to 2 false this is
kept 10 is equal to 3 Falls this is all
just kept and after that we don't have
anything it just terminus to program so
what I want this program to do is if the
user has not entered any number between
1 2 & 3 he has entered any of the number
apart from these three numbers
I want a message on the screen saying
that your number
is not between 1 2 & 3 so how do we do
that have another if block so if user
number not equal to 1 and user number
not equal to 2 and user number not equal
to 3 so basically what you are
determining here is that if the user
number is not 1 2 & 3 then we want to
print a message saying console.writeline
your number is not between 1 2 & 3 a
number is not between 1 & 3 okay so
what's going to happen if somebody
enters number 5 all these conditions
will become false it comes here okay
ease user number 5 not equal to 1
through 5 not equal to 2 through 5 not
equal to 3 3 so if all of these
conditions see in this F block we have
multiple boolean expressions for this
block of code to be executed all these
conditions must be true even if one of
the conditions is false then this block
of code will not be executed okay
so this is a pretty simple program but
then this program is slightly
inefficient because look at this if you
look at these conditions
all of them are mutually exclusive in a
sense if this number is 1 it cannot be 2
it cannot be three and it cannot be this
okay so in that case instead of using F
if if if you can make use of elsif
because that will make your program much
more in a faster because here even if
the number is one okay if checks this
condition one is equal to one your
number is one it prints that but it
checks this condition again it checks
this condition again and it checks these
conditions again okay now this is extra
processing this isn't required because
the number is one we know that it cannot
be - it cannot be three or any of these
conditions you know it wouldn't satisfy
that so the same program we can actually
make it slightly efficient by using a
variation of if statement so if elsif so
what's going to happen here let's copy
that and finally you can just a else so
what's going to happen now if this
condition is true then it doesn't bother
to do any of this
it will directly come here so it has
saved at some time in terms of
processing so if true executes this if
this is not true only then it will come
here and this checks this and if it is
true then it prints this line and then
skips the rest of the instructions so
the name itself says if do this else if
do this okay and obviously you don't
need to have these conditions because if
it's not one two or three even without
checking the condition you can just
print there is no need of any condition
and else in fact you cannot have that
the compiler will raise that as an error
okay now if you run the program it's
going to work in the same way except
that it's going to be a little more
efficient right now let's say for
example I enter five a number is not
between one and three
obviously five is number not between one
and three okay so that's a simple you
know if statement you can have a simple
if statement you can have if else--if
and an optional else statement as well
and then with the single if statement
you can have multiple conditions as well
separated by ampersands or or singles
let's say for example I ask the user to
enter a number if the number is in our
ten at twenty then I want to say your
number is ten or twenty so how do I do
that if user number is equal to ten or
user number is equal to 20 so this is an
or condition now if if multiple boolean
expressions are separated by R then if
any one of the conditions is true then
this block of code and other statements
that follow the if condition gets
executed so we can say console.writeline
evil number is ten or twenty else you
can do whatever you want
if the number is ten or twenty you know
if any of these conditions are satisfied
in other is you know this piece of code
is executed otherwise this piece of code
is executed okay on the other hand you
can also have single pipe symbol so if
you look at this you know for and you
can either use double ampersand or
single ampersand for or you can use
double pipe symbol or single pipe symbol
so what's the difference between these
two actually if it's double pipe you
know whether if it is double pipe or
single pipe okay would anyone if any one
of the conditions is true then this
piece is code is executed but the
and says if it is double pipe and if
this if the first condition becomes true
it doesn't want to check the second
condition because if one of the
conditions is true that's enough for
this piece of code to be executed but
whereas if it's a single pipe you know
even if this condition is true the
compiler I mean the runtime will go
ahead and check this condition as well
so if it's a single pipe it checks both
the conditions always but if it says if
it's a double pipe then if the first
condition is already true then it
doesn't bother checking the other
condition it checks the second condition
only if the funding first condition is
not true okay so obviously double pipe
will be much faster in some scenarios
where the first condition is true that's
why I always use double pipe and
similarly double ampersand the
difference between the blam sign and
single ampersand if it's double
ampersand you know for the piece of code
for example if I say double ampersand
for this piece of code to be executed
this condition needs to be true and this
condition needs to be true let's say if
this condition is false already there's
no point in checking this condition
because anyway the runtime will skip
executing this because this is already
false so that's what singular I'm in mm
percent does if this condition is false
it doesn't even bother to check this and
goes to the else part whereas if it is
single ampersand even if this condition
is false it will check this condition
and then goes to here and then goes here
so obviously the single ampersand will
check all the conditions whereas you
know the double ampersand will check you
know the next condition only the first
condition is true so that way that's why
this double ampersand and double pipe
symbols are together something called
as short circuit operators because they
don't bother to check all the
expressions in world in a boolean in an
INF or an else block you know all the
time that's why they give us a little
performance benefit so I suggest use in
a double ampersand double pipe very well
you have to use and or or conditions so
so we have to sum up we have seen the if
statement we have seen how if else
statement works we have also seen the
difference between double ampersand and
single ampersand and similarly we have
seen the difference between double pipe
and single pipe that's it for today
thank you for listening have a great day