Part 13 - C# Tutorial - while loop in c# Video Lecture - C sharp Enhance

hello welcome to presume technologies I
am venket this is part 13 loops in
c-sharp
in this session we'll talk about while
loop in c-sharp there are four different
types of loops while you do a loop for
loop for each loop in a later session
we'll talk about the other loops in this
session we will talk about while loop so
let's you get an example now I want you
to write a c-sharp program using while
loop which will ask the user to enter
his target number let's say for example
if the user enters can then you program
should print even numbers under the ten
just like this okay so let's write our
program let's copy that so we want to
ask the user to enter his target number
so consumed or treadline so prompt the
user to enter his target and then once
the user enters his target we need to
read that from the console so console
dot readline so we read the number
that's entered by the user and we need a
variable to store that so let's create a
new variable use a target equals that
but console door try to read line reads
the number has a string format from the
console so we need to convert that into
integer and to do that we can use the
parse method so in dot parse so now we
have the user's target now we need to
start printing even numbers from zero
until the target so we need a variable
in order to start at zero let's create
an integer variable called start and
initialize that to zero now while
start is less than or equal to use a
target what we need to do we need to
print start and then we need to
increment start by 2 so what's happening
here so this is the beginning of the
while loop ok while and then we have a
boolean expression here while start
start at the moment is 0 well start is
less than or equal to use the target if
the user has entered 10 zero is less
than or equal to 10 so this boolean
expression will be evaluated to true and
the control gets into the block here it
prints out the start start at the moment
is 0 so it prints on 0 and then it
increments the value of start by 2 and
then comes to check the expression once
again it's 2 less than or equal to 10
that's true prince2
increments in 2 pi to start becomes 4 so
this process is repeated until this
expression is evaluated to false so
let's imagine what's going to happen
when the value of start is 10 when is
them less than or equal to 10 that's
true comes here prints 10 increment the
start variable by another 2 so start
becomes 12 is 12 less than or equal to
10 that condition is false so it skips
this block comes here and terminates the
program so let's see this program in
action when I press control f5 to run
this program
please enter you target let's say 10 0 2
4 6 8 10 press any key to continue the
program terminates now let's say what's
going to happen if I forget to have this
condition there if you don't have that
line there the start will always be 0
and if the user has entered 10
zero will always be less than or equal
to 10 and this condition will never
become true because of verge the control
will never come out of this while loop
so we will create a never-ending loop
let me quickly run this program but
before I run that let me open the task
manager so I can I can show you the
processor ok the processor usage
currently is that you know 70% ok let's
go ahead and run this program please
enter your target okay now let's say I
enter my target as 10
look at this it's printing 0 0 0 0 and
look at the processing usage it's just
going up and up now that's basically
because our program has got into a
never-ending loop this program is never
going to end because start will always
be 0 and 0 will always be less than or
equal to 10 and this condition will
always be true so it continues to print
that never ending Lee ok so now the
moment I close this program the
processor usage will fall down
automatically so remember that's very
important to update the variable that
participates in the boolean expression
so that it becomes it makes the
condition falls at some point time and
the loop will ultimately end otherwise
we risk creating never-ending loops and
if you look at the output that I wanted
I want the output to be present in the
same line but if you look at our program
it prints even number on every even
number on a new line for example I say
10 let's run this once again represent
control f5 way into 10 it prints each
even number on a new line I want all the
you numbers on the same line and do that
we can say consult or try but we'll have
a small problem here which will
then look at this all even numbers of
are concatenated together I want a space
between each even number in that case
just up in this space here now if I go
ahead and run this and there your target
so each even number has a space between
them alright so we have seen how to use
a while loop and print even numbers in
our next session we'll actually talk
about do-while loop okay let's review
while loop while loop as we know it
checks the condition fast and if that
condition is true statements within the
loop are executed this process continues
as long has the boolean condition
evaluates to true the moment it becomes
false I know it escapes the blocks and
go to the next statement after the while
loop and very important keep in mind to
update the variable that participates in
the condition so that the loop can end
at some point so in the next session
we'll talk about do-while loop and then
we'll find out the differences between
while and do-while loop that's it for
today thank you for listening
have a great day