Perl Tutorial - 25: While Loop Video Lecture | Perl Building Blocks: An Introduction to Perl - Back-End Programming

hello guys welcome to my channel this is
the 25th tutorial in this course and in
this tutorial we'll be talking about the
while loop in Perl so a loop in
programming allows you to execute a
bunch of statements a bunch of times
right and if you have some piece of code
that you might want to execute multiple
times and you have to use loops and you
know among the options that are
available to us in the family of loops
the while loop is my personal favorite
and that's why I decided to start the
discussion on loops with the while loop
and also in terms of syntax it's it's
very simple so you could decide the
number of times you want to execute you
know certain piece of code on the basis
of some condition or you could decide
that number in advance like you know in
in in this case what I'm trying to do by
the way the script that I'm using in
this tutorial is called while and this
script on line number 3 I have created a
scalar variable X which has a value 10
so what I'm trying to do is you know
display values of x from 10 till 20 and
there are two things that I have to do
first of all I have to display the value
of x and you know from 10 to 20 I'll
have to display 10 values and then I
also have to update the value of x so
that we see a different value each time
we don't want to see ten ten times you
want to see 10 11 12 13 so on and so
forth and also we need to check when X
reaches 20 because if it reaches 20 then
we have to stop printing you know if I
put two million here then maybe the
script would just keep on executing and
you know it would run into some kind of
an endless loop and we don't want that
so this number has to be well within
reach of you know feasible range
basically so the syntax of while loop is
very simple on line number five I have
written the keyword while and then
within parenthesis you just have to put
your condition so in our case
dition is that X has to be less than or
equal to 20 let me you know in fact just
make it less than 20 so that we don't
even see 20 and then within the body of
vile you start the body of while with an
opening curly brace and you end it with
the closing curly brace similar to if or
else and then on line number seven I
have a print statement that is just
going to display the value of x the
current value of x and then since I
don't want this loop to run forever and
have to update the value of X so that
this value gets nearer and nearer to
this value right so the step by which I
update the value of X determines the
number of times this loop is going to
run so if suppose I type in here door x
is equal to door x plus hundred then the
loop is only going to have one eye
tration because it's gonna check whether
10 is less than 20 of course it is so
it's gonna print the value of X then
it's going to update X it's going to
make it 110 and then 110 is not going to
be less than 20 so it's not going to
execute whatever is there inside the
body of while right so let me execute
the script and we see numbers from 10 to
19 10 11 12 13 14 and if I change the
step size to 5 instead of 1 you know
you're only gonna have two variations 10
and 15 because the third time X becomes
20 and it is no longer less than 20 if I
would put equal to here then you know
the loop would have three iterations so
that is while loop for you I hope you
guys had fun watching this video you may
subscribe to my channel if you haven't
already I'm going to see you in the next
video till then take care