Perl Tutorial - 40: Logical Operators Video Lecture | Perl Building Blocks: An Introduction to Perl - Back-End Programming

hello guys welcome to my channel this is
the fortieth video in this playlist and
in this tutorial we'll be talking about
logical operators in Perl so I've got a
script here that's called logical
underscore operators and in the script
on line number three I have created a
variable X and I've given it a value
minus 16 now let's say you want to test
if X is positive and even so you know
you would do that using two conditions
obviously first of all you would have to
check if the value in X is greater than
zero we are doing that through this
condition here and then you would also
have to check whether the remainder when
you divide X or the value in X by 2 is
equal to 0 or not and you would do that
using this condition here but for X to
be positive as well as even both these
conditions have to be simultaneously
true it cannot be that you know only one
condition is true because if X is
greater than 0 but this value is to
false and it would mean that X is
positive but it is odd it's not even and
if this would be true and this won't be
true then you could say that X is even
but it's negative it's not positive
right so for both conditions to be true
you have to put a logical and operator
between the two conditions to ensure
that they simultaneously turn out to be
true only if that happens only then we
would get inside this if block which
starts at line number 6 and ends at line
number 8 and we would execute the print
statement that we have on line number 7
which is going to display the message
value in X is positive and even now if
you would want to see where the value in
X is positive or even then it won't
matter you know X could either be
positive or it could be even one of the
two conditions could be true and that's
why you would put or instead of and so
this is the logical or operator you just
have to type the word or between the two
conditions and if either of the two
conditions would be true we would get
inside the if block and execute the
prints
on line number 11 which would display
the text value in X is either positive
or negative and then finally on line
number 13 I have an if statement that
uses the not logical operator and you
know let's take a look at the test
condition here it's X is greater than 0
so if not wasn't present we would have
executed the code in this if block if X
would have been positive but since we
have not here the truth value of this
evaluation would be reversed and you
know we would actually execute the code
inside the if block if X would be less
than or equal to 0 you know that is if X
would be negative and that's why online
was 15 I have a print statement that
would display the message value when X
is negative so and make sure this file
is saved and I'll press f5 to run the
script and with the current value minus
16 we see minus 16 is either positive or
even it is even it's not positive course
and then we also see minus 16 is
negative and if I would change this to
just 16 take out the minus sign then we
see 16 is positive and even and 16 is
either positive or even of course and
let me change this to an odd number let
me change this to 17 and we would see 17
is either positive or even its positive
it's not even so that's how the logical
operators in Perl work 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
tutorial till then take care