Perl Tutorial - 13: Hashes Video Lecture | Perl Building Blocks: An Introduction to Perl - Back-End Programming

hello guys welcome to my channel this is
the 13th tutorial in this course and in
this tutorial we are going to talk about
hashes in Perl so a hash is a set of key
value pairs and let's say you were
building a phone book so the kind of
information that you would want to put
in your phone book you would want to
store names you would want to store
email addresses and you would definitely
want to store contact numbers so each of
these items or entries in the phone book
would be a key value pair so you would
have name as a key and you would have a
corresponding value and then you would
have email address as a key and a value
for email address and you would have
phone number as a key and you would have
a value for phone number so a hash in
Perl provides you a structure in which
you can organize information in such a
way so to demonstrate hashes I've got a
script here which is called hashes dot
PL and in this script on line number 3 I
have created a hash called players and
just as you use a dollar symbol to
create scalar variables and the ad rate
symbol to create array variables you use
the percent symbol to create a hash so
you put the percent symbol and a name
for your hash the equal to symbol and
then within parenthesis you have to type
in your key value pairs
so in this hash I am going to store
ranks as keys and the names of tennis
players that are holding the you know
those positions so the number one tennis
player in the world is Novak Djokovic so
Novak is going to be the value and one
is going to be the key so one is the
rank here and Novak is the name of the
player and actually at the time of this
recording Andy Murray is the number two
player in the world and Roger Federer is
round three but the time when I wrote
this script Federer was actually rank
two so that's how I have it so two is
the rank for Federer and Roger is the
value so you put the key first and then
you put in equal to sign and then you
put the greater than symbol that's how
you define a key value relationship
within a
in pole and similarly I have an entry
for Andy Murray here and next I have a
hash called capitals which has names of
countries as the keys and you know the
corresponding capitals is the value so
over here in the players hash
I have numeric keys that's why I do I
haven't enclosed the keys within the
courts whereas in the Capitals
hash I have texts keys so that's why I
have put India and the US within
double-quotes and then the corresponding
capitals of course have to be put within
double-quotes New Delhi and Washington
DC right so this one has three key value
pairs while this one has only two key
value pairs the next thing that we have
to learn is to fetch values from a hash
so on line number six I have a print
statement that is going to first display
the text best player and then we are
supposed to display in no action him
here because he holds the number one
position so to do that you have to put
the dollar symbol because you're
displaying a scalar value so you put the
dollar symbol and then the name of your
hash which is players and then within
curly braces you are supposed to put the
key for which you want the value to be
pulled out so you know Novak's key is
one so that's why we put one here within
curly braces and on line number seven
I've got another print statement which
is going to display India's capital so
dollar Capitals capitals is the name of
this hash and then within curly braces
again and quotes I type in India which
is the name of the key and we should see
New Delhi there so I'll make sure the
script is saved and I'll press f5 to run
it so there we go we see that the best
player is Novak and India's capital is
New Delhi so that's it for this tutorial
I'm going to see you in the next video I
hope you guys had fun watching this one
and you may subscribe to my channel I'll
see you soon take care