Back-End Programming Exam > Back-End Programming Videos > Perl Building Blocks: An Introduction to Perl > Perl Tutorial - 15: Obtaining Keys & Values from Hashes
Perl Tutorial - 15: Obtaining Keys & Values from Hashes Video Lecture | Perl Building Blocks: An Introduction to Perl - Back-End Programming
FAQs on Perl Tutorial - 15: Obtaining Keys & Values from Hashes Video Lecture - Perl Building Blocks: An Introduction to Perl - Back-End Programming
| 1. How can I obtain all the keys from a hash in Perl? |  |
Ans. To obtain all the keys from a hash in Perl, you can use the `keys` function. It returns a list of all the keys of the hash. Here's an example:
```
my %hash = (name => "John", age => 25, city => "New York");
my @keys = keys %hash;
print @keys; # Output: nameagecity
```
| 2. How can I obtain all the values from a hash in Perl? | |
Ans. To obtain all the values from a hash in Perl, you can use the `values` function. It returns a list of all the values of the hash. Here's an example:
```
my %hash = (name => "John", age => 25, city => "New York");
my @values = values %hash;
print @values; # Output: John25New York
```
| 3. Can I obtain both the keys and values from a hash in Perl? | |
Ans. Yes, you can obtain both the keys and values from a hash in Perl using the `each` function. It returns a list containing two elements: the key and the corresponding value. Here's an example:
```
my %hash = (name => "John", age => 25, city => "New York");
while (my ($key, $value) = each %hash) {
print "$key: $value\n";
}
```
Output:
```
name: John
age: 25
city: New York
```
| 4. How can I check if a specific key exists in a hash in Perl? | |
Ans. To check if a specific key exists in a hash in Perl, you can use the `exists` function. It returns true if the key exists in the hash, and false otherwise. Here's an example:
```
my %hash = (name => "John", age => 25, city => "New York");
if (exists $hash{name}) {
print "Key 'name' exists in the hash.\n";
} else {
print "Key 'name' does not exist in the hash.\n";
}
```
Output:
```
Key 'name' exists in the hash.
```
| 5. How can I obtain the number of key-value pairs in a hash in Perl? | |
Ans. To obtain the number of key-value pairs in a hash in Perl, you can use the `scalar` function in combination with the `keys` function. The `keys` function returns a list of all the keys, and the `scalar` function returns the size of the list. Here's an example:
```
my %hash = (name => "John", age => 25, city => "New York");
my $count = scalar keys %hash;
print "Number of key-value pairs: $count\n";
```
Output:
```
Number of key-value pairs: 3
```
Text Transcript from Video
hello guys welcome to my channel this is
the 15th tutorial in this course and in
this role we're gonna see how we can
obtain just the keys and just the values
from a hash in Perl so we're going to
work with the script called hashes
underscore keys underscore values and in
this script as you can see on line
number three I have created a hash
called 10s and it's structure is similar
to the player's hash that we've been
working with in the last tutorial so you
know I've got the ranks as the keys and
the player names as the values it's just
that in this tutorial we've already yet
another key value pair to this hash so
we have Berdych at number five so K is
at number four and these are number
three Rogers at number two and Novak is
at number one and then let's say you
just want the keys from this hash so you
know the keys are one two three four and
five so to obtain the keys you would use
the keys subroutine and this is actually
more for command than a subroutine so
you know just as print you don't have to
put anything within parentheses you
don't have to pass something as an
argument it's just that you type in the
keyword keys give a space and then type
the name of your hash along with the
percent symbol you know this time you
have to use the percent symbol and not
the add the rate symbol and that's even
though you are fetching list values but
since this is not exactly you know like
the subroutines that we checked out in
the last tutorial you have to use the
percent symbol here so to store the keys
I have created an array variable called
ranks and similarly to store the values
you use the values keyword so I have
stored the values in an array variable
called players so at players equals
values % tennis and that that should do
the job and then on line number 8 I have
a print statement that's going to
display all the keys and on line number
nine I have a print statement that's
going to display all the values so for
keys we print at ranks and for values we
and at players so let me show you the
output of the script there we go we see
that the keys are 4 1 3 2 and 5 and as
you can see they're not sorted and the
values are K Novak and E Roger and
Berdych so that's it for this tutorial I
hope you guys had fun watching this and
you may subscribe to my channel if you
haven't already I'm going to see you in
the next video in which we are going to
continue our discussion on Perl and
that's it for the time being I'll see
you soon till then take care
the 15th tutorial in this course and in
this role we're gonna see how we can
obtain just the keys and just the values
from a hash in Perl so we're going to
work with the script called hashes
underscore keys underscore values and in
this script as you can see on line
number three I have created a hash
called 10s and it's structure is similar
to the player's hash that we've been
working with in the last tutorial so you
know I've got the ranks as the keys and
the player names as the values it's just
that in this tutorial we've already yet
another key value pair to this hash so
we have Berdych at number five so K is
at number four and these are number
three Rogers at number two and Novak is
at number one and then let's say you
just want the keys from this hash so you
know the keys are one two three four and
five so to obtain the keys you would use
the keys subroutine and this is actually
more for command than a subroutine so
you know just as print you don't have to
put anything within parentheses you
don't have to pass something as an
argument it's just that you type in the
keyword keys give a space and then type
the name of your hash along with the
percent symbol you know this time you
have to use the percent symbol and not
the add the rate symbol and that's even
though you are fetching list values but
since this is not exactly you know like
the subroutines that we checked out in
the last tutorial you have to use the
percent symbol here so to store the keys
I have created an array variable called
ranks and similarly to store the values
you use the values keyword so I have
stored the values in an array variable
called players so at players equals
values % tennis and that that should do
the job and then on line number 8 I have
a print statement that's going to
display all the keys and on line number
nine I have a print statement that's
going to display all the values so for
keys we print at ranks and for values we
and at players so let me show you the
output of the script there we go we see
that the keys are 4 1 3 2 and 5 and as
you can see they're not sorted and the
values are K Novak and E Roger and
Berdych so that's it for this tutorial I
hope you guys had fun watching this and
you may subscribe to my channel if you
haven't already I'm going to see you in
the next video in which we are going to
continue our discussion on Perl and
that's it for the time being I'll see
you soon till then take care
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Nov 22, 2024 Last updated |
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