Question

In Perl:

1. Create a dictionary of at least 5 key/value pairs.
2. Add a new key/value pair to the dictionary.
3. Change one of the values through reassignment.
4. Access at least 3 values using the keys.
5. Access at least 3 keys using the values.
6. Delete an element.
7. Test for key inclusion for 3 elements.
8. Loop through the dictionary, printing out the key and value on the same line separated by a space.

Key1, value1

Key2, value2

…,     …

(Please if you can, provide screenshots)

Thank YOU!

Answer 1

The Perl source code along with the relevant comments is given below.

#!/usr/bin/perl

#create and initialize a dictionary called dict containing five elements
%dict = ('Jean Paul', 55,
         'Lloyd', 32,
         'Khan', 40,
         'Woodie', 26,
         'James', 18);
       
@name = keys %dict;     #name is now an array of all the keys in the dictionary dict
@age = values %dict;    #age is now an array of all the values in the dictionary dict

print "Accessing values using keys:-\n";
#accessing value using keys
print "$name[0]\n";
print "$name[1]\n";
print "$name[2]\n\n";

print "Accessing values using value:-\n";
#accessing value using values
print "$age[0]\n";
print "$age[1]\n";
print "$age[2]\n\n";

print "Adding a new key-value pair:-\n";
#adding a new key value pair to the dictionary dict
$dict{'Albert'} = 65;

print "\$dict{'Albert'} = $dict{'Albert'}\n\n";

print "Update an existing key-value pair:-\n";
#updating an existing pair using assignment
$dict{'James'} = 30;
print "\$dict{'James'} = $dict{'James'}\n\n";

print "Delete a key-value pair:-\n\n";
#delete a key value pair
delete $dict{'Lloyd'};

print "Checking for key existence:-\n";
#check if a key exists in the dictionary
if(exists($dict{'Lloyd'}))
{   print "\$dict{'Lloyd'} value found\n";}
else
{   print "\$dict{'Lloyd'} - no records found\n";}

if(exists($dict{'Khan'}))
{   print "\$dict{'Khan'} value found\n";}
else
{   print "No records found\n";}

if(exists($dict{'Albert'}))
{   print "\$dict{'Albert'} value found\n\n";}
else
{   print "No records found\n\n";}

print "Iterating the dictionary using while loop:-\n";
#iterating dictionary using while loop
while(my($k, $v) = each %dict)
{   print "$k, $v\n"
}

If the indendation are not clear, please refer the screenshot of the code given below.

The screenshot of the output is also given below.

Explanation

• Dictionary or a hash is a data structure which holds data in the form of a key value pair structure. The key and value can be initialized to a hash by either using , or => symbols.
• A dictionary dict is initialized with five elements.
• Using the keywords keys and values, the key and value of the dictionary will be stored into respective arrays.
• Deletiion of an element can be done using the keyword delete. Eg: delete $dict{'Lloyd'};
• To check whether a key value pair exist in a dictionary, the command exists can be used. Eg: exists($dict{'Albert'})
• Iterating a dictionary can be done using a while loop. The each keyword is used to update the state of the hash after each iteration.

Hope this helps. Doubts, if any, can be asked in the comment section.