Variables are the reserved memory locations to store values. This means that when you create a variable you reserve some space in memory.

Based on the data type of a variable, the interpreter allocates memory and decides what can be stored in the reserved memory. Therefore, by assigning different data types to variables, you can store integers, decimals, or strings in these variables.

We have learnt that Perl has the following three basic data types −

• Scalars
• Arrays
• Hashes

Accordingly, we are going to use three types of variables in Perl. A scalar variable will precede by a dollar sign ($) and it can store either a number, a string, or a reference. An array variable will precede by sign @ and it will store ordered lists of scalars. Finaly, the Hash variable will precede by sign % and will be used to store sets of key/value pairs.

Perl maintains every variable type in a separate namespace. So you can, without fear of conflict, use the same name for a scalar variable, an array, or a hash. This means that $foo and @foo are two different variables.

Creating Variables

Perl variables do not have to be explicitly declared to reserve memory space. The declaration happens automatically when you assign a value to a variable. The equal sign (=) is used to assign values to variables.

Keep a note that this is mandatory to declare a variable before we use it if we use use strict statement in our program.

The operand to the left of the = operator is the name of the variable, and the operand to the right of the = operator is the value stored in the variable. For example −

$age = 25;             # An integer assignment
$name = "John Paul";   # A string 
$salary = 1445.50;     # A floating point

Here 25, “John Paul” and 1445.50 are the values assigned to $age, $name and $salary variables, respectively. Shortly we will see how we can assign values to arrays and hashes.

Scalar Variables

A scalar is a single unit of data. That data might be an integer number, floating point, a character, a string, a paragraph, or an entire web page. Simply saying it could be anything, but only a single thing.

Here is a simple example of using scalar variables −

#!/usr/bin/perl

$age = 25;             # An integer assignment
$name = "John Paul";   # A string 
$salary = 1445.50;     # A floating point

print "Age = $agen";
print "Name = $namen";
print "Salary = $salaryn";

Age = 25
Name = John Paul
Salary = 1445.5

#!/usr/bin/perl

@ages = (25, 30, 40);             
@names = ("John Paul", "Lisa", "Kumar");

print "$ages[0] = $ages[0]n";
print "$ages[1] = $ages[1]n";
print "$ages[2] = $ages[2]n";
print "$names[0] = $names[0]n";
print "$names[1] = $names[1]n";
print "$names[2] = $names[2]n";

$ages[0] = 25
$ages[1] = 30
$ages[2] = 40
$names[0] = John Paul
$names[1] = Lisa
$names[2] = Kumar

#!/usr/bin/perl

%data = (''John Paul'', 45, ''Lisa'', 30, ''Kumar'', 40);

print "$data{''John Paul''} = $data{''John Paul''}n";
print "$data{''Lisa''} = $data{''Lisa''}n";
print "$data{''Kumar''} = $data{''Kumar''}n";

$data{''John Paul''} = 45
$data{''Lisa''} = 30
$data{''Kumar''} = 40

#!/usr/bin/perl

@names = (''John Paul'', ''Lisa'', ''Kumar'');

@copy = @names;
$size = @names;

print "Given names are : @copyn";
print "Number of names are : $sizen";

Given names are : John Paul Lisa Kumar
Number of names are : 3