Perl Scalars

A scalar is a simple unit of data.

A scalar can be an integer, a floating-point number, a character, a string, a paragraph, or an entire web page.

The following example demonstrates the simple application of scalars:

Example

#!/usr/bin/perl

$age = 20;             # Integer assignment
$name = "tutorialpro"; # String
$salary = 130.50;      # Floating-point number

print "Age = $age\n";
print "Name = $name\n";
print "Salary = $salary\n";

Executing the above program, the output is:

Age = 20
Name = tutorialpro
Salary = 130.5

Numeric Scalars

Scalars are typically numbers or strings. The following example demonstrates the use of different types of numeric scalars:

Example

#!/usr/bin/perl

$integer = 200;
$negative = -300;
$floating = 200.340;
$bigfloat = -1.2E-23;

# Octal 377, decimal 255
$octal = 0377;

# Hexadecimal FF, decimal 255
$hexa = 0xff;

print "integer = $integer\n";
print "negative = $negative\n";
print "floating = $floating\n";
print "bigfloat = $bigfloat\n";
print "octal = $octal\n";
print "hexa = $hexa\n";

Executing the above program, the output is:

integer = 200
negative = -300
floating = 200.34
bigfloat = -1.2e-23
octal = 255
hexa = 255

String Scalars

The following example demonstrates the use of different types of string scalars, noting the difference between single and double quotes:

Example

#!/usr/bin/perl

$var = "String Scalar - tutorialpro.org!";
$quote = 'I am inside single quotes - $var';
$double = "I am inside double quotes - $var";

$escape = "Escape character usage -\tHello, World!";

print "var = $var\n";
print "quote = $quote\n";
print "double = $double\n";
print "escape = $escape\n";

Executing the above program, the output is:

var = String Scalar - tutorialpro.org!
quote = I am inside single quotes - $var
double = I am inside double quotes - String Scalar - tutorialpro.org!
escape = Escape character usage -    Hello, World!

Scalar Operations

The following example demonstrates simple operations with scalars:

Example

#!/usr/bin/perl

$str = "hello" . "world";       # String concatenation
$num = 5 + 10;                  # Addition of two numbers
$mul = 4 * 5;                   # Multiplication of two numbers
$mix = $str . $num;             # Concatenation of string and number

print "str = $str\n";
print "num = $num\n";
print "mix = $mix\n";

Executing the above program, the output is:

str = helloworld
num = 15
mix = helloworld15

Multiline Strings

We can use single quotes to output multiline strings, as shown below:

Example

#!/usr/bin/perl

$string = '
tutorialpro.org
    —— Learning is not only about technology, but also about dreams!
';

print "$string\n";

Executing the above program, the output is:

tutorialpro.org
    —— Learning is not only about technology, but also about dreams!

You can also use the "here" document syntax to output multiline strings:

Example

#!/usr/bin/perl

print <&lt;EOF;
tutorialpro.org
    —— Learning is not only about technology, but also about dreams!
EOF

Executing the above program, the output is:

tutorialpro.org
    —— Learning is not only about technology, but also about dreams!

Special Characters

The following demonstrates the application of special characters in Perl, such as __FILE__, __LINE__, and __PACKAGE__, which represent the current script's filename, line number, and package name, respectively.

Note: __ is two underscores, __FILE__ has two underscores before and after.

These special characters are standalone tokens and cannot be written inside strings, for example:

Example

#!/usr/bin/perl

print "Filename " . __FILE__ . "\n";
print "Line Number " . __LINE__ . "\n";
print "Package Name " . __PACKAGE__ . "\n";

# Cannot be parsed
print "__FILE__ __LINE__ __PACKAGE__\n";

Executing the above program, the output is:

Filename test.pl
Line Number 4
Package Name main
__FILE__ __LINE__ __PACKAGE__

v-Strings

A string starting with 'v' followed by one or more integers separated by dots is treated as a string literal.

When you want to declare the numeric value of each character directly, v-strings provide a clearer way to construct such strings compared to something like "\x{1}\x{14}\x{12c}\x{fa0}", which is less understandable. We can see the following example:

Example

#!/usr/bin/perl

$smile = v9786;
$foo = v102.111.111;
$martin = v77.97.114.116.105.110;

print "smile = $smile\n";
print "foo = $foo\n";
print "martin = $martin\n";

Executing the above program, the output is:

Wide character in print at test.pl line 7.
smile = ☺
foo = foo
martin = Martin