Perl Operator

Perl operators including numeric operators, string operators, and logical operators.

1. Numeric operators

Perl provides numeric operators to help you operate on numbers including arithmetic, Boolean and bitwise operations. Let’s examine the different kinds of operators in more detail.

Arithmetic operators

Perl arithmetic operators deal with basic math such as adding, subtracting, multiplying, diving, etc. To add (+) or subtract (-) numbers, you would do something as follows:

#!/usr/bin/perl
use warnings;
use strict;

print 10 + 20, "\n"; # 30
print 20 - 10, "\n"; # 10

To multiply or divide numbers, you use divide (/) and multiply (*) operators as follows:

#!/usr/bin/perl
use warnings;
use strict;

print 10 * 20, "\n"; # 200
print 20 / 10, "\n"; # 2

When you combine adding, subtracting, multiplying, and dividing operators together, Perl will perform the calculation in an order, which is known as operator precedence.

The multiply and divide operators have higher precedence than add and subtract operators, therefore, Perl performs multiplying and dividing before adding and subtracting. See the following example:

print 10 + 20/2 - 5 * 2 , "\n"; # 10

Perl performs 20/2 and 5*2 first, therefore you will get 10 + 10 – 10 = 10.

You can use brackets () to force Perl to perform calculations based on the precedence you want as shown in the following example:

print (((10 + 20) / 2 - 5) * 2); # 20;

To raise one number to the power of another number, you use the exponentiation operator.

Exponentiation operators:

#!/usr/bin/perl
use warnings;
use strict;

print 2**3, "\n"; # = 2 * 2 * 2 = 8.
print 3**4, "\n"; # = 3 * 3 * 3 * 3 = 81.

To get the remainder of the division of one number by another, you use the modulo operator (%).

It is handy to use the modulo operator (%) to check if a number is odd or even by dividing it by 2 to get the remainder. If the remainder is zero, the number is even, otherwise, the number is odd. See the following example:

#!/usr/bin/perl
use warnings;
use strict;

print 4 % 2, "\n"; # 0 even
print 5 % 2, "\n"; # 1 odd

Bitwise Operators

Bitwise operators allow you to operate on numbers one bit at a time. Think of a number as a series of bits e.g., 125 can be represented in binary form as 1111101. Perl provides all basic bitwise operators including and (&), or (|), exclusive or (^) , not (~) operators, shift right (>>), and shift left (<<) operators.

The bitwise operators perform from right to left. In other words, bitwise operators perform from the rightmost bit to the leftmost bit.

Bitwise operations

#!/usr/bin/perl
use warnings;
use strict;

my $a = 0b0101; # 5
my $b = 0b0011; # 3

my $c = $a & $b; # 0001 or 1
print $c, "\n";

$c = $a | $b; # 0111 or 7
print $c, "\n";

$c = $a ^ $b; # 0110 or 6
print $c, "\n";

$c = ~$a; # 11111111111111111111111111111010 (64bits computer) or 4294967290
print $c, "\n";

$c = $a >> 1; # 0101 shift right 1 bit, 010 or 2
print $c, "\n";

$c = $a << 1; # 0101 shift left 1 bit, 1010 or 10
print $c, "\n";

Table 1. Comparison operators for numbers
Equality	Operators
Equal	`==`
Not Equal	`!=`
Comparison	`<⇒`
Less than	`<`
Greater than	`>`
Less than or equal	`⇐`
Greater than or equal	`>=`

All the operators in the table above are obvious except the number comparison operator <⇒ which is also known as spaceship operator.

The number comparison operator is often used in sorting numbers. See the code below:

$a <=> $b

1 if $a is greater than $b
0 if $a and $b are equal
-1 if $a is lower than $b

Example

#!/usr/bin/perl
use warnings;
use strict;

my $a = 10;
my $b = 20;

print $a <=> $b, "\n";

$b = 10;
print $a <=> $b, "\n";

$b = 5;
print $a <=> $b, "\n";

2. String operators

Table 2. Comparison operators
Equality	Operators
Equal	`eq`
Not Equal	`ne`
Comparison	`cmp`
Less than	`lt`
Greater than	`gt`
Less than or equal	`le`
Greater than or equal	`ge`

Concatenation operators

Perl provides the concatenation (.) and repetition (x) operators that allow you to manipulate strings

Concatenation operator (.)

print "This is" . " concatenation operator" . "\n";

Repetition operators (x)

print "a message " x 4, "\n";

The chomp() operator

The chomp() operator (or function) removes the last character in a string and returns a number of characters that were removed. The chomp() operator is very useful when dealing with the user’s input because it helps you remove the new line character \n from the string that the user entered.

#!/usr/bin/perl
use warnings;
use strict;

my $s;
chomp($s = <STDIN>);
print $s;

The <STDIN> is used to get input from users.

3. Logical operators

Logical operators are often used in control statements such as if, while, given, etc., to control the flow of the program. The following are logical operators in Perl:

$a && $b performs the logic AND of two variables or expressions. The logical && operator checks if both variables or expressions are true.
$a || $b performs the logic OR of two variables or expressions. The logical || operator checks whether a variable or expression is true.
!$a performs the logic NOT of the variable or expression. The logic ! operator inverts the value of the following variable or expression. In the other words, it converts true to false or false to true.