Perl - Operators

Perl - Operators

What is an operator?

Simple answer can be given using expression 4 + 5 is equal to 9. Here 4 and 5 are called operands and + is called operator. Perl language supports many operator types but following is a list of important and most frequently used operators:

·        Arithmetic Operators

·        Equality Operators

·        Logical Operators

·        Assignment Operators

·        Bitwise Operators

·        Logical Operators

·        Quote-like Operators

·        Miscellaneous Operators

Lets have a look on all operators one by one.

Perl Arithmetic Operators:

Assume variable $a holds 10 and variable $b holds 20 then:

[ Show Example ]

Operator	Description	Example
+	Addition - Adds values on either side of the operator	$a + $b will give 30
-	Subtraction - Subtracts right hand operand from left hand operand	$a - $b will give -10
*	Multiplication - Multiplies values on either side of the operator	$a * $b will give 200
/	Division - Divides left hand operand by right hand operand	$b / $a will give 2
%	Modulus - Divides left hand operand by right hand operand and returns remainder	$b % $a will give 0
**	Exponent - Performs exponential (power) calculation on operators	$a**$b will give 10 to the power 20

Perl Equality Operators:

These are also called relational operators. Assume variable $a holds 10 and variable $b holds 20 then, lets check following numeric equality operators:

[ Show Example ]

Operator	Description	Example
==	Checks if the value of two operands are equal or not, if yes then condition becomes true.	($a == $b) is not true.
!=	Checks if the value of two operands are equal or not, if values are not equal then condition becomes true.	($a != $b) is true.
<=>	Checks if the value of two operands are equal or not, and returns -1, 0, or 1 depending on whether the left argument is numerically less than, equal to, or greater than the right argument.	($a <=> $b) returns -1.
>	Checks if the value of left operand is greater than the value of right operand, if yes then condition becomes true.	($a > $b) is not true.
<	Checks if the value of left operand is less than the value of right operand, if yes then condition becomes true.	($a < $b) is true.
>=	Checks if the value of left operand is greater than or equal to the value of right operand, if yes then condition becomes true.	($a >= $b) is not true.
<=	Checks if the value of left operand is less than or equal to the value of right operand, if yes then condition becomes true.	($a <= $b) is true.

Below is a list of equity operators. Assume variable $a holds "abc" and variable $b holds "xyz" then, lets check following string equality operators:

[ Show Example ]

Operator	Description	Example
lt	Returns true if the left argument is stringwise less than the right argument.	($a lt $b) is true.
gt	Returns true if the left argument is stringwise greater than the right argument.	($a gt $b) is false.
le	Returns true if the left argument is stringwise less than or equal to the right argument.	($a le $b) is true.
ge	Returns true if the left argument is stringwise greater than or equal to the right argument.	($a ge $b) is false.
eq	Returns true if the left argument is stringwise equal to the right argument.	($a eq $b) is false.
ne	Returns true if the left argument is stringwise not equal to the right argument.	($a ne $b) is true.
cmp	Returns -1, 0, or 1 depending on whether the left argument is stringwise less than, equal to, or greater than the right argument.	($a cmp $b) is -1.

Perl Assignment Operators:

Assume variable $a holds 10 and variable $b holds 20 then:

[ Show Example ]

Operator	Description	Example
=	Simple assignment operator, Assigns values from right side operands to left side operand	$c = $a + $b will assigne value of $a + $b into $c
+=	Add AND assignment operator, It adds right operand to the left operand and assign the result to left operand	$c += $a is equivalent to $c = $c + $a
-=	Subtract AND assignment operator, It subtracts right operand from the left operand and assign the result to left operand	$c -= $a is equivalent to $c = $c - $a
*=	Multiply AND assignment operator, It multiplies right operand with the left operand and assign the result to left operand	$c *= $a is equivalent to $c = $c * $a
/=	Divide AND assignment operator, It divides left operand with the right operand and assign the result to left operand	$c /= $a is equivalent to $c = $c / $a
%=	Modulus AND assignment operator, It takes modulus using two operands and assign the result to left operand	$c %= $a is equivalent to $c = $c % a
**=	Exponent AND assignment operator, Performs exponential (power) calculation on operators and assign value to the left operand	$c **= $a is equivalent to $c = $c ** $a

Perl Bitwise Operators:

Bitwise operator works on bits and perform bit by bit operation. Assume if $a = 60; and $b = 13; Now in binary format they will be as follows:

$a = 0011 1100

$b = 0000 1101

-----------------

$a&$b = 0000 1100

$a|$b = 0011 1101

$a^$b = 0011 0001

~$a  = 1100 0011

There are following Bitwise operators supported by Perl language

[ Show Example ]

Operator	Description	Example
&	Binary AND Operator copies a bit to the result if it exists in both operands.	($a & $b) will give 12 which is 0000 1100
|	Binary OR Operator copies a bit if it exists in eather operand.	($a | $b) will give 61 which is 0011 1101
^	Binary XOR Operator copies the bit if it is set in one operand but not both.	($a ^ $b) will give 49 which is 0011 0001
~	Binary Ones Complement Operator is unary and has the efect of 'flipping' bits.	(~$a ) will give -61 which is 1100 0011 in 2's complement form due to a signed binary number.
<<	Binary Left Shift Operator. The left operands value is moved left by the number of bits specified by the right operand.	$a << 2 will give 240 which is 1111 0000
>>	Binary Right Shift Operator. The left operands value is moved right by the number of bits specified by the right operand.	$a >> 2 will give 15 which is 0000 1111

Perl Logical Operators:

There are following logical operators supported by Perl language. Assume variable $a holds true and variable $b holds false then:

[ Show Example ]

Operator	Description	Example
and	Called Logical AND operator. If both the operands are true then then condition becomes true.	($a and $b) is false.
&&	C-style Logical AND operator copies a bit to the result if it exists in both operands.	($a && $b) is false.
or	Called Logical OR Operator. If any of the two operands are non zero then then condition becomes true.	($a or $b) is true.
||	C-style Logical OR operator copies a bit if it exists in eather operand.	($a || $b) is true.
not	Called Logical NOT Operator. Use to reverses the logical state of its operand. If a condition is true then Logical NOT operator will make false.	not($a and $b) is true.

Quote-like Operators:

There are following Quote-like operators supported by Perl language. In the following table, a {} represents any pair of delimiters you choose.

[ Show Example ]

Operator	Description	Example
q{ }	Encloses a string with-in single quotes	q{abcd} gives 'abcd'
qq{ }	Encloses a string with-in double quotes	qq{abcd} gives "abcd"
qx{ }	Encloses a string with-in invert quotes	qx{abcd} gives `abcd`

Miscellaneous Operators:

There are following miscellaneous operators supported by Perl language. Assume variable a holds 10 and variable b holds 20 then:

[ Show Example ]

Operator	Description	Example
.	Binary operator dot (.) concatenates two strings.	If $a="abc", $b="def" then $a.$b will give "abcdef"
x	The repetition operator x returns a string consisting of the left operand repeated the number of times specified by the right operand.	('-' x 3) will give ---.
..	The range operator .. returns a list of values counting (up by ones) from the left value to the right value	(2..5) will give (2, 3, 4, 5)
++	Auto Increment operator increases integer value by one	$a++ will give 11
--	Auto Decrement operator decreases integer value by one	$a-- will give 9
->	The arrow operator is mostly used in dereferencing a method or variable from an object or a class name	$obj->$a is an example to access variable $a from object $obj.

Perl Operators Precedence

The following table lists all operators from highest precedence to lowest.

[ Show Example ]

left     terms and list operators (leftward)

left     ->

nonassoc ++ --

right    **

right    ! ~ \ and unary + and -

left     =~ !~

left     * / % x

left     + - .

left     << >>

nonassoc named unary operators

nonassoc < > <= >= lt gt le ge

nonassoc == != <=> eq ne cmp ~~

left     &

left     | ^

left     &&

left     || //

nonassoc ..  ...

right    ?:

right    = += -= *= etc.

left     , =>

nonassoc list operators (rightward)

right    not

left     and

left     or xor