Perl - Operators


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What is an Operator?

Simple answer can be given using the 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 at all the operators one by one.

Perl Arithmetic Operators

Assume variable $a holds 10 and variable $b holds 20, then following are the Perl arithmatic operators −

Show Example

Sr.No. Operator & Description
1

+ ( Addition )

Adds values on either side of the operator

Example − $a + $b will give 30

2

- (Subtraction)

Subtracts right hand operand from left hand operand

Example −$a - $b will give -10

3

* (Multiplication)

Multiplies values on either side of the operator

Example −$a * $b will give 200

4

/ (Division)

Divides left hand operand by right hand operand

Example −$b / $a will give 2

5

% (Modulus)

Divides left hand operand by right hand operand and returns remainder

Example −$b % $a will give 0

6

** (Exponent)

Performs exponential (power) calculation on operators

Example −$a**$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 the following numeric equality operators −

Show Example

Sr.No. Operator & Description
1

== (equal to)

Checks if the value of two operands are equal or not, if yes then condition becomes true.

Example − ($a == $b) is not true.

2

!= (not equal to)

Checks if the value of two operands are equal or not, if values are not equal then condition becomes true.

Example − ($a != $b) is true.

3

<=>

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.

Example − ($a <=> $b) returns -1.

4

> (greater than)

Checks if the value of left operand is greater than the value of right operand, if yes then condition becomes true.

Example − ($a > $b) is not true.

5

< (less than)

Checks if the value of left operand is less than the value of right operand, if yes then condition becomes true.

Example − ($a < $b) is true.

6

>= (greater than or equal to)

Checks if the value of left operand is greater than or equal to the value of right operand, if yes then condition becomes true.

Example − ($a >= $b) is not true.

7

<= (less than or equal to)

Checks if the value of left operand is less than or equal to the value of right operand, if yes then condition becomes true.

Example − ($a <= $b) is true.

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

Show Example

Sr.No. Operator & Description
1

lt

Returns true if the left argument is stringwise less than the right argument.

Example − ($a lt $b) is true.

2

gt

Returns true if the left argument is stringwise greater than the right argument.

Example − ($a gt $b) is false.

3

le

Returns true if the left argument is stringwise less than or equal to the right argument.

Example − ($a le $b) is true.

4

ge

Returns true if the left argument is stringwise greater than or equal to the right argument.

Example − ($a ge $b) is false.

5

eq

Returns true if the left argument is stringwise equal to the right argument.

Example − ($a eq $b) is false.

6

ne

Returns true if the left argument is stringwise not equal to the right argument.

Example − ($a ne $b) is true.

7

cmp

Returns -1, 0, or 1 depending on whether the left argument is stringwise less than, equal to, or greater than the right argument.

Example − ($a cmp $b) is -1.

Perl Assignment Operators

Assume variable $a holds 10 and variable $b holds 20, then below are the assignment operators available in Perl and their usage −

Show Example

Sr.No. Operator & Description
1

=

Simple assignment operator, Assigns values from right side operands to left side operand

Example − $c = $a + $b will assigned value of $a + $b into $c

2

+=

Add AND assignment operator, It adds right operand to the left operand and assign the result to left operand

Example − $c += $a is equivalent to $c = $c + $a

3

-=

Subtract AND assignment operator, It subtracts right operand from the left operand and assign the result to left operand

Example − $c -= $a is equivalent to $c = $c - $a

4

*=

Multiply AND assignment operator, It multiplies right operand with the left operand and assign the result to left operand

Example − $c *= $a is equivalent to $c = $c * $a

5

/=

Divide AND assignment operator, It divides left operand with the right operand and assign the result to left operand

Example − $c /= $a is equivalent to $c = $c / $a

6

%=

Modulus AND assignment operator, It takes modulus using two operands and assign the result to left operand

Example − $c %= $a is equivalent to $c = $c % a

7

**=

Exponent AND assignment operator, Performs exponential (power) calculation on operators and assign value to the left operand

Example − $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, assume if $a = 60; and $b = 13

Show Example

Sr.No. Operator & Description
1

&

Binary AND Operator copies a bit to the result if it exists in both operands.

Example − ($a & $b) will give 12 which is 0000 1100

2

|

Binary OR Operator copies a bit if it exists in eather operand.

Example − ($a | $b) will give 61 which is 0011 1101

3

^

Binary XOR Operator copies the bit if it is set in one operand but not both.

Example − ($a ^ $b) will give 49 which is 0011 0001

4

~

Binary Ones Complement Operator is unary and has the efect of 'flipping' bits.

Example − (~$a ) will give -61 which is 1100 0011 in 2's complement form due to a signed binary number.

5

<<

Binary Left Shift Operator. The left operands value is moved left by the number of bits specified by the right operand.

Example − $a << 2 will give 240 which is 1111 0000

6

>>

Binary Right Shift Operator. The left operands value is moved right by the number of bits specified by the right operand.

Example − $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

Sr.No. Operator & Description
1

and

Called Logical AND operator. If both the operands are true then then condition becomes true.

Example − ($a and $b) is false.

2

&&

C-style Logical AND operator copies a bit to the result if it exists in both operands.

Example − ($a && $b) is false.

3

or

Called Logical OR Operator. If any of the two operands are non zero then then condition becomes true.

Example − ($a or $b) is true.

4

||

C-style Logical OR operator copies a bit if it exists in eather operand.

Example − ($a || $b) is true.

5

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.

Example − 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

Sr.No. Operator & Description
1

q{ }

Encloses a string with-in single quotes

Example − q{abcd} gives 'abcd'

2

qq{ }

Encloses a string with-in double quotes

Example − qq{abcd} gives "abcd"

3

qx{ }

Encloses a string with-in invert quotes

Example − 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

Sr.No. Operator & Description
1

.

Binary operator dot (.) concatenates two strings.

Example − If $a = "abc", $b = "def" then $a.$b will give "abcdef"

2

x

The repetition operator x returns a string consisting of the left operand repeated the number of times specified by the right operand.

Example − ('-' x 3) will give ---.

3

..

The range operator .. returns a list of values counting (up by ones) from the left value to the right value

Example − (2..5) will give (2, 3, 4, 5)

4

++

Auto Increment operator increases integer value by one

Example − $a++ will give 11

5

--

Auto Decrement operator decreases integer value by one

Example − $a-- will give 9

6

->

The arrow operator is mostly used in dereferencing a method or variable from an object or a class name

Example − $obj->$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


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