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 −

[ 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 the 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 assigned 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


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