# Perl - Operators

## 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 either 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