Python Operators

Python Operators in general are used to perform operations on values and variables. These are standard symbols used for the purpose of logical and arithmetic operations. In this article, we will look into different types of Python operators. 

• OPERATORS: Are the special symbols. Eg- + , * , /, etc.
• OPERAND: It is the value on which the operator is applied.

Arithmetic Operators

Arithmetic operators are used to performing mathematical operations like addition, subtraction, multiplication, and division.

• In Python 3.x the result of division is a floating-point while in Python 2.x division of 2 integer was an integer and to obtain an integer result in Python 3.x floored (// integer) is used.

Operator	Description	Syntax
+	Addition: adds two operands	x + y
–	Subtraction: subtracts two operands	x – y
*	Multiplication: multiplies two operands	x * y
/	Division (float): divides the first operand by the second	x / y
//	Division (floor): divides the first operand by the second	x // y
%	Modulus: returns the remainder when the first operand is divided by the second	x % y
**	Power: Returns first raised to power second	x ** y

PRECEDENCE:

• P – Parentheses
• E – Exponentiation
• M – Multiplication     (Multiplication and division have the same precedence)
• D – Division
• A – Addition     (Addition and subtraction have the same precedence)
• S – Subtraction

The modulus operator helps us extract the last digit/s of a number. For example:

• x % 10 -> yields the last digit
• x % 100 -> yield last two digits

Example: Arithmetic operators in Python

Python3

# Examples of Arithmetic Operator
a = 9
b = 4

# Addition of numbers
add = a + b

# Subtraction of numbers
sub = a - b

# Multiplication of number
mul = a * b

# Division(float) of number
div1 = a / b

# Division(floor) of number
div2 = a // b

# Modulo of both number
mod = a % b

# Power
p = a ** b

# print results
print(add)
print(sub)
print(mul)
print(div1)
print(div2)
print(mod)
print(p)

Output

13
5
36
2.25
2
1
6561

Note: Refer to Differences between / and // for some interesting facts about these two operators.

Comparison Operators

Comparison of Relational operators compares the values. It either returns True or False according to the condition.

Operator	Description	Syntax
>	Greater than: True if the left operand is greater than the right	x > y
<	Less than: True if the left operand is less than the right	x < y
==	Equal to: True if both operands are equal	x == y
!=	Not equal to – True if operands are not equal	x != y
>=	Greater than or equal to True if the left operand is greater than or equal to the right	x >= y
<=	Less than or equal to True if the left operand is less than or equal to the right	x <= y
is	x is the same as y	x is y
is not	x is not the same as y	x is not y

= is an assignment operator and == comparison operator.

Example: Comparison Operators in Python

Python3

# Examples of Relational Operators
a = 13
b = 33

# a > b is False
print(a > b)

# a < b is True
print(a < b)

# a == b is False
print(a == b)

# a != b is True
print(a != b)

# a >= b is False
print(a >= b)

# a <= b is True
print(a <= b)

Output

False
True
False
True
False
True

Logical Operators

Logical operators perform Logical AND, Logical OR, and Logical NOT operations. It is used to combine conditional statements.

Operator	Description	Syntax
and	Logical AND: True if both the operands are true	x and y
or	Logical OR: True if either of the operands is true	x or y
not	Logical NOT: True if the operand is false	not x

Example: Logical Operators in Python

Python3

# Examples of Logical Operator
a = True
b = False

# Print a and b is False
print(a and b)

# Print a or b is True
print(a or b)

# Print not a is False
print(not a)

Output

False
True
False

Bitwise Operators

Bitwise operators act on bits and perform the bit-by-bit operations. These are used to operate on binary numbers.

Operator	Description	Syntax
&	Bitwise AND	x & y
|	Bitwise OR	x | y
~	Bitwise NOT	~x
^	Bitwise XOR	x ^ y
>>	Bitwise right shift	x>>
<<	Bitwise left shift	x<<

Example: Bitwise Operators in Python

Python3

# Examples of Bitwise operators
a = 10
b = 4

# Print bitwise AND operation
print(a & b)

# Print bitwise OR operation
print(a | b)

# Print bitwise NOT operation
print(~a)

# print bitwise XOR operation
print(a ^ b)

# print bitwise right shift operation
print(a >> 2)

# print bitwise left shift operation
print(a << 2)

Output

0
14
-11
14
2
40

Assignment Operators 

Assignment operators are used to assign values to the variables.

Operator	Description	Syntax
=	Assign value of right side of expression to left side operand	x = y + z
+=	Add AND: Add right-side operand with left side operand and then assign to left operand	a+=b     a=a+b
-=	Subtract AND: Subtract right operand from left operand and then assign to left operand	a-=b     a=a-b
*=	Multiply AND: Multiply right operand with left operand and then assign to left operand	a*=b     a=a*b
/=	Divide AND: Divide left operand with right operand and then assign to left operand	a/=b     a=a/b
%=	Modulus AND: Takes modulus using left and right operands and assign the result to left operand	a%=b     a=a%b
//=	Divide(floor) AND: Divide left operand with right operand and then assign the value(floor) to left operand	a//=b     a=a//b
**=	Exponent AND: Calculate exponent(raise power) value using operands and assign value to left operand	a**=b     a=a**b
&=	Performs Bitwise AND on operands and assign value to left operand	a&=b     a=a&b
|=	Performs Bitwise OR on operands and assign value to left operand	a|=b     a=a|b
^=	Performs Bitwise xOR on operands and assign value to left operand	a^=b     a=a^b
>>=	Performs Bitwise right shift on operands and assign value to left operand	a>>=b     a=a>>b
<<=	Performs Bitwise left shift on operands and assign value to left operand	a <<= b     a= a << b

Example: Assignment Operators in Python

Python3

# Examples of Assignment Operators
a = 10

# Assign value
b = a
print(b)

# Add and assign value
b += a
print(b)

# Subtract and assign value
b -= a
print(b)

# multiply and assign
b *= a
print(b)

# bitwise lishift operator
b <<= a
print(b)

Output

10
20
10
100
102400

Identity Operators

is and is not are the identity operators both are used to check if two values are located on the same part of the memory. Two variables that are equal do not imply that they are identical. 

is          True if the operands are identical 
is not      True if the operands are not identical 

Example: Identity Operator

Python3

a = 10
b = 20
c = a

print(a is not b)
print(a is c)

Output

True
True

Membership Operators

in and not in are the membership operators; used to test whether a value or variable is in a sequence.

in            True if value is found in the sequence
not in        True if value is not found in the sequence

Example: Membership Operator

Python3

# Python program to illustrate
# not 'in' operator
x = 24
y = 20
list = [10, 20, 30, 40, 50]

if (x not in list):
    print("x is NOT present in given list")
else:
    print("x is present in given list")

if (y in list):
    print("y is present in given list")
else:
    print("y is NOT present in given list")

Output

x is NOT present in given list
y is present in given list

Precedence and Associativity of Operators

Precedence and Associativity of Operators: Operator precedence and associativity determine the priorities of the operator.

Operator Precedence

This is used in an expression with more than one operator with different precedence to determine which operation to perform first.

Example: Operator Precedence

Python3

# Examples of Operator Precedence

# Precedence of '+' & '*'
expr = 10 + 20 * 30
print(expr)

# Precedence of 'or' & 'and'
name = "Alex"
age = 0

if name == "Alex" or name == "John" and age >= 2:
    print("Hello! Welcome.")
else:
    print("Good Bye!!")

Output

610
Hello! Welcome.

Operator Associativity

If an expression contains two or more operators with the same precedence then Operator Associativity is used to determine. It can either be Left to Right or from Right to Left.

Example: Operator Associativity

Python3

# Examples of Operator Associativity

# Left-right associativity
# 100 / 10 * 10 is calculated as
# (100 / 10) * 10 and not
# as 100 / (10 * 10)
print(100 / 10 * 10)

# Left-right associativity
# 5 - 2 + 3 is calculated as
# (5 - 2) + 3 and not
# as 5 - (2 + 3)
print(5 - 2 + 3)

# left-right associativity
print(5 - (2 + 3))

# right-left associativity
# 2 ** 3 ** 2 is calculated as
# 2 ** (3 ** 2) and not
# as (2 ** 3) ** 2
print(2 ** 3 ** 2)

Output

100.0
6
0
512

Quiz on Python Operators

Division Operators allow you to divide two numbers and return a quotient, i.e., the first number or number at the left is divided by the second number or number at the right and returns the quotient. 

There are two types of division operators: 

(i) Float division:

The quotient returns by this operator is always a float number, no matter if two numbers are integer. For example:

>>>5/5
1.0
>>>10/2
5.0
>>>-10/2
-5.0
>>>20.0/2
10.0

(ii) Integer division( Floor division): 

The quotient returned by this operator is dependent on the argument being passed. If any of the numbers is float, it returns output in float. It is also known as Floor division because, if any number is negative, then the output will be floored. For example:

>>>5//5
1
>>>3//2
1
>>>10//3
3

Consider the below statements in Python.

Python3

# A Python program to demonstrate the use of
# "//" for integers
print (5//2)
print (-5//2)

Output:

2
-3

The first output is fine, but the second one may be surprised if we are coming Java/C++ world. In Python, the “//” operator works as a floor division for integer and float arguments. However, the division operator ‘/’ returns always a float value.

Note: The “//” operator is used to return the closest integer value which is less than or equal to a specified expression or value. So from the above code, 5//2 returns 2. You know that 5/2 is 2.5, and the closest integer which is less than or equal is 2[5//2].( it is inverse to the normal maths, in normal maths the value is 3).

Example

Python3

# A Python program to demonstrate use of
# "/" for floating point numbers
print (5.0/2)
print (-5.0/2)

Output

2.5
-2.5

The real floor division operator is “//”. It returns the floor value for both integer and floating-point arguments.

Python3

# A Python program to demonstrate use of
# "//" for both integers and floating points
print (5//2)
print (-5//2)
print (5.0//2)
print (-5.0//2)

Output

2
-3
2.0
-3.0

See this for example. 

Ternary operators

Ternary operators are also known as conditional expressions are operators that evaluate something based on a condition being true or false. It was added to Python in version 2.5. 
It simply allows testing a condition in a single line replacing the multiline if-else making the code compact.

Syntax : 

[on_true] if [expression] else [on_false] 

• Simple Method to use ternary operator:

Python

# Program to demonstrate conditional operator
a, b = 10, 20

# Copy value of a in min if a < b else copy b
min = a if a < b else b

print(min)

Output:

10

• Direct Method by using tuples, Dictionary, and lambda

Python

# Python program to demonstrate ternary operator
a, b = 10, 20

# Use tuple for selecting an item
# (if_test_false,if_test_true)[test]
# if [a<b] is true it return 1, so element with 1 index will print
# else if [a<b] is false it return 0, so element with 0 index will print
print( (b, a) [a < b] )

# Use Dictionary for selecting an item
# if [a < b] is true then value of True key will print
# else if [a<b] is false then value of False key will print
print({True: a, False: b} [a < b])

# lambda is more efficient than above two methods
# because in lambda  we are assure that
# only one expression will be evaluated unlike in
# tuple and Dictionary
print((lambda: b, lambda: a)[a < b]())

Output:

10
10
10

• Ternary operator can be written as nested if-else:

Python

# Python program to demonstrate nested ternary operator
a, b = 10, 20

print ("Both a and b are equal" if a == b else "a is greater than b"
        if a > b else "b is greater than a")

The above approach can be written as: 

Python

# Python program to demonstrate nested ternary operator
a, b = 10, 20

if a != b:
    if a > b:
        print("a is greater than b")
    else:
        print("b is greater than a")
else:
    print("Both a and b are equal")

Output:

 b is greater than a

• To use print function in ternary operator be like:- 

Example: Find the Larger number among 2 using ternary operator in python3

Python3

a=5
b=7

# [statement_on_True] if [condition] else [statement_on_false]

print(a,"is greater") if (a>b) else print(b,"is Greater")

Output:

7 is Greater

Important Points: 

• First the given condition is evaluated (a < b), then either a or b is returned based on the Boolean value returned by the condition
• Order of the arguments in the operator is different from other languages like C/C++ (See C/C++ ternary operators).
• Conditional expressions have the lowest priority amongst all Python operations.

Method used prior to 2.5 when the ternary operator was not present
In an expression like the one given below, the interpreter checks for the expression if this is true then on_true is evaluated, else the on_false is evaluated.

Syntax :

'''When condition becomes true, expression [on_false]
   is not executed and value of "True and [on_true]"
   is returned.  Else value of "False or [on_false]"
   is returned.
   Note that "True and x" is equal to x. 
   And "False or x" is equal to x. '''
[expression] and [on_true] or [on_false] 

Example :

Python

# Program to demonstrate conditional operator
a, b = 10, 20

# If a is less than b, then a is assigned
# else b is assigned (Note : it doesn't
# work if a is 0.
min = a < b and a or b

print(min)

Output:

10

Note : The only drawback of this method is that on_true must not be zero or False. If this happens on_false will be evaluated always. The reason for that is if the expression is true, the interpreter will check for the on_true, if that will be zero or false, that will force the interpreter to check for on_false to give the final result of the whole expression.