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Operator precedence in python with examples

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

OperatorDescription
** Exponentiation [raise to the power]
~ + - Complement, unary plus and minus [method names for the last two are +@ and -@]
* / % // Multiply, divide, modulo and floor division
+ - Addition and subtraction
>>
^ | Bitwise exclusive `OR' and regular `OR'
>= Comparison operators
== != Equality operators
= %= /= //= -= += *= **= Assignment operators
is is not Identity operators
in not in Membership operators
not or and Logical operators

Operator precedence affects how an expression is evaluated.

For example, x = 7 + 3 * 2; here, x is assigned 13, not 20 because operator * has higher precedence than +, so it first multiplies 3*2 and then adds into 7.

Here, operators with the highest precedence appear at the top of the table, those with the lowest appear at the bottom.

Example

#!/usr/bin/python

a = 20
b = 10
c = 15
d = 5
e = 0

e = [a + b] * c / d       #[ 30 * 15 ] / 5
print "Value of [a + b] * c / d is ",  e

e = [[a + b] * c] / d     # [30 * 15 ] / 5
print "Value of [[a + b] * c] / d is ",  e

e = [a + b] * [c / d];    # [30] * [15/5]
print "Value of [a + b] * [c / d] is ",  e

e = a + [b * c] / d;      #  20 + [150/5]
print "Value of a + [b * c] / d is ",  e

When you execute the above program, it produces the following result −

Value of [a + b] * c / d is 90
Value of [[a + b] * c] / d is 90
Value of [a + b] * [c / d] is 90
Value of a + [b * c] / d is 50

python_basic_operators.htm

Onyejiaku Theophilus Chidalu

Overview

Operator precedence in Python simply refers to the order of operations. Operators are used to perform operations on variables and values.

Python classifies its operators in the following groups:

  • Arithmetic operators
  • Assignment operators
  • Comparison operators
  • Logical/Bitwise operators
  • Identity operators
  • Membership operators

Arithmetic Operators

Common arithmetic operators in Python include:

  • Addition +
  • Subtraction -
  • Multiplication *
  • Division/modulus /or//
  • Exponentiation **
  • Brackets/Parenthesis []

Order of operations

The order of operations of the arithmetic operators can be remembered using the acronym BEDMAS.

The acronym stands for the following words, which tell us which operator comes first:

  • B= Bracket
  • E = Exponentiation
  • D = Division
  • M = Multiplication
  • A = Addition
  • S = Subtraction

Through the acronym, we can see that the bracket/parenthesis operator comes before the exponentiation operation in Python, according to the order of operations.

The same logic applies to each of the following operators, down to the subtraction operator.

Example

To fully grasp BEDMAS and the order of preference of the operators, let’s take a look at the example below:

X = [5 + 3] * 2 ** 2
print[X]

From this program, we can see that there are three operators:

  • Bracket [B]
  • Exponentiation [E]
  • Multiplication [M]

According to operator precedence, Python first deals with the numbers in the bracket operator [B]: [5 + 3] = 8.

We then proceed to the exponentiation operator [E]: 2 ** 2 = 4.

Finally, the results of both the bracket [8] and exponentiation [4] operators are then executed using the multiplication operator [M]: 8 * 4 = 32.

In short, Python followed the order of operators outlined in BEDMAS.

Example

The same logic applies to the examples below:

x = 3 + 8 * 2** 3
print[x]
y= [4 * 2] + 6 / 3 - 2
print[y]

The value of x in the example above follows E,M,A order of operations while the value of y follows B,D,S order.

Assignment Operators

Common assignment operators in Python include:

  • Assign operator =
  • Add AND operator+=
  • Subtract AND operator -=
  • Multiply AND operator *=
  • Divide AND operator /=
  • Modulo AND operator %=
  • Exponent AND operator **=

Order of operation

Since these operators are not associative, there is no order of operation for them. They are always performed or declared exclusively.

Example

# using the assigm operator 
x = 6
y = 2 
# to generate the Add AND operator i.e  x + y = 8
x += y
print[x] 
# to generate the subtract AND operator i.e x - y = 8 - 2 = 6  
x -= y 
print[x]
# to generate the multiply AND ooperator i.e x * y = 6 * 2 = 12
x *= y 
print[x]
# to generate the divide AND operator i.e x / 2 = 12 / 2 = 6  
x /= y 
print[x]
# to generate the modulo AND operator 1.e x %= 2 = 6 % 2 = 0
x %= y
print[x]

Comparison Operators

Comparison operators include: