Python Operators

Groups of Operators in Python

• Python categorizes operators into arithmetic, assignment, comparison, logical, bitwise, identity, and membership groups.

Arithmetic Operators

• Arithmetic operators perform common mathematical operations using numeric values.
• Addition: x + y
• Subtraction: x - y
• Multiplication: x * y
• Division: x / y
• Modulus: x % y (returns the division remainder)
• Floor division: x // y (returns the division quotient)
• Exponentiation: x ** y

Assignment Operators

• Assignment operators assign values to variables.
• Assignment: x = y
• Addition Assignment: x += y (same as x = x + y)
• Subtraction Assignment: x -= y (same as x = x - y)
• Multiplication Assignment: x *= y (same as x = x * y)
• Division Assignment: x /= y (same as x = x / y)
• Modulus Assignment: x %= y (same as x = x % y)
• Floor Division Assignment: x //= y (same as x = x // y)
• Exponentiation Assignment: x **= y (same as x = x ** y)

Comparison Operators

• Comparison operators determine equality or difference between variables or values in logical statements.
• They test for true or false.
• Equal: x == y
• Not equal: x != y
• Greater than: x > y
• Less than: x < y
• Greater than or equal to: x >= y
• Less than or equal to: x <= y

Logical Operators

• Logical operators determine logic between variables or values.
• and: Returns True if both statements are true.
• or: Returns True if one of the statements is true.
• not: Reverses the result; returns False if the result is true.

Bitwise Operators

• Bitwise operators compare binary numbers.
• Operations are performed on 32-bit binary numbers and then converted back to Python numbers.
• & (AND): Sets each bit to 1 if both bits are 1. Example: 5 & 1 (0101 & 0001 = 0001), which results in 1.
• | (OR): Sets each bit to 1 if one of two bits is 1. Example: 5 | 1 (0101 | 0001 = 0101), which results in 5.
• ^ (XOR): Sets each bit to 1 if only one of two bits is 1. Example: 5 ^ 1 (0101 ^ 0001 = 0100), which results in 4.
• ~ (NOT): Inverts all the bits. Example: ~5 (~0101 = 1010), resulting in 10.
• << (left shift): Shifts left by pushing zeros in from the right; leftmost bits fall off. Example: 5 << 1 (0101 << 1 = 1010), which results in 10.
• >> (right shift): Shifts right by pushing copies of the leftmost bit in from the left; rightmost bits fall off. Example: 5 >> 1 (0101 >> 1 = 0010), which results in 2.

Identity Operators

• Identity operators compare objects to see if they are the same object with the same memory location.
• is: Returns True if both variables are the same object.
• is not: Returns True if both variables are not the same object.
• Variables x and y are distinct even if they have identical contents. The is operator returns False. The overloaded equality operator== would return True for the same test.

Membership Operators

• Membership operators test if a sequence is present in an object.
• in: Returns True if a sequence with the specified value is present in the object.
• not in: Returns True if a sequence with the specified value is not present in the object.

Operator Precedence

• Operator precedence determines the order in which operations are performed.
• Multiplication (*) and division (/) have higher precedence than addition (+) and subtraction (-).
• Parentheses have the highest precedence and are always evaluated first.
• Operators with the same precedence are computed from left to right.
• From highest to lowest precedence: Parentheses, Exponentiation, Unary plus/minus/bitwise NOT, Multiplication/division/floor division/modulus, Addition/subtraction, Bitwise shifts, Bitwise AND, Bitwise XOR, Bitwise OR, Comparison/identity/membership operators, Logical NOT, Logical AND, Logical OR.

Python Booleans

• Booleans represent one of two values: True or False.
• Any expression in Python can be evaluated and will return either True or False.
• When comparing two values, the expression is evaluated, and Python returns a Boolean answer.
• The bool() function evaluates any value and returns True or False.
• Almost any value is evaluated to True if it has some sort of content.
• Any string is True, except empty strings.
• Any number is True, except 0.
• Any list, tuple, set, and dictionary are True, except empty ones.

Python Exercises

• Division operator (/) divides numbers.
• Modulus operator (%) returns the division remainder.
• Floor division (//) returns the division quotient.
• Arithmetic assignment operators are a shorthand way of performing arithmetic operations.
• The << operator inserts the specified number of 0s from the right and lets the same amount of leftmost bits fall off.
• Bitwise right shift has a lower precedence than subtraction.