Python Operator Precedence and Associativity

When several operators appear together in a Python expression, the interpreter first compares their precedence and evaluates them from highest to lowest; operators with the same precedence are then resolved according to their associativity (left‑to‑right or right‑to‑left).

For example, in the arithmetic expression 2 + 4 * 3 , multiplication has higher precedence than addition, so the multiplication is performed first.

Python's operator precedence hierarchy (from highest to lowest) includes:

Parentheses ()

Exponentiation **

Unary plus/minus and bitwise NOT ~

Multiplication, division, floor division, modulo * / // %

Addition and subtraction + -

Bitwise shifts > <<

Bitwise AND &

Bitwise XOR and OR ^ |

Comparison operators < <= > >=

Equality operators == !=

Assignment operators = %= /= //= -= += *= **=

Identity operators is / is not

Membership operators in / not in

Logical operators and / or / not

Associativity determines the order when operators share the same precedence. Most operators are left‑associative, meaning evaluation proceeds from the left; exponentiation ** , unary signs, and assignment operators are right‑associative.

<code>>> 5 / 2 * 4  # left‑associative operators
10.0
>>> 2 ** 2 ** 3  # right‑associative, equivalent to 2 ** (2 ** 3)
256
</code>

Although Python follows these rules, writing overly long or complex expressions is discouraged because it harms readability. The article recommends two best practices: keep expressions short or split them into simpler parts, and use parentheses liberally to make evaluation order explicit.

Author: Liu Wenfei