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.

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

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