Operators and Precedence Rules

1
5Кб

In Python, operators are special symbols that perform operations on operands (values or variables). Operator precedence determines the order in which these operations are evaluated within an expression. Understanding precedence is essential for writing correct and predictable code.

Precedence Levels:

Python follows the PEMDAS (or BODMAS) order of operations, just like basic math. Here's a breakdown from highest to lowest precedence:

  1. Parentheses (): Expressions within parentheses are evaluated first. You can use parentheses to override the default order or to group subexpressions.
  2. Exponentiation **: This operator performs powers or exponentiation. For example, 2 ** 3 equals 8.
  3. Multiplication and Division (*, /, %): These operators have equal precedence. Multiplication and division are evaluated from left to right. The modulo operator (%) calculates the remainder after a division.
  4. Addition and Subtraction (+, -): Similar to multiplication and division, these operators have equal precedence and are evaluated left to right.

Example:

Python
expression = 2 + 3 * 4 - (10 / 2) ** 2

Following PEMDAS:

  1. Evaluate the expression within parentheses first: (10 / 2) ** 2 = 5 ** 2 = 25
  2. Perform exponentiation: 2 + 3 * 4 - 25
  3. Multiplication: 2 + 12 - 25
  4. Left-to-right addition and subtraction: -11

Associativity:

When multiple operators have the same precedence level, associativity determines the direction of evaluation (left to right or right to left). Almost all operators in Python are left-associative, meaning they are evaluated from left to right. However, the exponentiation operator (**) is an exception - it's right-associative.

Example:

Python
expression = 2 ** 3 ** 2  # Right associativity for **

This is evaluated as 2 ** (3 ** 2), which equals 2 ** 9 or 512.

Tips for Using Operators:

  • Use parentheses liberally to improve code readability and enforce the desired evaluation order, especially in complex expressions.
  • Be mindful of the precedence and associativity rules to avoid unexpected results.
  • If the order of evaluation is unclear, break down the expression into smaller steps or use parentheses for clarity.
Like
2
Поиск
Категории
Больше
Business
How to Start Selling on Amazon FBA: A Step-by-Step Guide
Are you looking to tap into the booming world of e-commerce? Selling on Amazon using Fulfillment...
От Patswe 2024-09-18 20:21:05 0 5Кб
Computer Programming
Keywords, Multiple Output, and Documentation
1. Keywords: Keywords are reserved words in Python that have special meanings. They cannot...
Technology
Understanding the SUMPRODUCT Function
The SUMPRODUCT function in Excel is a powerful tool used to perform array-based calculations...
От Microsoft Excel 2024-09-03 03:25:02 0 6Кб
Computer Programming
Types Summary and Type Conversion
Types summary The following is a summary of the different Python types: string -...
Chemistry
NEW CURRICULUM CHEMISTRY PRACTICAL SAMPLES
https://acrobat.adobe.com/id/urn:aaid:sc:EU:4838a935-5393-417a-a9b9-a4c21d6109cb
От Expedito 2024-07-18 19:33:23 0 5Кб