Fundamentals of Operator Precedence in Python
What is Operator Precedence?
Operator precedence in Python refers to the order in which operators are evaluated when an expression contains multiple operators. It determines the sequence in which operations are performed, ensuring that the expression is evaluated correctly and produces the expected result.
Understanding Operator Associativity
Operator associativity determines the direction in which operators of the same precedence are evaluated. In Python, most operators are left-associative, meaning that they are evaluated from left to right. However, some operators, such as the exponentiation operator (**), are right-associative.
Operator Precedence Table
The following table outlines the precedence of various operators in Python, from highest to lowest:
| Operator | Description |
| ---------------------------------------------------------------- | ------------------------------------------------ | ---------- |
| ()
| Parentheses |
| **
| Exponentiation |
| +x
, -x
, ~x
| Unary operators (plus, minus, bitwise NOT) |
| *
, /
, //
, %
| Multiplication, division, floor division, modulo |
| +
, -
| Addition, subtraction |
| <<
, >>
| Bitwise left and right shift |
| &
| Bitwise AND |
| ^
| Bitwise XOR |
| |
| Bitwise OR |
| ==
, !=
, >
, <
, >=
, <=
, is
, is not
, in
, not in
| Comparison operators |
| not
| Boolean NOT |
| and
| Boolean AND |
| or
| Boolean OR |
Operator Precedence in Action
Let's look at an example to understand how operator precedence works in Python:
result = 2 + 3 * 4 ** 2 - 1
In this expression, the exponentiation operator (*) has the highest precedence, followed by multiplication (), then addition (+), and finally subtraction (-). The expression is evaluated as follows:
4 ** 2 = 16
3 * 16 = 48
2 + 48 = 50
50 - 1 = 49
Therefore, the final result of the expression is 49
.
graph TD
A[2 + 3 * 4 ** 2 - 1] --> B[4 ** 2 = 16]
B --> C[3 * 16 = 48]
C --> D[2 + 48 = 50]
D --> E[50 - 1 = 49]
E[Final result: 49]
By understanding the fundamentals of operator precedence, you can write more complex expressions in Python and ensure that they are evaluated correctly.