Understanding Python Operators: Part 5 🌟

Operator Precedence: The Order of Operations in Python

Python, like mathematics, adheres to specific rules when evaluating expressions. These rules, known as operator precedence, determine the order in which operations are performed. Misunderstanding this hierarchy can lead to subtle errors in your calculations. Let’s dive into how Python processes complex expressions, Boolean logic, and comparison operators.

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🔢 Operator Precedence in Action

Example: Breaking Down a Complex Expression

10 - 4 * 2 + 5 - 6 / 2

Python processes this expression step by step, adhering to operator precedence:

1. Higher Precedence: Multiplication and Division

   10 - 4 * 2 + 5 - 6 / 2

   • Calculate 4 * 2 = 8.

   • Calculate 6 / 2 = 3.0.

   Resulting expression:

   10 - 8 + 5 - 3.0

2. Lower Precedence: Addition and Subtraction (Left to Right)

   • Perform 10 - 8 = 2.

   • Perform 2 + 5 = 7.

   • Perform 7 - 3.0 = 4.0.

   Final result:

   4.0

Key Takeaways:

• Multiplication (*) and division (/) take precedence over addition (+) and subtraction (-).

• Division always returns a float, even if the result is a whole number.

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🧮 The BODMAS Rule in Python

Python’s operator precedence aligns with the BODMAS rule:

1. Brackets: Solve expressions inside parentheses first.

2. Order (Exponents): Handle powers and roots.

3. Division and Multiplication: Process from left to right.

4. Addition and Subtraction: Process from left to right.

Example: Using Brackets to Change Precedence

(10 - 4) * 2 + 5

1. Solve inside the brackets: 10 - 4 = 6.

2. Multiply: 6 * 2 = 12.

3. Add: 12 + 5 = 17.

Without brackets, the multiplication would take precedence over subtraction, leading to a different result.

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✅ Boolean Logic: True or False?

In Python, Boolean operators evaluate whether a given value or expression is True or False.

Truthy and Falsy Values

• Truthy: Non-zero numbers, non-empty strings, and objects.

• Falsy: Zero (0), False, and empty objects (e.g., "", []).

Examples:

bool(1)        # True
bool(0)        # False
bool("")       # False
bool("Python") # True

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Quiz Example:

What is the result of this expression?

bool("")

Answer: False An empty string evaluates to False in Python. Similarly, empty lists ([]), tuples (()), and dictionaries ({}) are also False.

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🔍 Comparison Operators

Comparison operators evaluate relationships between values:

1. Greater than (>)

2. Less than (<)

3. Greater than or equal to (>=)

4. Less than or equal to (<=)

5. Equal to (==)

6. Not equal to (!=)

Examples:

50 > 30   # True
50 <= 50  # True
"abc" == "ABC"  # False (case-sensitive)

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🔄 Assignment vs. Comparison

It’s essential to distinguish between:

• Assignment (=): Assigns a value to a variable.

• Comparison (==): Checks if two values are equal.

Example:

A = 3   # Assignment
A == 3  # Comparison (True)

Mixing these up can lead to bugs. For example:

if A = 3:  # Error! '=' is not a comparison operator
    print("A equals 3")

Correct usage:

if A == 3:  # Correct
    print("A equals 3")

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🧩 Combining Boolean and Comparison Operators

Python allows combining Boolean logic with comparisons:

Example:

A = 10
B = 5

if A > B and B > 0:
    print("A is greater than B, and B is positive")

• and: Both conditions must be True.

• or: At least one condition must be True.

• not: Negates the condition.

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🧪 Test Your Knowledge

1. What is the result of this expression?

   20 / 5 + 3 * 2 - 1

   Answer: 11.0

   • Division and multiplication first: 20/5=4.020 / 5 = 4.0, 3∗2=63 * 2 = 6.

   • Then addition and subtraction: 4.0+6=10.04.0 + 6 = 10.0, 10.0−1=11.010.0 - 1 = 11.0.

2. Evaluate the Boolean logic:

   bool([]) or (5 > 3)

   Answer: True

   • bool([]) is False, but 5 > 3 is True.

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🎯 Key Takeaways

• Python adheres to a clear operator precedence, simplifying complex expressions with the BODMAS rule.

• Understand the difference between assignment (=) and comparison (==) to avoid common errors.

• Boolean operators help you build more powerful decision-making logic.

Stay tuned for Part 6, where we’ll explore Python’s logical operators and their practical applications! 😊