CHAPTER 05 · CONTROL-FLOW5 min read

Logical operators: and, or, not

Real-world rules often require checking multiple conditions at once: 'You must be at least 120cm tall AND have a ticket, OR be accompanied by an adult.' Logical operators make this possible.

By the end of this chapter, you can:

Combine conditions using the 'and' operator (both must be True).
Use the 'or' operator (at least one must be True).
Invert conditions cleanly using the 'not' operator.

Explanation DepthTailor the level of detail to your learning goal

💻 Standard College Notes

Boolean algebra with and, or, not, and operator precedence.

Logical operators combine multiple conditions. Precedence order: not takes precedence over and, which takes precedence over or. Use parentheses to eliminate ambiguity.

💡A and B is True only when both are True; A or B is True when at least one is True.

Roller-Coaster ticketing logic

You can only ride if height >= 120cm. Ticket price depends on age: child (<12: $5), youth (12-18: $7), adult (>18: $12). Plus an optional photo pass for $3.

height = 135
age = 16
wants_photo = True

if height >= 120:
    if age < 12:
        bill = 5
    elif age <= 18:
        bill = 7
    else:
        bill = 12

    if wants_photo:
        bill = bill + 3

    print(f"Eligible! Your total ticket bill is: ${bill}")
else:
    print("Sorry, you must grow taller before riding.")

Terminal Output

Ready to execute

Click "▶ Run Code" or press Ctrl+Enter to compile & run this snippet.

✦ Interactive Dry-Run Visualizer

Memory Trace: Multi-Tier Condition Evaluation

Step through height validation, age price bracket, and photo surcharge.

STEP1 / 7

1height = 135👉 Executing

2age = 16

3bill = 0

4if height >= 120:

5 bill = 7

6bill = bill + 3

7print(bill)

🧠 RAM / Variable Memory State

Variable	Value in Memory	Data Type
height	135	int

Initialize rider height

135cm stored.

Console Stream (stdout)

(No output generated yet)

Line 1: height = 135

🔧 Missing Parentheses in Logic Precedence

A rollercoaster admission check let riders in without a pass because OR evaluated with unexpected precedence.

⚡ +100 XP

fix_bug.pyPython 3.10

⚡ Quick Revision Quiz

Predict The Output (2 Questions)

Question 1 of 2:

What does False or True and False evaluate to?

Question 2 of 2:

What is the output of: not (10 > 5)?

Your lightbulb moment

✧

The key takeaway
`and`, `or`, and `not` allow compounding logical conditions to model real-world business and game rules.

Make it yours

Try changing the age to 25 and rerun to verify that the adult tier ($12 + $3 = $15) runs automatically.

Try editing the code in the playground above in Python, JavaScript, Java, or C++, and use the step-by-step Dry-Run Table to inspect how variables mutate in memory. If you get stuck, click the 🤖 AI Doubt Solver button on your screen for instant explanations!