Tutorial 6/15 Making Decisions

Python: Complex Logic

Master and, or, and elif ladders for sophisticated control flow.

The Hook

Sometimes one check isn't enough.
Think of a VIP Club Bouncer.

To enter, you need ID AND a Ticket. (Both must be True)
To win a prize, you need a Red Ticket OR Blue Ticket. (Only one needed)

Check
ID Card

Check
Valid Ticket

Worked Example

We use and, or, and elif (else if) for complex choices.

age = 16

has_ticket = True

if age >= 18 and has_ticket:

# Both need to be True

print("Enter VIP")

elif has_ticket:

# Runs only if first check failed

print("Enter Regular")

else:

# If nothing else worked

print("Go Home")

Trap 1: The Lazy IF

Wrong: if x > 5 and < 10:

Python forgets the variable "x" in the second check!

Fixed: if x > 5 and x < 10:

Trap 2: The Negative OR

Issue: if color != "Red" or color != "Blue":

This is ALWAYS True! (If Red, it's not Blue).

Safe: if color != "Red" and color != "Blue":

Active Recall

Predict Logic

If score is 50, what exactly prints?

if score > 80:
  print("Gold")
elif score > 40:
  print("Silver")
else:
  print("Bronze")

Complex Sandbox

Production Logic Simulator

main.py

temp = 35
sunny = True

if temp > 30 and sunny == True:
    print("Beach Time!")
elif temp < 10:
    print("Wear a coat")
else:
    print("Just a normal day")

Terminal_

> Logic Layer Ready...

Level 13: Bronze

Rollercoaster

"Change the height requirement to 140. Run it to see if you can still ride."

height = 135
age = 12
if height > 120 and age >= 10:
    print("You can ride")

> bronze_stdout_ready

Level 14: Silver

Lazy Logic Fix

"Python forgets 'num' in the second part of the check. Fix the syntax error: and < 20."

num = 15
# Fix this line:
if num > 10 and < 20: 
    print("In range")

> debugger_standby

Level 15: Gold

Secure Login

"Ask for user and password. Print 'Access Granted' ONLY if both 'admin' and '1234' are correct."

> security_module_idle

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