Code Labs: Defensive Design

Master Authentication checks and Validation trap loops.

Interactive Engine

Test simple validation routines below. Try breaking it purposefully!

loop_demo.py

# A standard length check validation trap
username = input("Enter a 5-letter name: ")

# The trap starts here
while len(username) != 5:
    print("Invalid! Length must be exactly 5.")
    # Re-ask the question inside the loop
    username = input("Enter a 5-letter name: ")
    
print("Valid username accepted.")

Console Output

> Waiting to compile...

The Crucible

Prove your knowledge of authentication logic and validation boundaries.

Bronze (Authentication)

The Gatekeeper

Authentication just confirms identity. Usually utilizing a simple conditional check.

Task: Finish the if/else statement to only print "Access Granted!" if the provided password variable precisely equals "Dragon".

bronze.py

password = input("Enter password: ")

# Add the 'if' condition below:
???
    print("Access Granted!")
# Add the 'else' condition below:
???
    print("Access Denied!")

> Output will appear here...

Silver (Range Trap)

Trapping Outliers

A teenager account needs an age between 13 and 19 inclusive. We use `or` to check if they entered something outside that bound.

Task: Fix the missing while loop statement to correctly trap users who enter an age less than 13 OR greater than 19. E.g. while age < 13 or age > 19:

silver.py

age = int(input("Enter an age between 13 and 19: "))

# Complete the While Loop trap condition
???
    print("Invalid age!")
    age = int(input("Enter an age between 13 and 19: "))
    
print("Age accepted!")

> Output will appear here...

Gold (Length Validation)

Impenetrable Defence

Passwords are strings. To check how many characters a string has, we wrap it in the len() command (e.g. len(password)).

Task: Create a full validation loop condition that keeps asking the user for a password as long as the length is strictly less than 8 characters.

gold.py

password = input("Create a password (min 8 chars): ")

# Add the while loop assessing the length here
# while ...
    print("Password too short.")
    password = input("Create a password (min 8 chars): ")

print("Password is secure.")

> Output will appear here...

Return to Theory Guide

Interactive Engine

User Input Required

The Gatekeeper

Trapping Outliers

Impenetrable Defence