Day 3: Conditions & Loops - One Week Python

📚 What You'll Learn Today

Today you'll learn how to make your programs make decisions and repeat actions:

Conditional statements (if, elif, else)
Comparison operators
Boolean logic (and, or, not)
While loops and for loops

🎯 Interactive Number Guesser

Try this Python-powered number guessing game! It uses exactly what you'll learn today:

🔧 Python Concepts in Action:

🔀 If/Else Statements Compares your guess to the secret number

🔄 While Loops Keeps asking until you guess correctly

📊 Boolean Logic True/False conditions control the game

🎮 User Input Handles your guesses and validates input

🖥️ Open Full Screen Demo

🔀 If Statements

Use if statements to execute code only when certain conditions are true.

Basic Syntax:

if condition:
    # This code runs if condition is True
    print("This happens!")
            

With else:

age = 18

if age >= 18:
    print("You can vote!")
else:
    print("You're too young to vote.")
            

You can vote!

With elif (else if):

score = 85

if score >= 90:
    print("Grade: A")
elif score >= 80:
    print("Grade: B")
elif score >= 70:
    print("Grade: C")
else:
    print("Grade: F")
            

Grade: B

💡 Remember: Python uses indentation (spaces at the start of lines) to define code blocks. Use 4 spaces per level!

⚖️ Comparison Operators

Compare values using these operators:

Operator	Meaning	Example	Result
==	Equal to	`5 == 5`	True
!=	Not equal to	`5 != 3`	True
>	Greater than	`5 > 3`	True
<	Less than	`3 < 5`	True
>=	Greater than or equal	`5 >= 5`	True
<=	Less than or equal	`3 <= 5`	True

⚠️ Important: Use == to compare, not =. = is for assignment, == is for comparison.

🔗 Boolean Logic

Combine conditions using and, or, and not.

and - Both must be true:

age = 25
has_license = True

if age >= 21 and has_license:
    print("You can drive!")
else:
    print("You cannot drive.")
            

You can drive!

or - At least one must be true:

day = "Saturday"

if day == "Saturday" or day == "Sunday":
    print("It's the weekend!")
else:
    print("It's a weekday.")
            

It's the weekend!

not - Reverses the condition:

is_raining = False

if not is_raining:
    print("No rain - go outside!")
else:
    print("Bring an umbrella!")
            

No rain - go outside!

🔄 While Loops

Repeat code while a condition is true.

Basic while loop:

count = 1

while count <= 5:
    print("Count:", count)
    count += 1  # Same as: count = count + 1

print("Blast off!")
            

Count: 1 Count: 2 Count: 3 Count: 4 Count: 5 Blast off!

⚠️ Warning: Be careful with while loops! If the condition never becomes False, the loop will run forever. Press Ctrl+C to stop it.

📊 For Loops

Loop through a sequence (like a list or range).

Using range():

# range(5) gives: 0, 1, 2, 3, 4
for i in range(5):
    print("Number:", i)
            

Number: 0 Number: 1 Number: 2 Number: 3 Number: 4

With start and end:

# range(1, 6) gives: 1, 2, 3, 4, 5
for i in range(1, 6):
    print("Number:", i)
            

Number: 1 Number: 2 Number: 3 Number: 4 Number: 5

Looping through a list:

colors = ["red", "green", "blue"]

for color in colors:
    print("Color:", color)
            

Color: red Color: green Color: blue

🛠️ Step-by-Step Building Guide

Follow these steps to build your own number guessing game:

Step 1: Import Required Libraries

# number_guesser.py - Start with imports
import random

def main():
    """Main game function"""
    secret_number = random.randint(1, 100)
    guess = 0
    attempts = 0
    
    print("🎯 Number Guessing Game")
    print("I'm thinking of a number between 1-100")
    
    while guess != secret_number:
        guess = int(input("Enter your guess: "))
        attempts += 1
        
        if guess < secret_number:
            print("Too low! Try higher.")
        elif guess > secret_number:
            print("Too high! Try lower.")
    
    print(f"🎉 Correct! Got it in {attempts} tries!")

if __name__ == "__main__":
    main()
            

Step 2: Add Input Validation

def get_valid_guess():
    """Get and validate user input"""
    while True:
        try:
            guess = int(input("Enter guess (1-100): "))
            if 1 <= guess <= 100:
                return guess
            print("Please enter 1-100!")
        except ValueError:
            print("Please enter a valid number!")
            

Step 3: Add Game Loop with Attempts Counter

def play_game():
    secret_number = random.randint(1, 100)
    attempts = 0
    max_attempts = 10
    
    print(f"🎯 Guess the number (1-100) in {max_attempts} tries!")
    
    while attempts < max_attempts:
        attempts += 1
        guess = get_valid_guess()
        
        if guess == secret_number:
            print(f"🎉 Got it in {attempts} tries!")
            return
        
        if guess < secret_number:
            print("🔺 Too low!")
        else:
            print("🔻 Too high!")
    
    print(f"💥 Game Over! The number was {secret_number}")
            

Step 4: Add Hint System

def get_hint(secret_number, attempts, max_attempts):
    """Provide strategic hints"""
    remaining = max_attempts - attempts
    
    if remaining <= 2:
        return f"Very close! Only {remaining} tries left!"
    elif attempts >= 3:
        if secret_number > 50:
            return "The number is higher than 50"
        else:
            return "The number is lower than 50"
    
    return "Keep trying!"
            

🎯 Key concepts you're learning:

while loops - Keep going until condition is met
if/elif/else - Make decisions based on conditions
boolean logic - True/False conditions control flow
input validation - Handle user errors gracefully
random numbers - Generate unpredictable values

🏋️ Exercise: Number Guessing Game

Create a program where the computer picks a random number and you have to guess it!

# Here's a starter - complete the logic:
secret_number = 7
guess = 0

# Ask for user input and check if guess is correct
# Tell them if their guess is too high or too low
# Keep asking until they get it right!
            

Bonus Challenge:

Count how many guesses it took and print "You got it in X guesses!"

# Example solution:
secret_number = 7
guess = 0
attempts = 0

while guess != secret_number:
    guess = int(input("Guess a number: "))
    attempts += 1
    
    if guess < secret_number:
        print("Too low!")
    elif guess > secret_number:
        print("Too high!")
    else:
        print("You got it!")

print("Guesses:", attempts)
            

✅ Key Takeaways

if runs code when condition is True
elif adds more conditions
else runs when no conditions match
== compares, = assigns
and, or, not combine conditions
while loops while condition is True
for loops through sequences
range(n) creates numbers 0 to n-1

🎉 Ready for Day 4?

Tomorrow you'll learn about functions - writing reusable code!

Marking complete will unlock Day 4!

🔀 Day 3: Conditions & Loops

📚 What You'll Learn Today

🎯 Interactive Number Guesser

🔧 Python Concepts in Action:

🔀 If Statements

Basic Syntax:

With else:

With elif (else if):

⚖️ Comparison Operators

🔗 Boolean Logic

and - Both must be true:

or - At least one must be true:

not - Reverses the condition:

🔄 While Loops

Basic while loop:

📊 For Loops

Using range():

With start and end:

Looping through a list:

🛠️ Step-by-Step Building Guide

Step 1: Import Required Libraries

Step 2: Add Input Validation

Step 3: Add Game Loop with Attempts Counter

Step 4: Add Hint System

🏋️ Exercise: Number Guessing Game

Bonus Challenge:

✅ Key Takeaways

🎉 Ready for Day 4?