Python Syntax & Variables Indentation, Comments, Variables, Naming Conventions

Python Basics: Syntax & Variables

Learn the ABCs of Python coding – indentation, comments, variables, and naming rules!

1. Python Syntax: The Rules of the Game

Syntax means the set of rules that define how to write Python code. Think of it like grammar for programming!

Indentation: Spaces Matter!

In Python, indentation (spaces or tabs) is used to group code blocks, like loops or conditions.

age = 12
if age >= 10:
    print("You can join the coding club!")  # Indented with 4 spaces
else:
    print("Keep practicing!")

✅ Correct: Lines under if and else are indented.

❌ Wrong: No indentation → Python throws an error!

Pro Tip: Use 4 spaces (not tabs) for indentation. Most editors do this automatically!

2. Comments: Notes for Humans

Comments are notes you add to explain your code. Python ignores them!

Single-Line Comments

Use # to write a comment:

# This program calculates your age
current_year = 2024
birth_year = 2012
age = current_year - birth_year
print(age)  # Output: 12

Multi-Line Comments

Use triple quotes """ for longer notes:

"""
This program greets a user.
Author: Coding Champ
Date: 2024
"""
name = "Alex"
print("Hello, " + name)

3. Variables: Your Data Containers

A variable is like a labeled lunchbox that stores data (numbers, text, etc.).

Creating Variables

Assign values with =:

school = "Sunrise Middle School"  # Stores text (string)
students = 250                    # Stores number (integer)
is_fun = True                     # Stores True/False (boolean)

Example:

# Calculate total candies
candies_per_student = 5
total_students = 30
total_candies = candies_per_student * total_students
print("We need", total_candies, "candies!")  # Output: We need 150 candies!

4. Naming Conventions: Rules for Variable Names

Python has rules for naming variables:

Rule	✅ Valid	❌ Invalid
Start with a letter or _	score, _player	3rd_place
Use letters, numbers, or _	game_level2	total-score
Case-sensitive	HighScore ≠ highscore
Use descriptive names	student_age	sa

Examples:

# Good names:
player_health = 100
max_speed = 5.8

# Bad names:
a = 10  # What does 'a' mean?
xYz = "Hi"  # Confusing uppercase/lowercase

Pro Tip: Use snake_case (all lowercase with underscores) for variable names, like favorite_color.

Fun Practice: Story Generator

Let’s use variables to make a silly story!

# Fill in the blanks
adjective = "spooky"
animal = "penguin"
verb = "dance"

story = f"Once, a {adjective} {animal} loved to {verb} in class!"
print(story)

Output:

Once, a spooky penguin loved to dance in class!

Troubleshooting Tips

• ❌ SyntaxError: invalid syntax: Check for missing : or wrong indentation.
• ❌ NameError: variable not defined: Did you spell the variable name correctly?
• ❌ TypeError: Mixing data types? E.g., print("Age: " + 12) → Fix: print("Age: " + str(12)).

Key Takeaways

• ✅ Indentation groups code blocks (use 4 spaces!).
• ✅ Comments explain your code with # or """
• ✅ Variables store data (text, numbers, True/False).
• ✅ Naming rules: Start with letters/_, use snake_case, and be descriptive!

What’s Next?

Practice with this mini-quiz!

# Fix the errors in this code:
school_name = "Maple Middle School"
number_of_students = 300
print("Welcome to " + school_name)
print("We have " + number_of_students + " students!")

Hint: Look at the data types!

Pro Tip: Experiment by changing variable values and see what happens! Coding is all about trial and error. 🚀

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