Basic Syntax

Master Python's fundamental syntax rules including indentation, variables, comments, and code structure

🔤 Indentation

Python uses indentation instead of curly braces {} to define code blocks.

Think of it like this: Just like you indent paragraphs in a letter, Python uses indentation to show which code belongs together.

# Correct indentation - code inside the if block
if True:
    print("This is indented")
    print("This is also indented")
    print("All these lines belong to the if block")

print("This line is outside the if block")

# Expected output:
# This is indented
# This is also indented
# All these lines belong to the if block
# This line is outside the if block

Rules for Indentation

• Use 4 spaces per indentation level
• Be consistent throughout your code
• Don't mix tabs and spaces

💬 Comments

Single-line Comments:

# This is a comment
print("Hello, World!")  # This is also a comment

Multi-line Comments (Docstrings):

"""
This is a multi-line comment
or docstring. It's often used
for function documentation.
"""

def my_function():
    """
    This function does something amazing.
    """
    pass

📝 Variables and Data Types

Creating Variables:

# Variables are created when you assign a value
name = "Alice"
age = 25
height = 5.6
is_student = True

Variable Naming Rules:

• Must start with a letter or underscore
• Can contain letters, numbers, and underscores
• Case-sensitive (name and Name are different)
• Cannot use Python keywords

# Valid variable names
user_name = "John"
age2 = 30
_private = "secret"

# Invalid variable names
# 2age = 30        # Cannot start with number
# user-name = "John"  # Cannot contain hyphens
# class = "Python"    # Cannot use keywords

🎯 Python Keywords

Python has reserved words that cannot be used as variable names:

# Common keywords
and, or, not, if, else, elif, for, while, def, class, 
import, from, as, try, except, finally, with, lambda, 
return, pass, break, continue, True, False, None

📊 Basic Data Types

# String
name = "Python"
message = 'Hello, World!'

# Integer
age = 25
count = 0

# Float
price = 19.99
temperature = -5.5

# Boolean
is_active = True
is_complete = False

# None (represents absence of value)
result = None

🔍 Checking Types

name = "Alice"
age = 25

print(type(name))   # <class 'str'>
print(type(age))    # <class 'int'>

🚀 Practice Exercise

Try this simple program:

# Personal information
first_name = "John"
last_name = "Doe"
age = 30
is_programmer = True

# Print information
print("Name:", first_name, last_name)
print("Age:", age)
print("Is programmer:", is_programmer)

🎯 Key Takeaways

• Python uses indentation to define code structure
• Use 4 spaces for indentation
• Comments start with # or use """ for multi-line
• Variables are created by assignment
• Python is case-sensitive
• Follow naming conventions for readable code

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