Installing Python

Python is available for all major operating systems. The installation process is straightforward and well-documented.

Windows Installation

1. Download the installer from the official website: python.org
2. Run the downloaded .exe file
3. Check "Add Python to PATH" during installation
4. Click "Install Now"
5. Verify installation by opening Command Prompt and typing python --version

macOS Installation

1. Download the macOS installer from the official website
2. Open the downloaded .pkg file
3. Follow the installation prompts
4. Verify installation in Terminal with python3 --version

Linux Installation

Most Linux distributions come with Python pre-installed. To install the latest version:

# For Ubuntu/Debian
sudo apt update
sudo apt install python3

# For Fedora
sudo dnf install python3

# Verify installation
python3 --version

python -m venv myenv

Python Syntax Basics

Python syntax is designed for readability with significant whitespace and minimal punctuation.

Indentation Matters

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

# Correct
if 5 > 2:
    print("Five is greater than two!")

# Incorrect (will cause error)
if 5 > 2:
print("Five is greater than two!")

Comments

Comments start with # and run to the end of the line.

# This is a single-line comment

"""
This is a multi-line comment.
It can span multiple lines.
"""

print("Hello, World!")  # Comment after code

# Your first Python program
print("Hello, World!")

# Simple calculation
result = 5 * 3
print("5 multiplied by 3 is:", result)

# Conditional statement
if result > 10:
    print("Result is greater than 10!")
else:
    print("Result is 10 or less")

Variables & Data Types

Variables are created when you assign a value. Python determines the data type automatically.

Basic Data Types

• Integer (int) - Whole numbers without decimals
• Float (float) - Numbers with decimals
• String (str) - Sequence of characters
• Boolean (bool) - True or False
• List (list) - Ordered, mutable collection
• Tuple (tuple) - Ordered, immutable collection
• Dictionary (dict) - Key-value pairs collection

# Integers
age = 25

# Floats
temperature = 36.6

# Strings
name = "John"

# Booleans
is_student = True

# List
fruits = ["apple", "banana", "orange"]

# Tuple
coordinates = (10.5, 20.3)

# Dictionary
person = {
    "name": "Maria",
    "age": 30,
    "city": "New York"
}

# Working with numbers
x = 10
y = 3.5
sum = x + y
print("Sum:", sum)

# Working with strings
greeting = "Hello, "
name = "Anna"
message = greeting + name
print(message)

# Working with lists
numbers = [1, 2, 3, 4, 5]
numbers.append(6)
print("Number list:", numbers)

# Working with dictionaries
book = {"title": "War and Peace", "author": "Tolstoy", "year": 1869}
print(f"Book: {book['title']}, Author: {book['author']}")

# Type checking
print("Type of x:", type(x))
print("Type of name:", type(name))
print("Type of numbers:", type(numbers))

Conditional Statements

Conditional statements let you execute different code blocks based on conditions.

The if Statement

if condition:
    # execute if condition is true
elif another_condition:
    # execute if first condition is false and this is true
else:
    # execute if all conditions are false

# Determine leap year
year = 2024

if year % 4 == 0:
    if year % 100 == 0:
        if year % 400 == 0:
            print(f"{year} is a leap year")
        else:
            print(f"{year} is not a leap year")
    else:
        print(f"{year} is a leap year")
else:
    print(f"{year} is not a leap year")

# Password check
password = "Python123"
user_input = "python123"

if user_input == password:
    print("Access granted!")
else:
    print("Incorrect password!")

Loops in Python

Loops allow you to execute a block of code repeatedly. Python has two loop types: for and while.

For Loop

Used to iterate over sequences (lists, tuples, strings, etc.).

# Iterate through a list
fruits = ["apple", "banana", "cherry"]
for fruit in fruits:
    print(fruit)

# Iterate through a string
for char in "Python":
    print(char)

# Using range()
for i in range(5):      # 0 to 4
    print(i)

for i in range(2, 6):   # 2 to 5
    print(i)

for i in range(0, 10, 2):  # 0, 2, 4, 6, 8
    print(i)

While Loop

Executes a block of code as long as a condition is true.

# Counter
count = 0
while count < 5:
    print(count)
    count += 1  # equivalent to count = count + 1

# Find prime numbers
print("Prime numbers between 2 and 30:")
for num in range(2, 31):
    is_prime = True
    for i in range(2, num):
        if num % i == 0:
            is_prime = False
            break
    if is_prime:
        print(num, end=" ")

print("\n\nEven numbers from 0 to 10:")
n = 0
while n <= 10:
    if n % 2 != 0:
        n += 1
        continue
    print(n, end=" ")
    n += 1

Functions in Python

Functions allow you to group code for reuse and organization.

Defining Functions

def function_name(parameters):
    """Function documentation (docstring)"""
    # function body
    return result  # optional

# Factorial function
def factorial(n):
    """Calculate factorial of n"""
    if n == 0:
        return 1
    else:
        return n * factorial(n-1)

print("Factorial of 5:", factorial(5))

# Fibonacci function
def fibonacci(n):
    """Return nth Fibonacci number"""
    a, b = 0, 1
    for _ in range(n):
        a, b = b, a + b
    return a

print("First 10 Fibonacci numbers:")
for i in range(10):
    print(fibonacci(i), end=" ")

Learning Resources

Official Documentation

• Python Official Website
• Python Tutorial
• Standard Library Reference

Online Courses

• Python for Everybody (Coursera)
• Codecademy Python Course
• Complete Python Bootcamp (Udemy)

Recommended Books

• Automate the Boring Stuff with Python - Al Sweigart
• Python Crash Course - Eric Matthes
• Fluent Python - Luciano Ramalho

Practice Platforms

• Codewars - Coding challenges
• LeetCode - Algorithm practice
• Project Euler - Math-based problems