Chapter 1: Python Basics

Introduction to Python

Python is a high-level, interpreted programming language created by Guido van Rossum and first released in 1991. It emphasizes code readability with its notable use of significant whitespace.

Why Python?

Python has become one of the most popular programming languages because it is:

• Easy to learn: Clean syntax and readability make it accessible to beginners
• Versatile: Used in web development, data science, AI, scientific computing, and more
• Powerful: Extensive standard library and third-party packages
• Cross-platform: Runs on Windows, macOS, Linux, and many other platforms

Setting Up Python

To get started with Python, you need to install it on your computer:

1. Visit python.org
2. Download the latest version for your operating system
3. Run the installer and follow the instructions

Your First Python Program

Let’s create the traditional “Hello, World!” program:

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

When you run this program, it will output:

Hello, World!

Python Syntax Basics

Python uses indentation (whitespace) to define code blocks, unlike many other languages that use braces:

# Example of indentation
if True:
    print("This is indented")
    print("So is this")
print("This is not indented")

Variables and Data Types

Python is a dynamically typed language, which means you don’t need to declare variable types:

# Integer
age = 25

# Float
temperature = 98.6

# String
name = "Alice"

# Boolean
is_student = True

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

# Dictionary
person = {"name": "Bob", "age": 30}

Basic Operations

Python supports standard arithmetic operations:

# Addition
sum = 5 + 3  # 8

# Subtraction
difference = 10 - 4  # 6

# Multiplication
product = 4 * 3  # 12

# Division
quotient = 8 / 2  # 4.0 (note: returns a float)

# Integer division
integer_division = 9 // 2  # 4 (discards remainder)

# Modulus (remainder)
remainder = 9 % 2  # 1

# Exponentiation
power = 2 ** 3  # 8

Practice Exercises

1. Write a program that calculates and prints the area of a rectangle with width 7 and height 5.
2. Create variables to store your name, age, and whether you’re a student. Print each variable on a new line.
3. Write a program that converts temperatures from Fahrenheit to Celsius using the formula: C = (F - 32) * 5/9