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<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Python Docs - Complete Tutorial</title>
<link rel="stylesheet" href="style.css">
</head>
<body>
<!-- NAVBAR -->
<nav id="navbar">
<div class="logo">Python Docs</div>
<div class="acc"><button>Sign in</button></div>
</nav>
<!-- SIDEBAR -->
<aside id="sidebar" class="sidebar">
<h1>PYTHON TUTORIAL</h1>
<ul class="topics">
<li><a href="#" onclick="showSection('intro'); return false;" id="link-intro" class="active">INTRO</a></li>
<li><a href="#" onclick="showSection('syntax'); return false;" id="link-syntax">SYNTAX AND OUTPUT</a></li>
<li><a href="#" onclick="showSection('dandv'); return false;" id="link-dandv">DATATYPES AND VARIABLES</a></li>
<li><a href="#" onclick="showSection('typecast'); return false;" id="link-typecast">TYPECASTING</a></li>
<li><a href="#" onclick="showSection('operator'); return false;" id="link-operator">OPERATORS</a></li>
<li><a href="#" onclick="showSection('cs'); return false;" id="link-cs">CONDITIONAL STATEMENTS</a></li>
<li><a href="#" onclick="showSection('loop'); return false;" id="link-loop">LOOPS</a></li>
<li><a href="#" onclick="showSection('jump'); return false;" id="link-jump">JUMPING STATEMENTS</a></li>
<li><a href="#" onclick="showSection('function'); return false;" id="link-function">FUNCTIONS</a></li>
<li><a href="#" onclick="showSection('list'); return false;" id="link-list">LISTS</a></li>
<li><a href="#" onclick="showSection('dst'); return false;" id="link-dst">DICTIONARIES,SETS,TUPLES</a></li>
<li><a href="#" onclick="showSection('strings'); return false;" id="link-strings">STRINGS</a></li>
<li><a href="#" onclick="showSection('recursion'); return false;" id="link-recursion">RECURSION</a></li>
</ul>
</aside>
<!-- MAIN CONTENT -->
<main id="content" class="content">
<div id="intro" class="page-section" style="display: block;">
<!-- Page heading -->
<h1>Introduction to Python</h1>
<!-- SECTION: History of Python -->
<section id="history">
<h2>History</h2>
<p>Python was created by Guido van Rossum in the late 1980s and first released in 1991. It was designed to emphasize code readability and developer productivity, using significant indentation to structure code. Over time Python grew a strong community and a rich standard library.</p>
<p>Major milestones include Python 2 (widely used for many years) and the release of Python 3 in 2008, which introduced improvements and some backward-incompatible changes. The community gradually migrated to Python 3 as the primary version. Today, Python 3 is the standard, with Python 2 officially deprecated since January 1, 2020.</p>
<p><strong>Key Milestones:</strong></p>
<ul>
<li><strong>1991:</strong> Python 0.9.0 released with classes, exception handling, functions, and core datatypes</li>
<li><strong>2000:</strong> Python 2.0 introduced list comprehensions and garbage collection</li>
<li><strong>2008:</strong> Python 3.0 released with major improvements (print function, better Unicode support, cleaner syntax)</li>
<li><strong>2020:</strong> Python 2 officially sunset; Python 3 is the only supported version</li>
</ul>
</section>
<!-- SECTION: Why Choose Python? -->
<section id="why-python">
<h2>Why Choose Python?</h2>
<p>Python has become one of the most popular programming languages worldwide for several compelling reasons:</p>
<ul>
<li><strong>Readable and Clean Syntax:</strong> Python's syntax is designed to be intuitive and readable, often resembling plain English. This makes it easier to learn and maintain code.</li>
<li><strong>Beginner-Friendly:</strong> Python is often the first language taught in schools and bootcamps because of its gentle learning curve.</li>
<li><strong>Versatile and Powerful:</strong> From web development to AI/ML, Python can handle diverse tasks across multiple domains.</li>
<li><strong>Rich Ecosystem:</strong> Thousands of libraries and frameworks (NumPy, pandas, Django, Flask, TensorFlow) extend Python's capabilities.</li>
<li><strong>Strong Community:</strong> Active community support, extensive documentation, and countless tutorials make problem-solving easier.</li>
<li><strong>Cross-Platform:</strong> Python runs on Windows, macOS, Linux, and more.</li>
<li><strong>High Demand:</strong> Python developers are in high demand across industries, making it a valuable career skill.</li>
</ul>
</section>
<!-- CODE TESTING BOX 1: Basic Python syntax example -->
<section id="try-basic">
<h3>Try It: Your First Python Program</h3>
<p>Below is a space to experiment with basic Python syntax. Try creating variables, printing output, and performing simple calculations.</p>
<!-- Empty code box for future JavaScript implementation -->
<div class="code-box" id="code-box-1">
<!-- JavaScript will enable code execution here later -->
</div>
</section>
<!-- SECTION: Key Features of Python -->
<section id="key-features">
<h2>Key Features</h2>
<h3>Interpreted Language</h3>
<p>Python code is executed line by line by the Python interpreter, making debugging easier and allowing for interactive programming in environments like IDLE or Jupyter notebooks.</p>
<h3>Dynamically Typed</h3>
<p>You don't need to declare variable types explicitly. Python infers types at runtime, making code more flexible but requiring careful testing.</p>
<h3>Object-Oriented</h3>
<p>Python supports object-oriented programming with classes and objects, enabling code reusability and modular design.</p>
<h3>Extensive Standard Library</h3>
<p>Python comes with a "batteries included" philosophy, providing modules for file I/O, regular expressions, web protocols, data serialization, and much more.</p>
<h3>Multi-Paradigm</h3>
<p>Python supports procedural, object-oriented, and functional programming paradigms, giving developers flexibility in how they structure their code.</p>
</section>
<!-- SECTION: Common Use Cases -->
<section id="use-cases">
<h2>Use Cases</h2>
<p>Python is a versatile language used across many domains because of its simple syntax and large ecosystem of libraries and frameworks. Common use cases include:</p>
<h3>Web Development</h3>
<p>Frameworks like <strong>Django</strong> and <strong>Flask</strong> make it easy to build robust, scalable web applications quickly. Django provides a full-featured MVC framework, while Flask offers a lightweight, flexible approach.</p>
<h3>Data Science and Analysis</h3>
<p>Python dominates the data science field with libraries like <strong>NumPy</strong>, <strong>pandas</strong>, and <strong>Matplotlib</strong>. These tools enable data manipulation, statistical analysis, and visualization.</p>
<h3>Machine Learning and AI</h3>
<p>Libraries such as <strong>scikit-learn</strong>, <strong>TensorFlow</strong>, and <strong>PyTorch</strong> make Python the go-to language for machine learning, deep learning, and artificial intelligence research and applications.</p>
<h3>Automation and Scripting</h3>
<p>Python excels at automating repetitive tasks like file management, web scraping (with <strong>BeautifulSoup</strong> and <strong>Scrapy</strong>), and system administration.</p>
<h3>Scientific Computing</h3>
<p>Python is widely used in scientific research and engineering with tools like <strong>SciPy</strong>, <strong>SymPy</strong>, and <strong>Biopython</strong> for complex calculations and simulations.</p>
<h3>Game Development</h3>
<p>While not the primary choice for AAA games, Python is used for game development with libraries like <strong>Pygame</strong> for 2D games and prototyping.</p>
<h3>Education</h3>
<p>Python's simplicity makes it ideal for teaching programming fundamentals in schools, universities, and online courses.</p>
<h3>DevOps and Cloud</h3>
<p>Python is used for infrastructure automation, configuration management (Ansible), and cloud service interactions (AWS SDK, Google Cloud SDK).</p>
</section>
<!-- CODE TESTING BOX 2: Exploring Python's versatility -->
<section id="try-versatility">
<h3>Try It: Explore Python's Versatility</h3>
<p>Experiment with different Python operations: string manipulation, list operations, or simple math calculations.</p>
<!-- Empty code box for future JavaScript implementation -->
<div class="code-box" id="code-box-2">
<!-- JavaScript will enable code execution here later -->
</div>
</section>
<!-- SECTION: Getting Started -->
<section id="getting-started">
<h2>Getting Started</h2>
<h3>Installing Python</h3>
<p>To start programming in Python, you need to install it on your computer:</p>
<ol>
<li>Visit the official Python website: <a href="https://www.python.org" target="_blank">python.org</a></li>
<li>Download the latest version of Python 3</li>
<li>Run the installer (make sure to check "Add Python to PATH" on Windows)</li>
<li>Verify installation by opening a terminal/command prompt and typing: <code>python --version</code></li>
</ol>
<h3>Your First Program</h3>
<p>The traditional first program in any language is "Hello, World!". In Python, it's remarkably simple:</p>
<div class="callout">
<code>print("Hello, World!")</code>
</div>
<p>That's it! Just one line creates output. This simplicity is what makes Python so appealing to beginners.</p>
<h3>Development Environments</h3>
<p>You can write Python code in various environments:</p>
<ul>
<li><strong>IDLE:</strong> Comes bundled with Python, simple and lightweight</li>
<li><strong>VS Code:</strong> Popular, feature-rich editor with excellent Python support</li>
<li><strong>PyCharm:</strong> Professional IDE specifically designed for Python</li>
<li><strong>Jupyter Notebook:</strong> Interactive environment perfect for data science and learning</li>
<li><strong>Sublime Text / Atom:</strong> Lightweight text editors with Python plugins</li>
</ul>
</section>
<!-- CODE TESTING BOX 3: Hello World variations -->
<section id="try-hello">
<h3>Try It: Create Your Own Hello World</h3>
<p>Practice writing your first Python program. Try variations of Hello World with different messages.</p>
<!-- Empty code box for future JavaScript implementation -->
<div class="code-box" id="code-box-3">
<!-- JavaScript will enable code execution here later -->
</div>
</section>
<!-- SECTION: What's Next? -->
<section id="whats-next">
<h2>What's Next?</h2>
<p>Now that you understand what Python is and why it's valuable, you're ready to dive into the fundamentals:</p>
<ul>
<li><strong>Syntax and Output:</strong> Learn how Python code is structured and how to display information</li>
<li><strong>Datatypes and Variables:</strong> Understand how to store and manage data</li>
<li><strong>Control Flow:</strong> Make decisions and repeat actions in your programs</li>
<li><strong>Functions:</strong> Organize code into reusable blocks</li>
<li><strong>Data Structures:</strong> Work with collections of data efficiently</li>
</ul>
<p>Use the sidebar to navigate to the next topic and continue your Python learning journey!</p>
</section>
</div>
<div id="syntax" class="page-section" style="display: none;">
<!-- Page heading -->
<h1>Syntax and Output</h1>
<!-- SECTION: Overview -->
<section id="overview">
<h2>Overview</h2>
<p>Python code is written using a clean, easy-to-read syntax that emphasizes readability and simplicity. Unlike many other programming languages, Python uses <strong>indentation (whitespace)</strong> to define code blocks instead of braces or keywords. Output is typically produced with the built-in <code>print()</code> function.</p>
<p>This design philosophy makes Python code look almost like pseudocode, which reduces the learning curve and makes programs easier to understand and maintain.</p>
</section>
<!-- SECTION: Basic Syntax Rules -->
<section id="syntax-rules">
<h2>Basic Syntax Rules</h2>
<h3>1. Statements and Line Endings</h3>
<p>In Python, each statement typically appears on its own line. Unlike languages like C or Java, you don't need to end statements with a semicolon (though you can use semicolons to separate multiple statements on one line).</p>
<div class="callout">
<code>name = "Alice" # This is a complete statement</code><br>
<code>age = 25 # Each variable assignment is on its own line</code>
</div>
<h3>2. Line Continuation</h3>
<p>Long statements can be split across multiple lines using a backslash (<code>\</code>) or by placing expressions inside parentheses, brackets, or braces.</p>
<div class="callout">
<code>total = 1 + 2 + 3 + \</code><br>
<code> 4 + 5 + 6</code><br><br>
<code># Or using parentheses:</code><br>
<code>total = (1 + 2 + 3 +</code><br>
<code> 4 + 5 + 6)</code>
</div>
<h3>3. Case Sensitivity</h3>
<p>Python is case-sensitive, meaning <code>Variable</code>, <code>variable</code>, and <code>VARIABLE</code> are three different identifiers.</p>
</section>
<!-- CODE TESTING BOX 1: Basic syntax practice -->
<section id="try-basic-syntax">
<h3>Try It: Practice Basic Syntax</h3>
<p>Write simple Python statements and see how line endings work. Try creating variables and printing them.</p>
<!-- Empty code box for future JavaScript implementation -->
<div class="code-box" id="code-box-1">
<!-- JavaScript will enable code execution here later -->
</div>
</section>
<!-- SECTION: Indentation -->
<section id="indentation">
<h2>Indentation</h2>
<p><strong>Indentation is critical in Python</strong> – it's not just for readability, it's part of the syntax. Indentation defines code blocks and scope.</p>
<h3>Why Indentation Matters</h3>
<ul>
<li>Indentation replaces braces <code>{ }</code> used in other languages</li>
<li>All statements within a block must be indented by the same amount</li>
<li>The standard is <strong>4 spaces</strong> per indentation level (not tabs)</li>
<li>Inconsistent indentation will cause an <code>IndentationError</code></li>
</ul>
<h3>Example:</h3>
<div class="callout">
<code>if True:</code><br>
<code> print("This is indented") # 4 spaces</code><br>
<code> print("Still in the block") # Same indentation</code><br>
<code>print("Back to no indentation") # Outside the block</code>
</div>
<p><strong>Important:</strong> Never mix tabs and spaces for indentation. Most modern code editors automatically convert tabs to spaces.</p>
</section>
<!-- CODE TESTING BOX 2: Indentation practice -->
<section id="try-indentation">
<h3>Try It: Practice Indentation</h3>
<p>Experiment with indentation by creating if statements or other block structures. See what happens with incorrect indentation.</p>
<!-- Empty code box for future JavaScript implementation -->
<div class="code-box" id="code-box-2">
<!-- JavaScript will enable code execution here later -->
</div>
</section>
<!-- SECTION: Comments -->
<section id="comments">
<h2>Comments</h2>
<p>Comments are notes in your code that Python ignores during execution. They're essential for documenting your code and making it understandable.</p>
<h3>Single-Line Comments</h3>
<p>Use the hash symbol <code>#</code> to create a single-line comment. Everything after <code>#</code> on that line is ignored.</p>
<div class="callout">
<code># This is a comment</code><br>
<code>x = 5 # This is also a comment (inline)</code>
</div>
<h3>Multi-Line Comments</h3>
<p>Python doesn't have a specific multi-line comment syntax, but you can use multiple <code>#</code> symbols or triple quotes (which create multi-line strings that can serve as comments).</p>
<div class="callout">
<code>"""</code><br>
<code>This is a multi-line comment.</code><br>
<code>It can span several lines.</code><br>
<code>Useful for documentation.</code><br>
<code>"""</code>
</div>
<h3>Best Practices for Comments</h3>
<ul>
<li>Write comments that explain <em>why</em>, not <em>what</em> (the code itself shows what)</li>
<li>Keep comments up-to-date when code changes</li>
<li>Use comments to explain complex logic or algorithms</li>
<li>Avoid obvious comments like <code># increment x</code> for <code>x = x + 1</code></li>
</ul>
</section>
<!-- SECTION: The Print Function -->
<section id="print-function">
<h2>The Print Function</h2>
<p>The <code>print()</code> function is your primary tool for displaying output in Python. It sends text or data to the console/terminal.</p>
<h3>Basic Usage</h3>
<div class="callout">
<code>print("Hello, World!")</code><br>
<code>print(42)</code><br>
<code>print(3.14159)</code>
</div>
<h3>Printing Multiple Items</h3>
<p>You can print multiple items separated by commas. Python automatically adds a space between them.</p>
<div class="callout">
<code>print("Age:", 25)</code><br>
<code># Output: Age: 25</code>
</div>
<h3>Customizing Separators</h3>
<p>Use the <code>sep</code> parameter to change how items are separated:</p>
<div class="callout">
<code>print("apple", "banana", "cherry", sep=", ")</code><br>
<code># Output: apple, banana, cherry</code>
</div>
<h3>Controlling Line Endings</h3>
<p>By default, <code>print()</code> adds a newline at the end. Use the <code>end</code> parameter to change this:</p>
<div class="callout">
<code>print("Hello", end=" ")</code><br>
<code>print("World")</code><br>
<code># Output: Hello World</code>
</div>
<h3>String Formatting in Print</h3>
<p>Modern Python offers several ways to format strings for output:</p>
<h4>1. f-strings (Python 3.6+) - Recommended</h4>
<div class="callout">
<code>name = "Alice"</code><br>
<code>age = 30</code><br>
<code>print(f"My name is {name} and I am {age} years old")</code>
</div>
<h4>2. .format() Method</h4>
<div class="callout">
<code>print("My name is {} and I am {} years old".format(name, age))</code>
</div>
<h4>3. % Operator (Older Style)</h4>
<div class="callout">
<code>print("My name is %s and I am %d years old" % (name, age))</code>
</div>
</section>
<!-- CODE TESTING BOX 3: Print function practice -->
<section id="try-print">
<h3>Try It: Master the Print Function</h3>
<p>Practice using print() with different parameters. Try sep, end, and various formatting methods.</p>
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<div class="code-box" id="code-box-3">
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</div>
</section>
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<section id="input-function">
<h2>Receiving Input</h2>
<p>The <code>input()</code> function allows your program to receive text input from the user. It displays a prompt and waits for the user to type something and press Enter.</p>
<h3>Basic Usage</h3>
<div class="callout">
<code>name = input("Enter your name: ")</code><br>
<code>print(f"Hello, {name}!")</code>
</div>
<p><strong>Important:</strong> <code>input()</code> always returns a <strong>string</strong>. If you need a number, you must convert it:</p>
<div class="callout">
<code>age = int(input("Enter your age: ")) # Convert to integer</code><br>
<code>height = float(input("Enter height: ")) # Convert to float</code>
</div>
</section>
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<section id="try-input-output">
<h3>Try It: Combine Input and Output</h3>
<p>Create a program that asks for user input and displays formatted output. Try different data types and formatting.</p>
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</section>
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<section id="common-errors">
<h2>Common Syntax Errors to Avoid</h2>
<ul>
<li><strong>IndentationError:</strong> Mixing tabs and spaces, or inconsistent indentation levels</li>
<li><strong>SyntaxError:</strong> Missing colons after if, for, while, def, or class statements</li>
<li><strong>NameError:</strong> Using variables before defining them or misspelling variable names</li>
<li><strong>TypeError:</strong> Trying to concatenate strings with numbers without conversion</li>
</ul>
<p>Always read error messages carefully – Python error messages are usually helpful in identifying what went wrong and where.</p>
</section>
<!-- SECTION: Quick Reference -->
<section id="quick-reference">
<h2>Quick Reference</h2>
<div class="callout">
<strong>Key Takeaways:</strong>
<ul>
<li>Statements end with a newline (no semicolons needed)</li>
<li>Use <strong>4 spaces</strong> for each indentation level</li>
<li>Comments start with <code>#</code></li>
<li><code>print()</code> displays output</li>
<li><code>input()</code> receives user input (always returns a string)</li>
<li>Python is case-sensitive</li>
<li>Indentation defines code blocks</li>
</ul>
</div>
</section>
<!-- SECTION: Next Steps -->
<section id="next-steps">
<h2>Next Steps</h2>
<p>Now that you understand Python's syntax and how to produce output, you're ready to learn about <strong>datatypes and variables</strong> – the building blocks for storing and manipulating data in your programs.</p>
</section>
</div>
<div id="dandv" class="page-section" style="display: none;">
<!-- Page heading -->
<h1>Datatypes & Variables</h1>
<!-- SECTION: Overview -->
<section id="overview">
<h2>Overview</h2>
<p>Python provides several built-in datatypes for storing different kinds of information: numbers, text, collections, and more. <strong>Variables</strong> are containers that store these values, and Python is <strong>dynamically typed</strong>, meaning you don't need to declare a variable's type explicitly – Python infers it automatically.</p>
<p>Understanding datatypes is fundamental to programming because different types of data support different operations and behave differently in your programs.</p>
</section>
<!-- SECTION: Variables -->
<section id="variables">
<h2>Variables</h2>
<h3>What is a Variable?</h3>
<p>A variable is a named location in memory that stores a value. Think of it as a labeled box where you can put data and retrieve it later by using the label (variable name).</p>
<h3>Creating Variables</h3>
<p>In Python, you create a variable simply by assigning a value to it using the equals sign <code>=</code>:</p>
<div class="callout">
<code>name = "Alice" # String variable</code><br>
<code>age = 25 # Integer variable</code><br>
<code>height = 5.6 # Float variable</code><br>
<code>is_student = True # Boolean variable</code>
</div>
<h3>Variable Naming Rules</h3>
<p>Follow these rules when naming variables:</p>
<ul>
<li>Must start with a letter (a-z, A-Z) or underscore (_)</li>
<li>Can contain letters, numbers, and underscores</li>
<li>Cannot start with a number</li>
<li>Cannot use Python keywords (like <code>if</code>, <code>for</code>, <code>while</code>, etc.)</li>
<li>Case-sensitive: <code>age</code> and <code>Age</code> are different variables</li>
</ul>
<h3>Naming Conventions (Best Practices)</h3>
<ul>
<li>Use <strong>snake_case</strong> for variable names: <code>user_name</code>, <code>total_amount</code></li>
<li>Use descriptive names: <code>student_count</code> instead of <code>sc</code></li>
<li>Constants should be in UPPERCASE: <code>MAX_SIZE = 100</code></li>
<li>Avoid single-letter names except for counters (<code>i</code>, <code>j</code>) or mathematical formulas</li>
</ul>
<h3>Multiple Assignment</h3>
<p>Python allows you to assign multiple variables in one line:</p>
<div class="callout">
<code>x, y, z = 10, 20, 30</code><br>
<code>a = b = c = 0 # All assigned the same value</code>
</div>
</section>
<!-- CODE TESTING BOX 1: Variable practice -->
<section id="try-variables">
<h3>Try It: Create and Use Variables</h3>
<p>Practice creating variables with different names and values. Try multiple assignment and see how variables work.</p>
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</section>
<!-- SECTION: Numeric Types -->
<section id="numeric-types">
<h2>Numeric Datatypes</h2>
<h3>1. Integer (int)</h3>
<p>Whole numbers without a decimal point. Can be positive, negative, or zero.</p>
<div class="callout">
<code>count = 42</code><br>
<code>temperature = -15</code><br>
<code>zero = 0</code>
</div>
<p><strong>Note:</strong> Python integers have unlimited precision – they can be as large as your memory allows!</p>
<h3>2. Float (float)</h3>
<p>Numbers with decimal points. Used for measurements, calculations requiring precision, etc.</p>
<div class="callout">
<code>pi = 3.14159</code><br>
<code>price = 19.99</code><br>
<code>negative_float = -7.5</code>
</div>
<p><strong>Scientific Notation:</strong> You can use <code>e</code> for powers of 10:</p>
<div class="callout">
<code>large_number = 1.5e6 # 1,500,000</code><br>
<code>small_number = 2.5e-3 # 0.0025</code>
</div>
<h3>3. Complex (complex)</h3>
<p>Numbers with real and imaginary parts, using <code>j</code> to denote the imaginary component.</p>
<div class="callout">
<code>z = 3 + 4j</code><br>
<code>print(z.real) # 3.0</code><br>
<code>print(z.imag) # 4.0</code>
</div>
<h3>Checking Type</h3>
<p>Use the <code>type()</code> function to check a variable's datatype:</p>
<div class="callout">
<code>x = 10</code><br>
<code>print(type(x)) # <class 'int'></code>
</div>
</section>
<!-- CODE TESTING BOX 2: Numeric types practice -->
<section id="try-numeric">
<h3>Try It: Work with Numbers</h3>
<p>Create variables of different numeric types. Use type() to check their types and perform basic arithmetic.</p>
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</section>
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<section id="string-type">
<h2>String (str)</h2>
<p>Strings represent text data. They can be enclosed in single quotes, double quotes, or triple quotes for multi-line strings.</p>
<h3>Creating Strings</h3>
<div class="callout">
<code>name = "Alice" # Double quotes</code><br>
<code>greeting = 'Hello' # Single quotes</code><br>
<code>message = """This is</code><br>
<code>a multi-line</code><br>
<code>string""" # Triple quotes</code>
</div>
<h3>String Operations</h3>
<ul>
<li><strong>Concatenation:</strong> <code>"Hello" + " " + "World"</code> → <code>"Hello World"</code></li>
<li><strong>Repetition:</strong> <code>"Ha" * 3</code> → <code>"HaHaHa"</code></li>
<li><strong>Length:</strong> <code>len("Python")</code> → <code>6</code></li>
<li><strong>Indexing:</strong> <code>"Python"[0]</code> → <code>"P"</code></li>
</ul>
<p>Strings are <strong>immutable</strong> – once created, they cannot be changed. Any operation that appears to modify a string actually creates a new string.</p>
</section>
<!-- SECTION: Boolean Type -->
<section id="boolean-type">
<h2>Boolean (bool)</h2>
<p>Booleans represent truth values: <code>True</code> or <code>False</code>. They're essential for conditional logic and decision-making in programs.</p>
<div class="callout">
<code>is_active = True</code><br>
<code>has_permission = False</code><br><br>
<code># From comparisons:</code><br>
<code>result = (5 > 3) # True</code><br>
<code>equal = (10 == 20) # False</code>
</div>
<h3>Truthy and Falsy Values</h3>
<p>In Python, certain values are considered "falsy" (evaluate to False in boolean context):</p>
<ul>
<li><code>None</code></li>
<li><code>False</code></li>
<li>Zero: <code>0</code>, <code>0.0</code></li>
<li>Empty sequences: <code>""</code>, <code>[]</code>, <code>()</code>, <code>{}</code></li>
</ul>
<p>All other values are "truthy" (evaluate to True).</p>
</section>
<!-- SECTION: Collection Types -->
<section id="collection-types">
<h2>Collection Datatypes</h2>
<h3>1. List (list)</h3>
<p>Ordered, mutable collection of items. Items can be of different types.</p>
<div class="callout">
<code>fruits = ["apple", "banana", "cherry"]</code><br>
<code>mixed = [1, "text", 3.14, True]</code><br>
<code>empty_list = []</code>
</div>
<p>Lists are versatile and the most commonly used collection type in Python.</p>
<h3>2. Tuple (tuple)</h3>
<p>Ordered, <strong>immutable</strong> collection. Once created, cannot be modified.</p>
<div class="callout">
<code>coordinates = (10, 20)</code><br>
<code>rgb_color = (255, 128, 0)</code><br>
<code>single_item = (42,) # Note the comma</code>
</div>
<p>Use tuples for data that shouldn't change, like coordinates or configuration values.</p>
<h3>3. Dictionary (dict)</h3>
<p>Unordered collection of key-value pairs. Keys must be unique and immutable.</p>
<div class="callout">
<code>person = {</code><br>
<code> "name": "Alice",</code><br>
<code> "age": 30,</code><br>
<code> "city": "Seattle"</code><br>
<code>}</code><br>
<code>print(person["name"]) # Access by key</code>
</div>
<h3>4. Set (set)</h3>
<p>Unordered collection of <strong>unique</strong> items. Automatically removes duplicates.</p>
<div class="callout">
<code>unique_numbers = {1, 2, 3, 4, 5}</code><br>
<code>letters = {'a', 'b', 'c'}</code><br>
<code># Duplicates are removed:</code><br>
<code>numbers = {1, 2, 2, 3, 3, 3} # Result: {1, 2, 3}</code>
</div>
</section>
<!-- CODE TESTING BOX 3: Collection types practice -->
<section id="try-collections">
<h3>Try It: Explore Collections</h3>
<p>Create lists, tuples, dictionaries, and sets. Access their elements and see how they behave differently.</p>
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</section>
<!-- SECTION: None Type -->
<section id="none-type">
<h2>None Type</h2>
<p><code>None</code> is Python's null value. It represents the absence of a value or a null reference.</p>
<div class="callout">
<code>result = None</code><br>
<code>if result is None:</code><br>
<code> print("No value assigned")</code>
</div>
<p>Use <code>is None</code> or <code>is not None</code> to check for None values, not <code>== None</code>.</p>
</section>
<!-- SECTION: Type Conversion -->
<section id="type-conversion-intro">
<h2>Quick Type Conversion</h2>
<p>You can convert between types using built-in functions:</p>
<div class="callout">
<code># To integer:</code><br>
<code>int("42") # "42" → 42</code><br>
<code>int(3.14) # 3.14 → 3 (truncates)</code><br><br>
<code># To float:</code><br>
<code>float("3.14") # "3.14" → 3.14</code><br>
<code>float(42) # 42 → 42.0</code><br><br>
<code># To string:</code><br>
<code>str(42) # 42 → "42"</code><br>
<code>str(3.14) # 3.14 → "3.14"</code><br><br>
<code># To boolean:</code><br>
<code>bool(0) # 0 → False</code><br>
<code>bool(42) # 42 → True</code>
</div>
<p>See the <a href="typecast.html">Typecasting</a> section for more detailed information on type conversion.</p>
</section>
<!-- CODE TESTING BOX 4: Type conversion practice -->
<section id="try-conversion">
<h3>Try It: Convert Between Types</h3>
<p>Practice converting values between different datatypes. Use type() to verify the conversions.</p>
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</section>
<!-- SECTION: Quick Reference -->
<section id="quick-reference">
<h2>Quick Reference</h2>
<div class="callout">
<strong>Summary of Common Datatypes:</strong>
<ul>
<li><strong>int</strong> — Integers (whole numbers): <code>42</code>, <code>-3</code></li>
<li><strong>float</strong> — Floating point numbers: <code>3.14</code>, <code>-0.5</code></li>
<li><strong>str</strong> — Strings (text): <code>"Hello"</code>, <code>'Python'</code></li>
<li><strong>bool</strong> — Booleans: <code>True</code>, <code>False</code></li>
<li><strong>list</strong> — Ordered, mutable: <code>[1, 2, 3]</code></li>
<li><strong>tuple</strong> — Ordered, immutable: <code>(1, 2, 3)</code></li>
<li><strong>dict</strong> — Key-value pairs: <code>{"key": "value"}</code></li>
<li><strong>set</strong> — Unique items: <code>{1, 2, 3}</code></li>
<li><strong>NoneType</strong> — Null value: <code>None</code></li>
</ul>
</div>
</section>
<!-- SECTION: Next Steps -->
<section id="next-steps">
<h2>Next Steps</h2>
<p>Now that you understand Python's datatypes and how to store data in variables, you're ready to learn about <strong>typecasting</strong> – explicitly converting data from one type to another for more control in your programs.</p>
</section>
</div>
<div id="typecast" class="page-section" style="display: none;">
<!-- Page heading -->
<h1>Typecasting</h1>
<!-- SECTION: Overview -->
<section id="overview">
<h2>Overview</h2>
<p>Typecasting (also called type conversion) is the process of changing a value from one datatype to another. Python performs some conversions automatically (<strong>implicit conversion</strong>), but often you'll need to convert explicitly (<strong>explicit conversion</strong>) using built-in functions like <code>int()</code>, <code>float()</code>, <code>str()</code>, and <code>list()</code>.</p>
<p>Understanding typecasting is crucial because different operations require specific datatypes, and user input always comes as strings and often needs conversion.</p>
</section>
<!-- SECTION: Implicit vs Explicit -->
<section id="implicit-explicit">
<h2>Implicit vs Explicit Conversion</h2>
<h3>Implicit Conversion (Automatic)</h3>
<p>Python automatically converts smaller datatypes to larger ones to prevent data loss. This happens without your intervention.</p>
<div class="callout">
<code>x = 10 # int</code><br>
<code>y = 3.5 # float</code><br>
<code>result = x + y # Python converts x to float: 13.5</code><br>
<code>print(type(result)) # <class 'float'></code>
</div>
<p>In this example, Python automatically converts the integer to a float before adding because float is a "wider" type that can represent both integers and decimals.</p>
<h3>Explicit Conversion (Manual)</h3>
<p>You explicitly convert values using conversion functions. This gives you full control over how data is converted.</p>
<div class="callout">
<code>text = "42"</code><br>
<code>number = int(text) # Explicitly convert string to int</code><br>
<code>print(number + 8) # Now we can do math: 50</code>
</div>
</section>
<!-- CODE TESTING BOX 1: Implicit vs explicit practice -->
<section id="try-conversions">
<h3>Try It: Explore Implicit and Explicit Conversion</h3>
<p>Experiment with automatic and manual type conversions. See what happens when you mix different types.</p>
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<div class="code-box" id="code-box-1">
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</section>
<!-- SECTION: Common Conversion Functions -->
<section id="conversion-functions">
<h2>Common Conversion Functions</h2>
<h3>1. Converting to Integer: int()</h3>
<p>Converts a value to an integer (whole number). Truncates decimal portions.</p>
<div class="callout">
<code># From float (truncates):</code><br>
<code>int(3.99) # → 3 (not rounded!)</code><br>
<code>int(-2.7) # → -2</code><br><br>
<code># From string:</code><br>
<code>int("42") # → 42</code><br>
<code>int(" 100 ") # → 100 (ignores whitespace)</code><br><br>
<code># From boolean:</code><br>
<code>int(True) # → 1</code><br>
<code>int(False) # → 0</code>
</div>
<p><strong>Important:</strong> <code>int("3.14")</code> will cause an error! You must convert to float first: <code>int(float("3.14"))</code></p>
<h3>2. Converting to Float: float()</h3>
<p>Converts a value to a floating-point number (with decimal).</p>
<div class="callout">
<code># From integer:</code><br>
<code>float(42) # → 42.0</code><br><br>
<code># From string:</code><br>
<code>float("3.14") # → 3.14</code><br>
<code>float("100") # → 100.0</code><br><br>
<code># From boolean:</code><br>
<code>float(True) # → 1.0</code><br>
<code>float(False) # → 0.0</code>
</div>
<h3>3. Converting to String: str()</h3>
<p>Converts any value to a string representation. This almost always works!</p>
<div class="callout">
<code>str(42) # → "42"</code><br>
<code>str(3.14) # → "3.14"</code><br>
<code>str(True) # → "True"</code><br>
<code>str([1, 2, 3]) # → "[1, 2, 3]"</code><br>
<code>str(None) # → "None"</code>
</div>
<p><strong>Use Case:</strong> Combining numbers with text in print statements:</p>
<div class="callout">
<code>age = 25</code><br>
<code>message = "I am " + str(age) + " years old"</code><br>
<code># Or use f-strings (better): f"I am {age} years old"</code>
</div>
<h3>4. Converting to Boolean: bool()</h3>
<p>Converts any value to a boolean (True or False).</p>
<div class="callout">
<code># Falsy values → False:</code><br>
<code>bool(0) # → False</code><br>
<code>bool("") # → False (empty string)</code><br>
<code>bool([]) # → False (empty list)</code><br>
<code>bool(None) # → False</code><br><br>
<code># Everything else → True:</code><br>
<code>bool(42) # → True</code><br>
<code>bool("Hello") # → True</code><br>
<code>bool([1, 2, 3]) # → True</code>
</div>
<h3>5. Converting to List, Tuple, Set</h3>
<p>Convert between collection types:</p>
<div class="callout">
<code># String to list:</code><br>
<code>list("abc") # → ['a', 'b', 'c']</code><br><br>
<code># Tuple to list:</code><br>
<code>list((1, 2, 3)) # → [1, 2, 3]</code><br><br>
<code># List to tuple:</code><br>
<code>tuple([1, 2, 3]) # → (1, 2, 3)</code><br><br>
<code># List to set (removes duplicates):</code><br>
<code>set([1, 2, 2, 3]) # → {1, 2, 3}</code>
</div>
</section>
<!-- CODE TESTING BOX 2: Conversion functions practice -->
<section id="try-functions">
<h3>Try It: Practice Conversion Functions</h3>
<p>Use int(), float(), str(), bool(), and collection conversion functions. Try edge cases!</p>
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<div class="code-box" id="code-box-2">
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</section>
<!-- SECTION: Handling Errors -->
<section id="error-handling">
<h2>Handling Conversion Errors</h2>
<h3>Common Errors</h3>
<p>Not all conversions are possible. Here are common scenarios that cause errors:</p>
<ul>
<li><strong>ValueError:</strong> Trying to convert invalid string to number</li>
<li><strong>TypeError:</strong> Incompatible types in operation</li>
</ul>
<h3>Examples of Invalid Conversions:</h3>
<div class="callout">
<code># ValueError - invalid literal:</code><br>
<code>int("hello") # ERROR: can't convert text to int</code><br>
<code>float("12.5.3") # ERROR: invalid format</code><br><br>
<code># TypeError - incompatible operation:</code><br>
<code>"age: " + 25 # ERROR: can't concatenate str and int</code><br>
<code># Fix: "age: " + str(25)</code>
</div>
<h3>Safe Conversion with Try-Except</h3>
<p>Use try-except blocks to handle potential conversion errors gracefully:</p>
<div class="callout">
<code>user_input = "abc"</code><br><br>
<code>try:</code><br>
<code> number = int(user_input)</code><br>
<code> print(f"Converted: {number}")</code><br>
<code>except ValueError:</code><br>
<code> print("Invalid number format!")</code>
</div>
<h3>Validation Before Conversion</h3>
<p>Check if conversion is possible using string methods:</p>
<div class="callout">
<code>text = "123"</code><br>
<code>if text.isdigit():</code><br>
<code> number = int(text)</code><br>
<code> print("Valid integer:", number)</code><br>
<code>else:</code><br>
<code> print("Not a valid integer")</code>
</div>
</section>
<!-- CODE TESTING BOX 3: Error handling practice -->
<section id="try-errors">
<h3>Try It: Handle Conversion Errors</h3>
<p>Experiment with invalid conversions and use try-except to handle them safely.</p>
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<h2>Practical Examples</h2>
<h3>Example 1: User Input Processing</h3>
<p>Convert string input to numbers for calculations:</p>
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<code># All input() returns strings!</code><br>
<code>age_str = input("Enter your age: ")</code><br>
<code>age = int(age_str) # Convert to int</code><br>
<code>years_to_100 = 100 - age</code><br>
<code>print(f"You have {years_to_100} years until 100!")</code>
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<h3>Example 2: Data Cleaning</h3>
<p>Remove duplicates by converting list to set and back:</p>
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<code>numbers = [1, 2, 2, 3, 4, 4, 5]</code><br>
<code>unique = list(set(numbers)) # [1, 2, 3, 4, 5]</code>
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<h3>Example 3: Temperature Conversion</h3>
<p>Convert between Celsius and Fahrenheit:</p>
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<code>celsius_str = "25"</code><br>
<code>celsius = float(celsius_str)</code><br>
<code>fahrenheit = (celsius * 9/5) + 32</code><br>
<code>print(f"{celsius}°C = {fahrenheit}°F")</code>
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<h3>Example 4: String to List for Processing</h3>
<p>Convert comma-separated string to list:</p>
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<code>fruits_str = "apple,banana,cherry"</code><br>
<code>fruits_list = fruits_str.split(",") # ['apple', 'banana', 'cherry']</code>
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<h3>Try It: Real-World Typecasting</h3>
<p>Create programs that use typecasting for practical tasks like input processing or data conversion.</p>
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<h2>Quick Reference</h2>