Python Keywords Quiz

Introduction to Python

• Python is an open-source, high-level, dynamically typed, interpreted, object-oriented programming language
• Created by Guido van Rossum in 1991
• Known for its simplicity and readability
• Its syntax allows programmers to express concepts in fewer lines of code
• Enables quick development and system integration

Versions of Python

• Python 1.x (1991): Introduced basic features like exception handling, functions and core data types (lists, dictionaries, etc.)
• Python 2.x (2000): Introduced list comprehensions, garbage collection, yield statement, and more libraries/modules. Unicode support was introduced with a 'u' prefix. Integer division yielded integer values.
• Python 3.x (2008): Changed print statement to print() function. Integer division now yields float values. All strings are Unicode by default. Iterators instead of lists from range and other functions. Enhanced standard libraries. Improved syntax for better readability and consistency.

Key Differences Between Python 2.x and 3.x

• Print Statement: Python 2 used "print "Hello, World!" ", Python 3 uses print("Hello, World!")"
• Integer Division: Python 2: 5 / 2 = 2, Python 3: 5 / 2 = 2.5
• Unicode Handling: Python 2: Strings are ASCII, Unicode needed "u" prefix, Python 3: Strings are Unicode
• Iterators: Python 2: range(5) returns a list, Python 3: range(5) returns a range object (iterator)
• Other improvements: Python 3 included several library and syntax changes for better performance and efficiency.

Features of Python

• Readability and Writeability: Python's clear and concise syntax is great for beginners and experienced developers
• Interpreted Language: Python executes code line by line, making debugging easier
• Dynamically Typed: Python doesn't require explicit variable type declarations. It's flexible but needs careful variable management
• Extensive Standard Library: Python's vast library supports many common programming tasks.
• Cross-Platform Compatibility: Python programs run on multiple operating systems without modifications.

Common Uses of Python

• Web Development: Frameworks like Django, Flask, and Pyramid support efficient web application development.
• Data Science and Machine Learning: Libraries like NumPy, Pandas, and Scikit-learn are popular for data analysis and machine learning tasks.
• Automation and Scripting: Python is frequently used for writing scripts to automate repetitive tasks
• Game Development: Libraries like Pygame provide tools for game creation
• Network Programming: Python provides strong support to develop complex network applications.

How to Install Python

• Visit the Python website's download section.
• Choose your desired Python version (e.g., Python 3.x).
• Download the installer (.exe, .pkg, or .tar.gz).
• Execute the installer according to your operating system.
• Confirm installation by running a simple Python script in the terminal, like "python --version".

Installing Python on Different OS

• Windows: Double-click the downloaded .exe file to begin the installation. Select 'Add to PATH' during installation and follow instructions.
• macOS: Use the Terminal app and enter the command brew install python3.
• Linux: Usually, Python is already installed. Verify in the terminal using python --version.

Python Interpreter

• The Python interpreter, also known as the Python shell, allows direct interactions with the Python interpreter for executing code, commands, and programs
• It uses a read-eval-print loop (REPL) to accept input, evaluate it, and print the output, looping for further input.

Python Interpreter: Steps Performed

• Parsing: Reads source code and checks for syntax errors. Turns it into tokens and creates an Abstract Syntax Tree (AST).
• Compilation: Converts the AST into bytecode. Bytecode is an intermediary, platform-independent representation of the original source code.
• Execution: The Python Virtual Machine (PVM) interprets the bytecode and converts it into machine code to execute.

Intermediate Files Generated

• Bytecode files, often .pyc files, are stored in the .pycache_ directory. These files are utilized for future quicker executions by not requiring recompilation.

Key Features of Abstract Syntax Tree (AST)

• Abstraction: The AST hides the formatting and other details of the code structure.
• Hierarchy: The AST captures the hierarchical structure of the code, improving analysis and manipulation.
• Nodes: Each node in the AST corresponds to a code construct (expression, statement, or code block) with associated sub-constructs as children.

Indentation

• Python uses indentation (whitespace) to structure code blocks, instead of brackets like in Java or C
• Consistent indentation is important for correct code execution

Python Keywords

• Keywords are reserved words in Python that have predefined meanings and usage; they are part of the Python language syntax.
• Python does not allow using keywords as names for variables or functions.

Python Data Types

• Numeric: Integer (int), Float (float), Complex (complex) for numerical values.
• Sequence Types: String (str), List (list), Tuple (tuple)—store sequences of values. Strings are a type of sequence holding unicode characters.
• Boolean: True or False
• Set: A collection of unordered, unique items (set).
• Dictionary: A collection of key-value pairs (dict).

Input/Output Statements

• Input: The input() function collects user input, returning it as a string. Input (prompt) - a string to guide user
• Output: The print() function displays output on the screen. Print (objects, sep=' ', end='\n',...)- for printing. objects: anything to print, sep: a separator (default space), end: a character to append to end of line (default newline ), file: the text output stream, flush: force output immidiately

Arithmetic Operators

• Used for mathematical calculations.
• Examples: +, -, *, /, // (floor division), %, ** (exponent)

Assignment Operators

• Used to assign values to variables.
• Examples: =, +=, -=, *=, /=, //=

Comparison Operators

• Used in conditional statements to compare values.
• Examples: ==, !=, <, >, <=, >=

Logical Operators

• Used to combine conditions.
• Examples: and, or, not.

Membership Operators

• Used to test for membership in a sequence (string, list, tuple).
• Examples: in, not in.

Identity Operators

• Used to check if two variables refer to the same object in memory.
• Examples: is, is not.

Slice Function

• Used to extract a portion of a sequence (like a list or string).
• Syntax: slice(start, stop, step). Defaults to step = 1, start = 0, stop = end.

Bitwise Operators

• Used to perform bit-by-bit operations on integers.
• Examples: &, |, ^, ~, << (left shift), >> (right shift)

Conditional Statements (if, elif, else)

• Control the flow of a program based on conditions.
• if: Execute a block if a condition is true.
• elif: Execute a block if the previous if or elif conditions are false, and this condition is true.
• else: Execute a block if all previous conditions are false.

Loops (for, while)

• Repeat a block of code multiple times
• for: Iterate through each item within a sequence.
• while: Repeat a block of code as long as a condition is true

Loop Control Statements

• Break: Immediately exits a loop.
• Continue: Skips the current iteration of a loop
• pass: A null operation—does nothing. Used as a placeholder.

File Handling

• open(): Opens a file. Accepts a filename and a mode (e.g., 'r' for read, 'w' for write, 'a' for append).
• read(): Reads the entire file.
• readline(): Reads one line from the file.
• readlines(): Reads all lines into a list.
• write(): Writes a string to the file.
• writelines(): Writes a list of strings to the file.
• close(): Closes the file.
• with statement: Automatically closes the file after use, reducing errors. (recommended).

Python Modules

• math: Provides mathematical functions (e.g., sqrt, pi, factorial).
• os: Provides functions for interacting with the operating system.

Python JSON

• json.loads(): Parses a JSON string into a Python dictionary.
• json.dumps(): Converts a Python dictionary into a JSON string.

Error Handling (try, except, finally)

• try: Defines a block of code that might raise an exception.
• except: Defines a block of code that handles a specific type of exception.
• finally: Defines a block of code that runs regardless of whether an exception occurred.