Lecture Notes: Python Programming Core Features

Introduction to Python

• Python is a versatile language used for data structures, algorithms, ML, AI, data science, and web development.
• Easier to learn compared to other languages, good for coding interviews.
• Interactive environment for learning through exercises and code editor.

Basic Printing

• Hello, World! is the traditional first program.
• Python uses the print function for displaying text.
• Can use double quotes or single quotes for strings.
• Case-sensitive and punctuation matters.
• Example: print('Hello, World!')

Python Fundamentals

• Python is an interpreted, high-level language created before JavaScript.
• Popular due to its modern syntax and readability.
• Used extensively in AI and ML.
• Focuses on core concepts suitable for both beginners and experienced programmers.

Variables and Data Types

• Variables are containers for data, defined using =.
• Common Data Types: int, float, bool, string, list.
• Dynamic typing: Variable types can change in Python.
• Variable naming rules: alphabetic characters, numbers, underscores; no starting digit or keyword names.

Comments

• Use # for single-line comments.
• Multiple line comments can be done using ''' or """.
• Comments are ignored during execution.

Control Flow

Conditional Statements

• if, else, elif for decision making.
• Example: if balance < 0: print('Overdrawn') else: print('In good standing')

Loops

• While loops: while condition: block of code
• For loops: Iterate over a sequence or range.
• Nested loops: Loops inside loops for multi-dimensional iterations.
• Example: for i in range(5): print(i)

Functions

• Defined using def keyword.
• Can accept parameters and return values.
• Example: def greet(name): return f'Hello, {name}'
• Type hints for readability, not enforced.
• Scope of variables: local vs global.

String Manipulation

• Strings are sequences of characters, immutable.
• Common operations: concatenation (+), slicing (:), reversing ([::-1]).
• Use len() for length, in for membership.
• String methods: split(), join(), replace().

Lists

• Lists are mutable sequences, defined using [].
• Can contain mixed data types, though not recommended.
• Common operations: append(), pop(), slicing, iteration.
• Use in for membership check.

Tuples

• Tuples are immutable sequences, defined using ().
• Useful for fixed collections of items.

Sets

• Unordered collections of unique elements, defined using {}.
• Common operations: add(), remove(), membership checks.

Dictionaries

• Collections of key-value pairs, defined using {key: value}.
• Keys must be unique, values can be of any type.
• Common operations: get(), pop(), iteration over keys or values.

Exception Handling

• Use try, except blocks to handle runtime errors.
• Specific exceptions can be caught using except ExceptionName:.
• finally block for cleanup, always runs.
• Example: try: result = 10/0 except ZeroDivisionError: print('Division by zero!') finally: print('This runs no matter what.')

Input/Output

• Use input() to read input, print() to display output.
• Convert input strings to other types using int(), float(), etc.
• Example: age = int(input('Enter age: ')) print(f'You are {age} years old')