Python Basics

What is Python?

• Python is a high-level, interpreted programming language.
• Created by Guido van Rossum in 1991.
• Known for its simple, readable syntax that resembles English.
• Used for web development, data science, automation, AI, and more.

Installing Python

• Download from python.org (Python 3.x recommended).
• Check installation with 'python --version' or 'python3 --version'.
• Use pip to install packages: 'pip install package_name'.

# Check Python version
python --version

# Check pip version
pip --version

# Install a package
pip install requests

Running Python Code

• Interactive mode: Type 'python' in terminal for immediate execution.
• Script mode: Save code in .py file and run with 'python filename.py'.
• IDEs: Use VS Code, PyCharm, or Jupyter Notebook for development.

# Interactive mode
>>> print("Hello, World!")
Hello, World!

# Script mode (save as hello.py)
print("Hello, World!")
# Run: python hello.py

Comments

• Single-line comments start with #.
• Multi-line comments use triple quotes (''' or """).
• Comments explain code and are ignored by Python.

# This is a single-line comment

'''
This is a
multi-line comment
'''

x = 5  # Inline comment

Indentation

• Python uses indentation (spaces/tabs) to define code blocks.
• Standard is 4 spaces per indentation level.
• Consistent indentation is required - mixing causes errors.

# Correct indentation
if True:
    print("This is indented")
    print("Same level")

# Wrong - will cause IndentationError
if True:
print("Not indented")