Class Notes: Introduction to Python Programming

1. History of Python

• Creator: Python was created by Guido Van Rossum.
• Release Date: The language was released in February 1991.
• Name Origin: Python got its name from a BBC comedy series from the 1970s called “Monty Python’s Flying Circus.”

2. Python’s Programming Approach

• Procedural and Object-Oriented: Python supports both Procedural and Object-Oriented approaches to programming, making it versatile for various types of applications.
• Free to Use: Python is free and open-source, meaning anyone can use and modify it without cost.

3. Influences on Python

• ABC Language: Python is influenced by the ABC language, which was designed as a replacement for BASIC.
• Modula-3: Another significant influence on Python is Modula-3, which contributed to Python’s design.

4. Applications of Python

Python is used in many diverse fields, including:

• Scripting
• Web Applications
• Game Development
• System Administration
• Rapid Prototyping
• GUI Programs
• Database Applications

5. Python Distributions

• CPython: The default installation available from python.org is called CPython, which includes the Python interpreter, Python IDLE (Python GUI), and Pip (package installer).
• Anaconda: Anaconda is a highly recommended distribution that comes with many preloaded packages and libraries like NumPy, SciPy, and Pandas.
• Popular IDEs: IDEs like Spyder and PyCharm are popular for Python development. Spyder is available as part of the Anaconda distribution.

6. Python Working Modes

• Interactive Mode:
  • Python executes commands immediately after they are entered.
  • Commands are typed at the IDLE prompt (>>>), and Python provides instant feedback.
• Script Mode:
  • Multiple commands are saved in a file, and the entire program can be executed at once.
  • Script mode is ideal for writing longer pieces of code that need to be saved and reused.

7. Interactive Mode Example

• Command:
  • Typing >>> 20 + 30 at the IDLE prompt will output 50.
• Script Mode Example:
  • A simple Python program to print “Hello World!” is written in a file and executed to see the output.

8. Printing in Python

• Python 3.x: Uses the print() function to display output.
  • Example: print("Welcome to Python") will display “Welcome to Python.”
• String Enclosures: Python allows both single and double quotes for enclosing strings, but the opening and closing quotes must match.
  • Example: print('Python rocks!') will display “Python rocks!”

9. Key Points to Remember

• Case-Sensitivity: Python is case-sensitive, treating m and M as different entities.
• Recall Commands: Use the up (↑) and down (↓) arrow keys to recall and execute previous commands in interactive mode.
• Interactive vs. Script Mode:
  • Interactive Mode: Best for beginners and testing small pieces of code.
  • Script Mode: Best for writing and saving longer programs.

10. Sample Python Code

• Comment: Lines starting with # are comments and are ignored by the interpreter.
• Output: The script above will output “Hello World!”

11. Questions for Review

• Who developed the Python programming language?
• Is Python an object-oriented language?
• What does it mean that Python is a high-level interpreted language?
• What does cross-platform mean?
• What is the difference between interactive mode and script mode in Python?