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Starter Notes

Updated Oct 28, 2019 ·

Install Python​

For Windows:

  1. Download Python:

  2. Run the Installer:

    • Open the downloaded .exe file.
    • On the installer screen, check the box for "Add Python to PATH" at the bottom.
    • Click on "Install Now."

  3. Verify Installation:

    • Open Command Prompt (cmd) and type: 
      python --version

  4. Install pip (if needed):

    • pip, Python’s package installer, comes with Python 3.x. To verify, type: 
      pip --version

For other OS, please see official documentation.

Running a Python script​

If you have script, you can run it by:

python3 script-name.py

Functions and Keywords​

Functions perform specific tasks in code.

  • Example: print() outputs a message to the screen.

Keywords are reserved words used to form instructions in Python.

  • Examples: for, in, if, def.
  • Full list includes: False, True, None, return, break, etc.

Implicit vs. Explicit Conversion​

  • Implicit Conversion: Automatic type conversion by the interpreter.
  • Explicit Conversion: Manual conversion using functions (e.g., str()).

Defining Functions​

To define functions:

  • Use def followed by the function name and parameters in parentheses.
  • Indented code following the colon, using consistent spacing.

Use return to send data back to the caller. Functions can return several values; ensure to store them appropriately.

Recursion​

Recursive Functions call themselves with modified parameters and must have a base case to stop the recursion.

def recursive_function(n):
    if n <= 1:  # Base case
        return 1
    else:
        return n * recursive_function(n - 1)  # Recursive case

Common Pitfalls​

Reminders:

  • Uninitialized variables can lead to NameError.
  • Ensure proper initialization before use.
  • Infinite loops occur when loop conditions never change.
  • Error messages may indicate timeout due to infinite loops.

Use the code below to get website statue:

import requests
response = requests.get("https://youtube.com")
print(response)

Run the code:

python3 get-website-status.py

Output:

<Response [200]>