Input, Types, Error Handling & GitHub

Learning Objectives

• Read user input with input() and inspect values with type().
• Perform basic type conversions using int(), float(), str(), and bool().
• Handle common input errors using try/except (e.g., ValueError, ZeroDivisionError).
• Set up a remote, connect a local repo to GitHub, and push the first commit.

Session Plan (theory)

1. Quick recap (local Git)
   Working directory, staging, commits (git status/add/commit/log).
2. Python: input & types
   • input() returns strings; check with type(value).
   • Casting: int("42"), float("3.14"), str(123), bool("any").
   • Trim before casting with .strip().
3. Basic error handling
   • try/except for invalid numeric input (ValueError).
   • Guard division by zero (ZeroDivisionError) and unknown operators.
   • Provide clear user feedback messages.
4. Git remotes & GitHub
   • Create a remote on GitHub.
   • Link and push:

     git remote add origin <repo-url>
     git branch -M main
     git push -u origin main
     

   • Basics of git clone for a new machine.

Hands-on

• Continue from Week 1 repo (or start a fresh one).
• Mini Project: Console Calculator v1.1 (with try/except)
  • Ask for two numbers and an operator (+, -, *, /).
  • Convert inputs safely with try/except ValueError.
  • Handle division by zero with try/except ZeroDivisionError.
  • Print a formatted result using an f-string (:.2f).

  Starter snippet ```python a_str = input(“First number: “).strip() b_str = input(“Second number: “).strip() op = input(“Operator (+, -, *, /): “).strip()

  try: a = float(a_str) b = float(b_str) except ValueError: print(“Invalid number. Please enter numeric values (e.g., 3 or 3.5).”) raise SystemExit(1)

  try: if op == “+”: result = a + b elif op == “-“: result = a - b elif op == “*”: result = a * b elif op == “/”: result = a / b # may raise ZeroDivisionError else: print(“Unsupported operator. Use one of: +, -, *, /”) raise SystemExit(1) except ZeroDivisionError: print(“Error: division by zero.”) raise SystemExit(1)

  print(f”Result: {a:.2f} {op} {b:.2f} = {result:.2f}”)