🚨 Introduction

Errors: When Things Go Wrong

Every programmer, no matter how experienced, writes code that breaks. That's completely normal! The skill isn't in writing perfect code — it's in knowing how to handle when things go wrong, so your program doesn't just crash and die dramatically.

Errors are not your enemies. They're Python telling you exactly what went wrong and where. Learning to read them is a superpower! 🦸

🔍 Types of Errors

Not all errors are the same

Python has three main categories of errors. Each is a sign of something different going wrong.

❶ Syntax Error

You typed Python code incorrectly — like a grammatical mistake. Python can't even read it. It will refuse to run the program at all.

# Missing the colon!
if x > 5
    print("Big")   # SyntaxError!

❷ Runtime Error

The code looks fine, but something goes wrong while it's running. For example, trying to divide by zero or accessing a list index that doesn't exist.

result = 10 / 0  # ZeroDivisionError!

❸ Logic Error

The hardest to find! Python runs the code perfectly without any complaint, but the result is wrong because your logic was off.

# Trying to get the average, but logic is wrong!
total = 90 + 80 + 70
average = total / 2   # Should be / 3!
print(average)        # Runs fine, but prints 120 not 80!

🛡️ try / except

Catching errors before they crash everything

For runtime errors, Python gives you the try / except blocks. You put the "risky" code inside try. If an error occurs, instead of crashing, Python jumps straight into the except block where you can handle it gracefully.

safe_divide.py
try:
    number = int(input("Enter a number: "))
    result = 100 / number
    print("Result is:", result)

except ZeroDivisionError:
    print("Oops! You can't divide by zero.")

except ValueError:
    print("That's not a valid number!")try:Everything indented here is the "risky zone". Python will attempt to run it.
except ZeroDivisionError:If a zero-division error happens, run this block instead of crashing. You can have multiple except blocks for different errors!

✅ else & finally

The full error-handling toolkit

else: Runs if the try block succeeded with no errors.
finally: Always runs, no matter what — whether an error happened or not. Great for cleanup actions like closing a file.

try:
    result = 100 / 5
except ZeroDivisionError:
    print("Error!")
else:
    print("Success! Result is:", result)  # Runs if no error
finally:
    print("Attempted division.")  # Always runs!

💡 Real-Life Analogy

Think about a tightrope walker performing above a circus tent.

try: The walker steps onto the rope and attempts to cross.
except: There's a safety net underneath. If they fall (an error), they land in the net instead of hitting the ground.
finally: After crossing OR falling, the crowd always applauds. That applause always happens no matter what.

🖼️ Diagram

The try/except Flow

If an error occurs, execution jumps straight to except. Either way, finally always runs last.

😂 Sarpanch's Corner

The Spellcheck

Panel 1

"I'll write code to print a friendly message!"

pritn("Hello!")

Panel 2

"NameError: name 'pritn' is not defined"

He spelled print as pritn 😬

Panel 3

"Every single beginner makes this exact mistake. And most experienced developers have too. Welcome to the club."

🚀 Try It Yourself

Catching Errors Safely

Run this code, then try causing different errors to see how the except blocks catch them.

💡 Challenges:

Change number = 5 to number = 0 and run again. See the error message?
Change number = 5 to number = "hello" and run again. A different error is caught!
Add a finally: block at the end that always prints "Division attempt complete."

✅ Summary

Handling Trouble — Done! 🛡️

Syntax Errors: You typed code wrong. Python refuses to run at all.
Runtime Errors: Code looks fine but crashes during execution (e.g., dividing by zero).
Logic Errors: Code runs fine, but produces the wrong result. Hardest to find!
Use try / except to catch runtime errors gracefully instead of crashing.
else: runs only if no error occurred in the try block.
finally: always runs, with or without an error. Perfect for cleanup.

Your code is now crash-proof! You have a safety net under every tightrope walk. Next up we learn to read and write actual files on your computer! 📄