try and except

Python · Unit 9: Errors and exceptions

Full plan
Python
10 exercises

try tries a block. If an error of the type you name in except crashes in there, Python doesn't stop: it jumps to the except and then carries on with what's below.

try:
    print(10 / 0)
except ZeroDivisionError:
    print("Can't divide by 0")
print("The program goes on")

Prints

Can't divide by 0
The program goes on

The rest of the explanation is in the lesson, which is part of the full plan.

Exercises in this lesson

You do them in the app, which checks them on the spot and explains why.

1. Predict the output
What does this code print?
2. Predict the output
What does this code print?
3. Complete the code
The person types three, in letters. Complete it so the program doesn't crash.
4. Complete the code
Complete it so it warns you instead of crashing.
5. Find the bug
This program should say there's no third number. Which line has the bug?
6. Multiple choice
text is a number, but the program says «Numbers only». Why?
7. Predict the output
The person types ten, in letters. What does it print?
8. Put the lines in order
The person types two, in letters, and then 2. Put the program in order so it asks for tickets until it gets a number.
9. Find the case that fails
to_int(t) should turn the text into a whole number, or return 0 if it isn't a number. Which call breaks it?
10. Predict the output
There's a typo in the list. What does it print?

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