Exceptions

Questions 1 to 5 of 6

1. 1. Predict the output of this program. ``python def check(x): try: if x < 0: raise ValueError(f"negative: {x}") return x * 2 except ValueError as err: print("caught", err) return -1 finally: print("finally", x) print(check(4)) print(check(-2)) ``

   finally 4 8 caught negative: -2 finally -2 -18 caught negative: -2 -1caught negative: -2 finally -2 -1 finally 4 8finally 4 8 caught negative: -2 -1 finally -2
2. 2. Predict the output of this program. The transfer method checks everything before it changes any balance. ``python class Account: def __init__(self, balance): self.balance = balance def transfer(self, to, amount): if amount <= 0: raise ValueError("bad amount") if amount > self.balance: raise RuntimeError(f"short by {amount - self.balance}") self.balance -= amount to.balance += amount a = Account(100) b = Account(0) try: a.transfer(b, 30) a.transfer(b, 500) except RuntimeError as err: print(err) print(a.balance, b.balance) ``

   short by 470 70 30short by 430 100 0short by 430 70 30short by 430 30 70
3. 3. A caller passes a negative withdrawal amount, which is a mistake in the caller's code. Following the lesson, which exception fits?

   ValueError, because the amount is simply wrong and the caller should fix its codeInsufficientFundsError, a custom exception that the caller can catch and recover fromNone, returned from the method as a value that means nothingA return value of -1, with no exception raised
4. 4. A function raises an exception, and its caller does not catch it. What happens in Python? ``python def withdraw(amount): if amount < 0: raise ValueError("negative amount") return amount withdraw(-1) print("not reached") ``

   Python refuses to compile the file until the caller catches the errorThe error is ignored silently, and the program prints not reachedPython turns the error into a return value of -1The file compiles, and the error appears only when that line runs, stopping the program with a traceback
5. 5. Put these steps in the order that Python follows after a function raises an exception.

   Use the arrows to put the steps in order.

   1. 1.Python looks for a matching except block in the current function↑↓
   2. 2.If no handler is found anywhere, Python prints a traceback and stops the program↑↓
   3. 3.If no except block matches, Python leaves the function and looks in the caller↑↓
   4. 4.The normal flow stops, and the code after the raise does not run↑↓