Try...Except

3 tasks. Write the code, press Check, and the page runs it against a real Python interpreter.

Back to the try...except chapter

Exercise 1

Add up the numbers, skipping anything that will not convert, and print the total.

Python

values = ["10", "x", "30"]
total = 0
# add what you can
print(total)

values = ["10", "x", "30"]
total = 0
for text in values:
    try:
        total += int(text)
    except ValueError:
        pass
print(total)

Exercise 2

Return a different message for dividing by zero and for non-numbers.

Python

def divide(a, b):
    # handle both problems
    return a / b

print(divide(10, 2))
print(divide(10, 0))
print(divide(10, "x"))

def divide(a, b):
    try:
        return a / b
    except ZeroDivisionError:
        return "cannot divide by zero"
    except TypeError:
        return "those are not numbers"

print(divide(10, 2))
print(divide(10, 0))
print(divide(10, "x"))

Exercise 3

Print parsed on success, could not parse on failure, and done either way.

Python

def parse(text):
    # try, except, else and finally
    pass

parse("42")
parse("x")

def parse(text):
    try:
        value = int(text)
    except ValueError:
        print("could not parse")
    else:
        print("parsed", value)
    finally:
        print("done")

parse("42")
parse("x")