Bug type: Runtime

The int(raw) call happens outside the try, so a non-numeric entry raises ValueError before the except can catch it and the program crashes. Move the conversion inside the try so the failing line is actually protected.

while True:
    raw = input("Enter your age in years: ")
    try:
        age = int(raw)
        print("Your age is", age)
        break
    except ValueError:
        print("That was not a whole number. Try again.")

Back to Exercise 16.1.1 · sol_16_1_1.py

Bug type: Runtime

The exception name is misspelled VlaueError, which Python treats as an unknown name; when float raises the real ValueError it is not caught and the program crashes (and the wrong name itself raises NameError). Spell it ValueError.

try:
    price = float(input("Enter a price in dollars: "))
    print("Two of those cost", 2 * price)
except ValueError:
    print("That was not a valid price.")

Back to Exercise 16.1.2 · sol_16_1_2.py

Bug type: Logical

There is no break after a successful read, so even on valid input the while True loop never ends — it keeps re-asking forever. Add break once a valid count is printed.

while True:
    try:
        beans = int(input("How many jellybeans? "))
        print("There are", beans, "jellybeans.")
        break
    except ValueError:
        print("Please type a whole number.")

Back to Exercise 16.1.3 · sol_16_1_3.py

Bug type: Syntax

The except ValueError line is missing its colon, so the file will not parse. Add the colon.

try:
    celsius = float(input("Temperature in Celsius? "))
    fahrenheit = celsius * 9 / 5 + 32
    print("That is", fahrenheit, "degrees Fahrenheit.")
except ValueError:
    print("That was not a valid number.")

Back to Exercise 16.1.4 · sol_16_1_4.py

Bug type: Logical

The except block silently keeps the invalid text by assigning score = raw, so the program reports nonsense as a score instead of rejecting it. Validation should re-prompt or refuse bad input rather than swallow it.

while True:
    raw = input("Enter your test score: ")
    try:
        score = int(raw)
        break
    except ValueError:
        print("Please type a whole number.")
print("Your score is", score)

Back to Exercise 16.1.5 · sol_16_1_5.py

Bug type: Runtime

Dividing by zero raises ZeroDivisionError, but the code catches ValueError, so the real error escapes and the program crashes. Catch ZeroDivisionError.

bill = 60.0
friends = 0
try:
    share = bill / friends
    print("Each person pays", share)
except ZeroDivisionError:
    print("There must be at least one person.")

Back to Exercise 16.2.1 · sol_16_2_1.py

Bug type: Runtime

Adding an integer to a string raises TypeError, but the code catches ZeroDivisionError, so the error is not caught and the program crashes. Catch TypeError.

total = 100
new_value = "twelve"
try:
    total = total + new_value
except TypeError:
    print("That measurement was not a number.")
print("Total is", total)

Back to Exercise 16.2.2 · sol_16_2_2.py

Bug type: Logical

The broad except Exception is listed first, and because ZeroDivisionError is a subclass of Exception, the first handler swallows a zero-time error and prints the misleading “Distance was not a number” message; the specific ZeroDivisionError handler is unreachable. Put the specific handler before the general one.

distance = float(input("Distance in meters? "))
time = float(input("Time in seconds? "))
try:
    speed = distance / time
    print("Average speed:", speed)
except ZeroDivisionError:
    print("Time cannot be zero.")
except Exception:
    print("Distance was not a number.")

Back to Exercise 16.2.3 · sol_16_2_3.py

Bug type: Runtime

Looking up a missing dictionary key raises KeyError, but the code catches ValueError, so the lookup failure is not handled and the program crashes. Catch KeyError.

grades = {"Ann": 91, "Bo": 84}
name = "Cleo"
try:
    print(name, "scored", grades[name])
except KeyError:
    print("No grade recorded for", name)

Back to Exercise 16.2.4 · sol_16_2_4.py

Bug type: Logical

The broad except Exception comes first, and since ZeroDivisionError is a subclass of Exception, a zero divisor is caught by the first handler and reported as “not a valid number”; the specific ZeroDivisionError handler can never run. List the specific handler before the general one.

price = 50
divisor = input("Divide the discount by? ")
try:
    fraction = 100 / int(divisor)
    print("You pay", price * fraction)
except ZeroDivisionError:
    print("The divisor cannot be zero.")
except Exception:
    print("That was not a valid number.")

Back to Exercise 16.2.5 · sol_16_2_5.py

Bug type: Logical

The success line is printed twice — once inside try and again in else. Code that should run only on success belongs in else, not in try; remove the duplicate from the try block.

text = "42"
try:
    number = int(text)
except ValueError:
    print("That was not a number.")
else:
    print("Conversion worked:", number)

Back to Exercise 16.3.1 · sol_16_3_1.py

Bug type: Logical

The else block computes area but never prints it, so the program produces no visible result on success. Print the area in the else block.

try:
    width = float(input("Width? "))
    height = float(input("Height? "))
except ValueError:
    print("Both sides must be numbers.")
else:
    area = width * height
    print("Area:", area)

Back to Exercise 16.3.2 · sol_16_3_2.py

Bug type: Logical

The doubling work that should run only after a successful conversion is placed in the try block; if cups * 2 or the print logic ever failed it would be wrongly treated as an input error. The success-only computation belongs in else, leaving only the risky conversion in try.

try:
    cups = float(input("How many cups? "))
except ValueError:
    print("That was not a number.")
else:
    doubled = cups * 2
    print("You need", doubled, "cups.")

Back to Exercise 16.3.3 · sol_16_3_3.py

Bug type: Syntax

The try keyword is missing its colon, so the file will not parse. Add the colon after try.

import math

try:
    value = float(input("Enter a number: "))
except ValueError:
    print("That was not a number.")
else:
    print("Square root is", math.sqrt(value))

Back to Exercise 16.3.4 · sol_16_3_4.py

Bug type: Logical

The tax formula uses addition (amount + 0.08) instead of multiplication, so it adds eight cents rather than computing 8 percent of the amount. Use amount * 0.08.

try:
    amount = float(input("Purchase amount? "))
except ValueError:
    print("That was not a number.")
else:
    tax = amount * 0.08
    print("Tax is", tax)

Back to Exercise 16.3.5 · sol_16_3_5.py

Bug type: Logical

The closing line sits inside the except block, so it prints only when the division fails; on the normal path it never runs. Move the always-run line into a finally block.

try:
    result = 10 / 2
    print("Result:", result)
except ZeroDivisionError:
    print("Cannot divide by zero.")
finally:
    print("Done with the calculation.")

Back to Exercise 16.4.1 · sol_16_4_1.py

Bug type: Logical

“Scale released” must always print, but it is in the else block, which runs only when no exception occurs; on bad input it is skipped. Use finally so it runs whether or not an error happened.

try:
    weight = float(input("Weight in kilograms? "))
    print("Recorded weight:", weight)
except ValueError:
    print("That was not a number.")
finally:
    print("Scale released.")

Back to Exercise 16.4.2 · sol_16_4_2.py

Bug type: Syntax

The finally keyword is missing its colon, so the file will not parse. Add the colon after finally.

try:
    count = int(input("How many items? "))
    print("Count:", count)
except ValueError:
    print("Not a whole number.")
finally:
    print("Attempt logged.")

Back to Exercise 16.4.3 · sol_16_4_3.py

Bug type: Logical

The tally line sits inside the try right after the division, so a ZeroDivisionError skips it. A line that must always run belongs in a finally block, which executes whether or not an exception occurs.

points = 90
rounds = 0
try:
    average = points / rounds
    print("Average:", average)
except ZeroDivisionError:
    print("No rounds played.")
finally:
    print("Final tally complete.")

Back to Exercise 16.4.4 · sol_16_4_4.py

Bug type: Syntax

The clauses are out of order: finally appears before except, which is not allowed — except (and else) must come before finally. Reorder so except precedes finally.

try:
    distance = float(input("Distance in meters? "))
    print("Distance:", distance)
except ValueError:
    print("That was not a number.")
finally:
    print("Sensor reset.")

Back to Exercise 16.4.5 · sol_16_4_5.py