Error handling using integers as input

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Save the input in a variable and convert to an integer separately:

import sys

i = input("Please enter the exam mark out of 100 ")
try:
    mark = int(i)
except ValueError:
    print('\nYou did not enter a valid integer')
    sys.exit(0)
if mark < 60:
    print("\nFail")
elif mark < 101:
    print("\nPass")
else:
    print("\nThe mark is out of range")

If it fails (i.e., you get a ValueError) then print a message and exit. You can explain (to a 14-year old) that int() needs a valid integer as input and it will raise a ValueError otherwise. That makes sense because only strings that contain an integer can be converted by int().

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