5

Ive set up this program that checks the mark out of 100 for a test. If the user inputs less than 60 it should say fail if more than 59, pass.

mark = int(input("Please enter the exam mark out of 100 "))
if mark < 60:
    print("\nFail")
elif mark < 101:
    print("\nPass")
else:
    print("\nThe mark is out of range")

how do i get the program not to have errors if the user does not input the Integer.

Please help, is there a quick solution that 14 year olds would understand?

martineau
  • 119,623
  • 25
  • 170
  • 301
Tech484
  • 51
  • 1
  • 1
  • 2
  • If you're using python 2, use `raw_input` instead of `input`. Then follow one of the answers below. – kojiro Jul 11 '12 at 12:46
  • 1
    `If the user inputs less than 60 it should say fail if more than 59, pass.` So what is the passing score? 59.5? :) – Burhan Khalid Jul 11 '12 at 12:47

2 Answers2

6

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().

Simeon Visser
  • 118,920
  • 18
  • 185
  • 180
4
try:
   mark = int(input("Please enter the exam mark out of 100 "))
except ValueError:
   print("\nPlease only use integers")
Rob Wagner
  • 4,391
  • 15
  • 24