How do I compare a string and an integer in Python?

Question

I am quite a newbie in Python. I wrote this and got this error when i typed a letter in the input:

TypeError: unorderable types: str() >= int()

Here is the code that I wrote:

user_input = input('How old are you?: ')
if user_input >= 18:
   print('You are an adult')
elif user_input < 18:
     print('You are quite young')
elif user_input == str():
     print ('That is not a number')

it should be `user_input = int(input('How old are you?: '))` — styvane, Nov 28 '15 at 23:28
Thanks but this time it says: ValueError: invalid literal for int() with base 10: 'a' — Keretto, Nov 28 '15 at 23:31
`elif user_input == str()` is _not_ how you say "if `user_input` can't be parsed as some kind of number." Please read the [official Python tutorial](https://docs.python.org/3.4/tutorial/index.html). — TigerhawkT3, Nov 29 '15 at 00:41

score 8 · Answer 1 · edited Nov 28 '22 at 03:16

8

You should do:

user_input = int(input('How old are you?: '))

so as you explicitly cast your input as int, it will always try to convert the input into an integer, and will raise a ValueError when you enter a string that can't be converted to an int. To handle those cases, do:

except ValueError:
    print('That is not a number')

So, the full solution might be like below:

try:
    user_input = int(input('How old are you?: '))
except ValueError:
    print('That is not a number')
else:
    if user_input >= 18:
        print('You are an adult')
    else:
        print('You are quite young')

edited Nov 28 '22 at 03:16

wjandrea

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answered Nov 28 '15 at 23:36

Ahsanul Haque

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Thanks everyone I understand what you mean but it is saying invalid syntax now (except ValueError:) – Keretto Nov 28 '15 at 23:45

score 1 · Answer 2 · edited Nov 28 '15 at 23:30

1

user_input is a str, you're comparing it to an int. Python does not know how to do that. You will need to convert one of them to the other type to get a proper comparison.

For example, you can convert a string to an integer with the int() function:

user_input = int(input('How old are you?: '))

edited Nov 28 '15 at 23:30

Andrea

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answered Nov 28 '15 at 23:29

bperson

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score 0 · Answer 3 · answered Nov 28 '15 at 23:39

0

user_input = input('How old are you?: ')
try:
    age = int(user_input)
except ValueError:
    print('Please use an integer for age')
    continue          # assuming you have this is an input loop
if user_input < 18:
     print('You are quite young')

answered Nov 28 '15 at 23:39

ennuikiller

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How do I compare a string and an integer in Python?

3 Answers3

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