Check if input is a integer

Question

I am writing a program that will ask the user to enter in an integer, and if it is not an integer, i will print "Error" and exit the program.

I tried this:

userNumber = input()
try:
    val = int(userNumber)
except ValueError:
    print("Error")
    exit()

But this is not working and is giving me an error.

How can I fix this?

You have a few NameError's in your code. valueError should be ValueError and printf should be print. Also, your indentation is messed up. — user2555451
– user2555451, Commented Nov 9, 2014 at 20:18
Please don't change your code after the errors have been pointed out... — MattDMo
– MattDMo, Commented Nov 9, 2014 at 20:20
if i try entering the letter X i get the error: line 7, in <module> userNumber = input() File "<string>", line 1, in <module> NameError: name 'x' is not defined — user2955610
– user2955610, Commented Nov 9, 2014 at 20:23

Aaron Hall · Accepted Answer · 2014-11-09 20:31:30Z

2

You're using Python 2 I think this is what you're looking for, and if you want a real print function (like Python 3 has), include this import at the top of your header:

from __future__ import print_function

userNumber = raw_input() # `input` in python 3, 
                         # the `input` function in '2' is actually processed as Python.
                         # equivalent to eval(raw_input(prompt))
try:
    val = int(userNumber)
except ValueError:
    print("Error") # This is a print statement without the import in Python 2, 
                   # In which case the parentheses are ignored.
    exit()

In Python 2, input is equivalent to eval(raw_input(prompt)).

edited Nov 9, 2014 at 20:31

answered Nov 9, 2014 at 20:25

Aaron Hall♦

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1 Comment

Hackaholic Over a year ago

raw_input() not rawinput()

MattDMo · Accepted Answer · 2014-11-09 20:24:56Z

0

There are numerous problems with your program. The indentation is incorrect - the statements under try and except should be indented. Second, it's ValueError, not valueError. Third, you should be using print() instead of printf(). Finally, since you appear to be using Python 2, you should be using raw_input() instead of input().

edited Nov 9, 2014 at 20:24

answered Nov 9, 2014 at 20:19

MattDMo

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