Check if input is positive integer [duplicate]

Question

I need to check whether what the user entered is positive. If it is not I need to print an error in the form of a msgbox.

number = input("Enter a number: ") ################################### try: val = int(number) except ValueError: print("That's not an int!")

The above code doesn't seem to be working.

Any ideas?

after getting val, check it if it's greater than 0. if so, throw another exception. — Jason Hu
– Jason Hu, Commented Oct 4, 2014 at 23:26
Traceback (most recent call last): File "C:\Users\Office\Desktop\Python\If Else\Program\program.py", line 4, in <module> number = input("Enter a number: ") File "<string>", line 1, in <module> NameError: name 'hi' is not defined — shivampaw
– shivampaw, Commented Oct 4, 2014 at 23:30

Padraic Cunningham · Accepted Answer · 2015-04-04 22:01:20Z

25

while True: number = input("Enter a number: ") try: val = int(number) if val < 0: # if not a positive int print message and ask for input again print("Sorry, input must be a positive integer, try again") continue break except ValueError: print("That's not an int!") # else all is good, val is >= 0 and an integer print(val)

edited Apr 4, 2015 at 22:01

answered Oct 4, 2014 at 23:32

Padraic Cunningham

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7 Comments

shivampaw Over a year ago

Nope............. still same error.

Padraic Cunningham Over a year ago

there is no error in my code and what error are you talking about?

shivampaw Over a year ago

My full code: pastebin.com/yctSQLz0

Padraic Cunningham Over a year ago

I have answered your question as posted, if you have another problem you should ask another question and fyi your code you posted in pastebin works fine

Lukas Graf Over a year ago

@shivampaw that isn't even remotely related to the code that Padraic posted (or the traceback you posted, for that matter).

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W1ll1amvl · Accepted Answer · 2014-10-04 23:37:17Z

what you need is something like this:

goodinput = False while not goodinput: try: number = int(input('Enter a number: ')) if number > 0: goodinput = True print("that's a good number. Well done!") else: print("that's not a positive number. Try again: ") except ValueError: print("that's not an integer. Try again: ")

a while loop so code continues repeating until valid answer is given, and tests for the right input inside it.

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