Not making integer inputs

Question

I want a way for the user not to make an integer input by using this function:

x = input("Whats your name?") 
while x == int:
y = input("why is there a number in your name? Please re enter your name")

But this does not work. Any idea why?

this does not work I still enter an integer and the shell accepts it — mjick, May 14 '15 at 23:40
I know it's probably just a learning exercise, but for the future I wanted to refer you to [Falsehoods Programmers Believe About Names](http://www.kalzumeus.com/2010/06/17/falsehoods-programmers-believe-about-names/) - specifically "15. People’s names do not contain numbers." — viraptor, May 15 '15 at 00:06

Harshil Sharma · Answer 1 · 2015-05-15T23:38:52.050

2

Improving in @persian_dev's answer -

def check_name(string):
    for char in string :
        try:
            int(char)
            return False
        except:
            continue
    return True

This will traverse the string, try to convert each character to int and return False on first success in doing so.

edited May 15 '15 at 23:38

answered May 14 '15 at 23:59

Harshil Sharma

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score 1 · Answer 2 · edited May 23 '17 at 11:43

1

The input function will convert anything user enters to a string.

So you want to instead look whether there is any number contained in x, rather than the type.

See here: check if a string contains a number

edited May 23 '17 at 11:43

Community

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answered May 14 '15 at 23:43

Flying_Banana

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score 1 · Answer 3 · edited May 15 '15 at 00:03

1

here is a check function :

def isnumeric(string):
    try:
        int(string)
        return True
    except:
    return False

def check_name(string):
    for char in string:
        if isnumeric(char):
            return False
    return True

edited May 15 '15 at 00:03

Harshil Sharma

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answered May 14 '15 at 23:46

persian_dev

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The call to `isnumeric` from `check_name` for each character might be slow for performance. We can instead try the conversiotn of char to int in `check_name` itself. – Harshil Sharma May 14 '15 at 23:53
thanks thats a good point ... – persian_dev May 14 '15 at 23:57
1

And I guess you meant `string` instead of `str` in that for loop? – Harshil Sharma May 15 '15 at 00:00

score 1 · Answer 4 · answered May 15 '15 at 00:18

If you just want to make sure the user input contains strings only, you can use isalpha() to check the input:

x = raw_input("Whats your name?") 
while not x.isalpha():
    x = raw_input("why is there a number in your name? Please re enter your name")

I use Python 2 so I used raw_input instead of input. If you use Python 3 you can adjust accordingly.

Stefan Pochmann · Answer 5 · 2015-05-15T00:17:24.520

int is a type. You're not asking "Does x contain a number?" or even "Is x a number?", you're asking "Is x number?" (integer, more precisely). Makes no sense. Assuming entering names work, you're using Python 3, in which case the result of input is always a string. Even if it's a string of only digits. So isinstance(x, int) won't work, either. You could try casting with int(...), but that won't help if the name contains a number only somewhere among letters.

Here's a good way to test whether there's any digit in a string:

any(map(str.isdigit, x))

In your code, also with the y corrected to x:

x = input("Whats your name? ")
while any(map(str.isdigit, x)):
    x = input("why is there a number in your name? Please re enter your name ")

Not making integer inputs

5 Answers5