How to validate floating numbers in isdigit() in python

Question

I am trying to validate a user input, and the user input is required to be positive integers including floating point numbers. I tried with isdigit(), it validated all the non-numeric inputs and negative integers as well but could not validate the floating point numbers. Below is my code

 def is_number(s):
     while (s.isdigit() == False):
       s = input("Enter only numbers, not less than 0 : ")
 return float(s)

#method call

 while('true'):
      membershipFee = is_number(input('Enter the base membership fee, or zero to quit: '))

Should a floating point number return float or int. If int should it always round down? — tdelaney
– tdelaney, Commented Aug 16, 2020 at 2:57

tdelaney · Accepted Answer · 2020-08-16 03:15:19Z

1

You can try the conversion and catch any errors. If python's happy, you're happy.

def is_number(s):
    while True:
        try:
            retval = float(s)
            if s >= 0.:
                return s
        except ValueError:
            pass
        s = input("Enter only numbers, not less than 0 : ")

edited Aug 16, 2020 at 3:15

answered Aug 16, 2020 at 2:58

tdelaney

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jreiss1923 · Accepted Answer · 2020-08-16 02:43:43Z

0

If you want to use isdigit(), you can't use it on a float. One possible solution is to use a regex to validate your floats.

Using isdigit for floats?

answered Aug 16, 2020 at 2:43

jreiss1923

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Joe Ferndz · Accepted Answer · 2020-08-16 03:49:08Z

0

You can try to do something like this:

#check if there is only one decimal place and check if it is not negative
s = input('Enter the number :')
if s.replace('.','',1).isdigit() and '-' not in s:
    print ('OK to process')
else:
    print ('not OK to process')

This will ensure that you will have the kind of numbers you need.

answered Aug 16, 2020 at 3:49

Joe Ferndz

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Kuldip Chaudhari · Accepted Answer · 2020-08-16 04:22:15Z

0

You should try this

def isNumber(f):
    return all([p.isdigit() for p in [f[:f.find('.')], f[f.find('.')+1:]] if len(p)])

print(isNumber('12.543'))
print(isNumber('185'))
print(isNumber('.2341'))
print(isNumber('163.'))
print(isNumber('14.356.67'))

answered Aug 16, 2020 at 4:22

Kuldip Chaudhari

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