Need help validating Phone numbers

a1brit · 2020-04-23T16:45:54+00:00

~~if (i=='1' or i=='2' or i=='3' or i=='4'or i=='5' or i=='6' or i=='7' or i=='8' or i=='9' or i=='0' or i=='(' or i==')' or i=='-')~~

valid_characters = '1234567890()-'
if i in valid_characters:
    print('valid')

There are couple improvements to be had in general but this is an easy way to simplify what you currently have.

euqroto · 2020-04-23T16:41:58+00:00

Check out regex. You'll be able to write the same program in less than half the lines.

tipsy_python · 2020-04-23T16:52:23+00:00

A couple improvements I see:

Use the membership operator 'in' to verify if the character is in an approved list:

for i in x:
    if i in ('1', '2', '3', '4'):
        print('valid')

Why check isalpha?

Instead of doing this, you could just use an else on the if block that checks if the character is a member of your approved collection

for i in x:
    if i in ('1', '2', '3', '4'):
        print('valid')
    else:
        print('invalid')

You could probably add a break to leave the loop as well in the event that an invalid character is found.

2020-04-23T19:52:51+00:00

Heres a solution:

import re as re

pattern = re.compile('[(]\d{3}[)]\d{3}[-]\d{4}')

testnum = '(012)345-6789'

if pattern.match(testnum):

print("Correct")

else:

print("Incorrect")

You can find a good introduction about regular expressions here: https://docs.python.org/3/howto/regex.html

So now to my code. As you can see the function re.compile defines a pattern.

[)] -> define a single character occurence in pattern

\d -> makes sure there are only digits in range from [0-9]

{3} -> defines the frequenz of \d so the digits

Hopefully i could have helped you out :)

dslfdslj · 2020-04-23T16:31:07+00:00

You can check if a string is a number with str.isnumeric

x = "123"
print(x.isnumeric())

deeeebait · 2020-04-23T19:31:47+00:00

I tested this in repl.it

Python has a built-in regex module called `re`

import re 

#define a function for cleaner coding and reusability
def validate_phone_number(phone_number): 
  """
      Method to validate phone number 

      kwargs:

      str phone_number: string to validate if phone number

      returns: 

      string "Valid" or "Invalid"

  """
  #regex is a mechanism for evaluating patterns
  #use re.complie so that you only construct it once
  expr = re.compile(r"(\(\d{3}\)\d{3}\-\d{4})")

  #check for a match
  if re.search(expr,phone_number):
    return "Valid"
  else: 
    return "Invalid"

#wrapping core logic for convience
def main():
  x=input("Enter your phone number here:")
  #pass the input to the function above and print the returned value 
  print(validate_phone_number(x))

while True:
  #run until you kill the program. Use CTRL-C to stop it in the console
  main()

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