Validating credit card

[frequency]

Hello,
I have been trying to make a credit card validator but i keep getting an error. I have created a special fuction that removes the empty spaces and "-"s from the string.

def checker(string):
  for i in range (len(string)):
    if " " in string:
      string = string.replace(' ','')   
    elif "-" in string:
      string = string.replace('-','')  

This is my total code

def digit_sum(LIST):
    for i in range(len(LIST)):
      value = str(LIST[i])
      digits = [int(x) for x in value]
      credit_card.append(sum(digits))

def checker(string):
  for i in range (len(string)):
    if " " in string:
      string = string.replace(' ','')   
    elif "-" in string:
      string = string.replace('-','')  
      

credit_card=[]
credit_card_sum=[]
credit_card_sum_digit=[]
credit_digits_sum=0    



user_input=input()
checker(user_input)
while user_input!="end" and user_input!="END":  
   
   credit_card_str=str(user_input)
  
   credit_card_int=[int(x) for x in credit_card_str]
   if credit_card_int[0]<4 or credit_card_int[0]>7:
     
     print ("False")
   else:
    for i in range(len(credit_card_int)):
      if not (i% 2):
        credit_card_int[i] = credit_card_int[i]*2
    digit_sum(credit_card_int)
    for i in range(len(credit_card)):
      credit_digits_sum=credit_digits_sum+credit_card[i]
    if credit_digits_sum % 2 ==0:
     print ("True")
    else:
     print ("False")
   user_input=input()  

If you try to run in with the input 5497-3571-7063-2130 or 54 97357 170632 130 You will get an error like this. Should i reconvert the string to STR?

[gontajones]

You have to return the new (modified) string.

def checker(string):
  for i in range (len(string)):
    if " " in string:
      string = string.replace(' ','')   
    elif "-" in string:
      string = string.replace('-','')
  return string

A better way to write this function:

def checker(s):
  return s.replace(' ','').replace('-','')

The replace() already search in every char of the string.

[frequency]

When running the program python breaks on line

credit_card_int=[int(x) for x in user_input] 

error code

Traceback (most recent call last):
  File "python", line 22, in <module>
  File "python", line 22, in <listcomp>
ValueError: invalid literal for int() with base 10: ' '

[gontajones]

This is happening because your not actually removing the ' ' and/or '-' from input.
Try this:

def digit_sum(LIST):
    for i in range(len(LIST)):
      value = str(LIST[i])
      digits = [int(x) for x in value]
      credit_card.append(sum(digits))
 
def checker(s):
  return s.replace(' ','').replace('-','')
       

credit_card=[]
credit_card_sum=[]
credit_card_sum_digit=[]
credit_digits_sum=0    

user_input=input()
user_input = checker(user_input) # <===== HERE
while user_input!="end" and user_input!="END":  
    
   credit_card_str=str(user_input)
   
   credit_card_int=[int(x) for x in credit_card_str]
   if credit_card_int[0]<4 or credit_card_int[0]>7:
      
     print ("False")
   else:
    for i in range(len(credit_card_int)):
      if not (i% 2):
        credit_card_int[i] = credit_card_int[i]*2
    digit_sum(credit_card_int)
    for i in range(len(credit_card)):
      credit_digits_sum=credit_digits_sum+credit_card[i]
    if credit_digits_sum % 2 ==0:
     print ("True")
    else:
     print ("False")
   user_input=input()
   user_input = checker(user_input) # <===== HERE

[frequency]

Thank you for your reply. I am getting the same error.

[b]Traceback (most recent call last):
  File "python", line 18, in <module>
  File "python", line 18, in <listcomp>
ValueError: invalid literal for int() with base 10: '-'[/b]

After this my goal is to make the program print "False" when it detects other user inputs like these "5497.3571,7063*2130".So i must exclude dots,commas and asterisks,and weird inputs like these "54 97357 170632 130"

[gontajones]

Could you please post your current code?
Because line 18 in my code is while user_input!="end" and user_input!="END":.
And in yours seems to be credit_card_int=[int(x) for x in credit_card_str].

[frequency]

Yea,sorry for this. I keep on making many versions of the code so i keep experimenting. Take my code

def digit_sum(LIST):
    for i in range(len(LIST)):
      value = str(LIST[i])
      digits = [int(x) for x in value]
      credit_card.append(sum(digits))
  
def checker(s):
  return s.replace(' ','').replace('-','')
        
 
credit_card=[]
credit_card_sum=[]
credit_card_sum_digit=[]
credit_digits_sum=0    
 
user_input=input()
user_input = checker(user_input) # <===== HERE
while user_input!="end" and user_input!="END":  
     
   credit_card_str=str(user_input)
    
   credit_card_int=[int(x) for x in credit_card_str]
   if credit_card_int[0]<4 or credit_card_int[0]>=7:
       
     print ("False")
   else:
    for i in range(len(credit_card_int)):
      if not (i% 2):
        credit_card_int[i] = credit_card_int[i]*2
    digit_sum(credit_card_int)
    for i in range(len(credit_card)):
      credit_digits_sum=credit_digits_sum+credit_card[i]
    if credit_digits_sum % 2 ==0:
     print ("True")
    else:
     print ("False")
   user_input=input()
   user_input = checker(user_input) # <===== HERE

[frequency]

Changed code to

def digit_sum(LIST):
    for i in range(len(LIST)):
      value = str(LIST[i])
      digits = [int(x) for x in value]
      credit_card.append(sum(digits))

def checker(s):
    list_of_numbers=[]
    string_to_use=""
    if("-" in s):
        list_of_numbers=s.split("-")
        for character in list_of_numbers:
            string_to_use+=character
        string_return=string_to_use
        string_to_use=""
        return string_return
    if(" " in s):
        list_of_numbers=s.split(" ")
        for character in list_of_numbers:
            string_to_use+=character
        string_return=string_to_use
        string_to_use=""
        return string_return
    if("," in s):
        list_of_numbers=s.split(",")
        for character in list_of_numbers:
            string_to_use+=character
        string_return=string_to_use
        string_to_use=""
        return string_return
    if("*" in s):
        list_of_numbers=s.split("*")
        for character in list_of_numbers:
            string_to_use+=character
        string_return=string_to_use
        string_to_use=""
        return string_return

    if("." in s):
        list_of_numbers=s.split(".")
        for character in list_of_numbers:
            string_to_use+=character
        string_return=string_to_use
        string_to_use=""
        return string_return
    else:return s

credit_card=[]
credit_card_sum=[]
credit_card_sum_digit=[]
credit_digits_sum=0

user1_input=input()
user_input=checker(user1_input)
while user1_input!="end" and user1_input!="END":
    user_input=checker(user1_input)
    if( not user_input.isdigit()):
        print("False")
    elif(user_input.isdigit() and len(user_input)>16):
        print("False")
    else:
        credit_card_int=[int(x) for x in user_input]
        if credit_card_int[0]<4 or credit_card_int[0]>=7:
          print ("False")
        else:
          for i in range(0,len(credit_card_int),2):
              credit_card_int[i] = credit_card_int[i]*2
          digit_sum(credit_card_int)
          for i in range(len(credit_card)):
            credit_digits_sum=credit_digits_sum+credit_card[i]
          if credit_digits_sum %10 ==0:
             print ("True")
          else:
            print ("False")
    user1_input=input()

but outputs wrong bool with input 54 97357 170632 130

[frequency]

done

def checker(s):
    list_of_numbers=[]
    string_to_use=""
    if("-" in s):
        list_of_numbers=s.split("-")
        for character in list_of_numbers:
            string_to_use+=character
        string_return=string_to_use
        string_to_use=""
        return string_return
    if(" " in s):
        list_of_numbers=s.split(" ")
        for character in list_of_numbers:
            string_to_use+=character
        string_return=string_to_use
        string_to_use=""
        return string_return
    if("," in s):
        list_of_numbers=s.split(",")
        for character in list_of_numbers:
            string_to_use+=character
        string_return=string_to_use
        string_to_use=""
        return string_return
    if("*" in s):
        list_of_numbers=s.split("*")
        for character in list_of_numbers:
            string_to_use+=character
        string_return=string_to_use
        string_to_use=""
        return string_return

    if("." in s):
        list_of_numbers=s.split(".")
        for character in list_of_numbers:
            string_to_use+=character
        string_return=string_to_use
        string_to_use=""
        return string_return
    else:
        return s

credit_card=[]
credit_card_sum=[]
credit_card_sum_digit=[]
credit_digits_sum=0

user1_input=input()
user_input=checker(user1_input)
check=False
while user1_input!="end" and user1_input!="END":
    user_input=checker(user1_input)
    if(len(user1_input)>16):
        if(len(user1_input)!=19):
            print("False")
            user1_input=input()
            continue
        elif(user1_input[4].isdigit() or user1_input[9].isdigit() or user1_input[14].isdigit()):
                print("False")
                user1_input=input()
                continue
    if( not user_input.isdigit()):
        print("False")
    elif(user_input.isdigit() and len(user_input)!=16):
        print("False")
    else:
        credit_card_int=[int(x) for x in user_input]
        if credit_card_int[0]<4 or credit_card_int[0]>7:
            print ("False")
        else:
            for i in range(0,len(credit_card_int),2):
                credit_card_int[i] = credit_card_int[i]*2
                if credit_card_int[i]>=10:credit_card_int[i]= (int(str(credit_card_int[i])[0])+int(str(credit_card_int[i])[1]))
            if (sum(credit_card_int) % 10 ==0):
                print ("True")
            else:
                print ("False")
    user1_input=input()