我是初学者Python学习者，我正在研究Luhn算法来检查信用卡验证。我编写了大部分代码，但是我遇到了2个错误，我得到的第一个是在分配之前引用了num。我得到的第二个是'_io.TextIOWrapper'类型的对象没有len（）。将非常感谢进一步的帮助/指导。
以下是Luhn算法（Mod10检查）的步骤
这是我的输出应该是什么
Card Number Valid / Invalid
--------------------------------------
3710293 Invalid
5190990281925290 Invalid
3716820019271998 Valid
37168200192719989 Invalid
8102966371298364 Invalid
6823119834248189 Valid
这是代码。
def checkSecondDigits(num):
length = len(num)
sum = 0
for i in range(length-2,-1,-2):
number = eval(num[i])
number = number * 2
if number > 9:
strNumber = str(number)
number = eval(strNumber[0]) + eval(strNumber[1])
sum += number
return sum
def odd_digits(num):
length = len(num)
sumOdd = 0
for i in range(length-1,-1,-2):
num += eval(num[i])
return sumOdd
def c_length(num):
length = len(num)
if num >= 13 and num <= 16:
if num [0] == "4" or num [0] == "5" or num [0] == "6" or (num [0] == "3" and num [1] == "7"):
return True
else:
return False
def main():
filename = input("What is the name of your input file? ")
infile= open(filename,"r")
cc = (infile.readline().strip())
print(format("Card Number", "20s"), ("Valid / Invalid"))
print("------------------------------------")
while cc!= "EXIT":
even = checkSecondDigits(num)
odd = odd_digits(num)
c_len = c_length(num)
tot = even + odd
if c_len == True and tot % 10 == 0:
print(format(cc, "20s"), format("Valid", "20s"))
else:
print(format(cc, "20s"), format("Invalid", "20s"))
num = (infile.readline().strip())
main()
答案 0 :(得分：1)
你忘了初始化num
def main():
filename = input("What is the name of your input file? ")
infile= open(filename,"r")
# initialize num here
num = cc = (infile.readline().strip())
print(format("Card Number", "20s"), ("Valid / Invalid"))
print("------------------------------------")
while cc!= "EXIT":
even = checkSecondDigits(num)
odd = odd_digits(num)
c_len = c_length(num)
tot = even + odd
if c_len == True and tot % 10 == 0:
print(format(cc, "20s"), format("Valid", "20s"))
else:
print(format(cc, "20s"), format("Invalid", "20s"))
num = cc = (infile.readline().strip())
答案 1 :(得分：0)
这是一个基于lunh算法
的非常简单的代码版本def validator(n):
validatelist=[]
for i in n:
validatelist.append(int(i))
for i in range(0,len(n),2):
validatelist[i] = validatelist[i]*2
if validatelist[i] >= 10:
validatelist[i] = validatelist[i]//10 + validatelist[i]%10
if sum(validatelist)%10 == 0:
print('This a valid credit card')
else:
print('This is not valid credit card')
def cardnumber():
result=''
while True:
try:
result = input('Please enter the 16 digit credit card number : ')
if not (len(result) == 16) or not type(int(result) == int) :
raise Exception
except Exception:
print('That is not a proper credit card number. \nMake sure you are entering digits not characters and all the 16 digits.')
continue
else:
break
return result
def goagain():
return input('Do you want to check again? (Yes/No) : ').lower()[0] == 'y'
def main():
while True:
result = cardnumber()
validator(result)
if not goagain():
break
if __name__ == '__main__':
main()
答案 2 :(得分：0)
旧线程，但答案与我有关……而真正的问题尚未确定。 实际上，错误是当在主线中调用函数时，在将checkSecondDigits定义为参数的标识符/名称时，已使用参数的标识符（num）。该函数应在main（）中通过以下方式调用 even = checkSecondDigits（cc），因此cc中的值（作为参数）被传递到num（作为参数）以在函数中使用。 相同的菜鸟错误是用奇数位和cc_length造成的。
这个问题（以及最初建议的答案）表明了将参数传递给参数的基本误解... 建议的“声明” num只是隐藏了此错误/误解，而且混淆了num（只能是本地）和cc（是全局）的局部和全局作用域，因此尽管在这种情况下建议有效，但它适用于错误的原因，糟糕的风格和不良的编程。
答案 3 :(得分：0)
进一步， num不应出现在main（）中的任何地方，因为它应该是局部的（仅出现在被称为...的函数内部）。 该代码的最后一行应与第一行相同，但是最后一行错误地将数据分配给num而不是cc
cc = (infile.readline().strip())
print(format("Card Number", "20s"), ("Valid / Invalid"))
print("------------------------------------")
while cc!= "EXIT":
even = checkSecondDigits(num)
odd = odd_digits(num)
c_len = c_length(num)
tot = even + odd
if c_len == True and tot % 10 == 0:
print(format(cc, "20s"), format("Valid", "20s"))
else:
print(format(cc, "20s"), format("Invalid", "20s"))
num = (infile.readline().strip())
答案 4 :(得分：0)
您可以使用我的代码进行卡验证，因为卡结构存储在CSV文件中，所以它是100％动态的，因此此处GitHub profile，python file link上的代码很容易更新， code explanation file link和CSV for datafile link
python代码：
# -*- coding: utf-8 -*-
"""
Created on Tue Sep 10 20:55:30 2019
@author: Preyash2047@gmail.com
"""
import csv
import numpy as np
#csv file imported and storf in reader
reader = csv.DictReader(open("card_data.csv"))
#input card number
card_number = input("Enter the card No: ")
#global variable declaration
min_digits=0
max_digits=0
card_number_list = list(card_number)
card_number_list_reverse=card_number_list[::-1]
card_number_length=len(card_number_list)
first_digit = int(card_number_list[0])
#global variable for final output
card_provider_list_number = 0
result_found = False
card_number_digits = 0
mit_name=""
#list
start=[]
end=[]
name=[]
c_d=[]
number_length=[]
min_max_digits_list=[]
#append the list from csv
for raw in reader:
start.append(raw['start'])
end.append(raw['end'])
name.append(raw['name'])
c_d.append(raw['c_d'])
number_length.append(raw['number_length'])
#initialize the value of min_digits & max_digits
def min_max_digits():
global min_digits
global max_digits
for i in range(len(start)):
available_length=number_length[i].split(',')
for j in range(len(available_length)):
min_max_digits_list.append(available_length[j])
min_max_digits_array = np.array(min_max_digits_list)
np.unique(min_max_digits_array)
min_digits=int(min(min_max_digits_array))
max_digits=int(max(min_max_digits_array))
#list to int
def list_to_int(noofdigits):
str1 = ""
return int(str1.join(noofdigits))
#card validation
def iin_identifier():
first_six_digit = list_to_int(card_number_list[0:6])
for i in range(len(start)):
if(first_six_digit >= int(start[i]) and first_six_digit <= int(end[i])):
available_length=number_length[i].split(',')
for j in range(len(available_length)):
if(card_number_length == int(available_length[j])):
global card_provider_list_number
card_provider_list_number = i
global card_number_digits
card_number_digits = available_length[j]
global result_found
result_found = True
#Major Industry Identifier (MII) identification
def mit_identifier():
global first_digit
global mit_name
switcher = {
1: "Airlines",
2: "Airlines",
3: "Travel and Entertainment",
4: "Banking and Financial Services",
5: "Banking and Financial Services",
6: "Merchandising and Banking",
7: "Petroleum",
8: "Health care, Telecommunications",
9: "National Assignment"
}
mit_name=switcher.get(first_digit, "MIT Identifier Not Found")
#Luhn Algorithm or modulo-10 Algorithm
def luhn_algorithm():
for i in range(card_number_length):
if(i%2!=0 and i!=0):
card_number_list_reverse[i]=int(card_number_list_reverse[i])*2
#print(str(i)+" "+ str(card_number_list_reverse[i]))
if(len(str(card_number_list_reverse[i]))==2):
even_number_2=list(str(card_number_list_reverse[i]))
card_number_list_reverse[i] = int(even_number_2[0])+int(even_number_2[1])
#print("\tsubsum "+str(i)+" "+str(card_number_list_reverse[i]))
else:
card_number_list_reverse[i]=int(card_number_list_reverse[i])
division_int = int(sum(card_number_list_reverse)/10)
division_float=sum(card_number_list_reverse)/10
if(division_int-division_float==0):
return True
#initial level number length validation
def card_number_validation():
min_max_digits()
if(card_number_length>= min_digits and card_number_length <= max_digits and first_digit != 0):
iin_identifier()
mit_identifier()
if(result_found and luhn_algorithm()):
print("\nEntered Details are Correct\n")
print("\nHere are the some details we know about you card")
print("\nNo: "+card_number)
print("\nIssuing Network: "+name[card_provider_list_number])
print("\nType: "+c_d[card_provider_list_number]+" Card")
print("\nCategory of the entity which issued the Card: "+mit_name)
else:
print("\nCard Number is Invalid\nPlease renter the number!\n")
else:
print("\nCard Number is Invalid\n")
#method called to run program
card_number_validation()
答案 5 :(得分：0)
n = input("Enter 16-digit Credit Card Number:")
lst = []
for i in range(16):
lst.append(n[i])
# print(lst)
# list1 = n.split()
# print(list1)
def validate_credit_card():
global lst
if len(lst) == 16:
for i in range(0, len(lst)):
lst[i] = int(lst[i])
# print(lst)
last = lst[15]
first = lst[:15]
# print(first)
# print(last)
first = first[::-1]
# print(first)
for i in range(len(first)):
if i % 2 == 0:
first[i] = first[i] * 2
if first[i] > 9:
first[i] -= 9
sum_all = sum(first)
# print(first)
# print(sum_all)
t1 = sum_all % 10
t2 = t1 + last
if t2 % 10 is 0:
print("Valid Credit Card")
else:
print("Invalid Credit Card!")
else:
print("Credit Card number limit Exceeded!!!!")
exit()
if __name__ == "__main__":
validate_credit_card()
答案 6 :(得分：-1)
首先，也许您应该删除多余的字符：
def format_card(card_num):
"""
Formats card numbers to remove any spaces, unnecessary characters, etc
Input: Card number, integer or string
Output: Correctly formatted card number, string
"""
import re
card_num = str(card_num)
# Regex to remove any nondigit characters
return re.sub(r"\D", "", card_num)
使用Luhn算法检查信用卡是否有效后：
def validate_card(formated_card_num):
"""
Input: Card number, integer or string
Output: Valid?, boolean
"""
double = 0
total = 0
digits = str(card_num)
for i in range(len(digits) - 1, -1, -1):
for c in str((double + 1) * int(digits[i])):
total += int(c)
double = (double + 1) % 2
return (total % 10) == 0