title: Code python to check credit card and bank
body: <p>I'm working on a small script to check credit cards and bank validity but for a crazy reason I get an error I do not understand.</p>
  
  <pre><code>#!/usr/bin/python
  # -*- coding: utf-8 -*-
  def digitSum(myString):
  
      length = len(myString)
      oddSum = 0
      evenSum = 0
  
      #base case
      if (length ==0):
          return 0
  
      #length &gt; 0
      else:
          #if even
          if (length % 2 ==0):
              last = int(myString[-1])
              evenSum += last
  
              return evenSum + digitSum(myString[:-1])
  
          else:
              last = int(myString[-1])
              last = 2 * last
              part_sum = last // 10 + last % 10
              oddSum += part_sum
  
              return oddSum + digitSum(myString[:-1])
  
  
  def luhns():
      myString = input("Entrez les 16 numéros de la Carte de Crédit ")
  
      total = digitSum(myString)
      if (total % 10 == 0):
  
          if total[:1] == "4":
              cardtype = "Visa"           
          if int(total[:2]) &gt;= 51 and int(total[:2]) &lt;= 55:
              cardtype = "Master Card"
          if total[:2] == "34" or total[:2] == "37":
              cardtype = "American Express"
          if total[:4] == "6011":
              cardtype = "Discover"
          if total[:2] == "36":
              cardtype = "DINERS"
          if int(total[:3]) &gt;= 300 and int(total[:3]) &lt;= 305:
              cardtype = "DINERS"
  
          return cardtype
  
          print ('Carte valide') + cardtype
      else:
          print ('Carte invalide')
  
  
  def main():
      luhns()
  
  #Python call to main()
  main()
  </code></pre>
  
  <p>This is the error I'm getting:</p>
  
  <pre class="lang-none prettyprint-override"><code>Entrez les 16 numéros de la Carte de Crédit 11111
  Traceback (most recent call last):
    File "/Volumes/Python/LuhnsAlgorithm.py", line 61, in &lt;module&gt;
      main()
    File "/Volumes/Python/LuhnsAlgorithm.py", line 58, in main
      luhns()
    File "/Volumes/Python/LuhnsAlgorithm.py", line 34, in luhns
      total = digitSum(myString)
    File "/Volumes/Python/LuhnsAlgorithm.py", line 5, in digitSum
      length = len(myString)
  TypeError: object of type 'int' has no len()
  logout
  </code></pre>