title: Python: How to ignore non-letter characters and treat all alphabetic characters as lower case?
body: <p>I'm trying to make a program in Python that checks if the inputted string is in alphabetical order (abcdearian). The program needs to ignore non-letter characters and treat capital letters as lowercase letters. For example...
  abCde is abcdearian and eff!ort is abcdearian.
  Right now the program does not ignore non-letter characters, but it does treat capital letters as lowercase letters. However, I want the program to print the original input, and not the converted one. So abCde should show up as abCde (not abcde) when it is printed. Thanks for the help!</p>
  
  <pre><code>def isabcde(s):
      for i in range(len(s) - 1):
          if s[i] &gt; s[i+1]:
              return print(s, "is not abcdearian")
      return print(s,  "is abcdearian")
  
  
  while True:
      try:
          s = input("The string? ").lower()
      except EOFError:
          break
      except TypeError:
          break
      isabcde(s)
  </code></pre>