How to determine when input is alphabetic?

Question

I been trying to solve this one for a while and can't seem to make it work right.. here is my current work

while True:

    guess = int(raw_input('What is your number?'))

    if 100 < guess or guess < 1:
        print '\ninvalid'

    else:
        .....continue on

Right now I have made it so when a user input a number higher than 100 or lower than 1, it prints out "invalid". BUT what if i want to make it so when a user input a string that is not a number(alphabetic, punctuation, etc.) it also returns this "invalid" message?

I have thought about using if not ...isdigit(), but it won't work since I get the guess as an interger in order for the above range to work. Try/except is another option I thought about, but still havent figured out how to implement it in correctly.

Answer 1

You can use exception handling:

try:
    guess = int(raw_input('What is your number?'))
    if not (1 <= guess <= 100):
        raise ValueError
    # .....continue on
except ValueError:
    print '\ninvalid'

That way, \ninvalid will be printed if the user either inputs a non-numeric string or inputs a numeric string greater than 100 or smaller than 1.

EDIT: Okay, I submit to the x < y < z syntax. Still think it loses some of its charm when it's used with not, though.

Answer 2

while True:
  try:
    guess = int(raw_input("..."))
  except EOFError:
    print "whoa nelly! EOF? we should probably exit"
    break  # or sys.exit, or raise a different exception,
    # or don't catch this at all, and let it percolate up,
    # depending on what you want
  except ValueError:
    print "illegal input: expected an integer"
  else:
    if not (1 <= guess <= 100):
      print "out of range"
    else:
      print "processing guess... (but if it wasn't 42, then it's wrong)"
      break  # out of while loop after processing