# average4a.py
# From Zelle's average4.py but with exception handling for no numbers input
#
# Average numbers using a sentinal loop (a while loop with a sentinal)
#   Use EOF as the sentinal (EOF is End Of File special value)
#

def main():

  sum = 0.0
  count = 0

  xStr = raw_input("Enter a number (<enter> to quit): ")  # priming the loop
  while xStr != "":
    x = eval(xStr) 
    sum = sum + x
    count = count + 1
    xStr = raw_input("Enter a number (<enter> to quit): ")

  try:
    print"\nAverage is: ", sum/count

  except ZeroDivisionError:
    print "You must enter at least one number"
    

main()