# This is the user input function
# Test file
# ECS 10, May 11, 2009

# function to read and vet user selection
# returns: n, the number of tosses
# NOTE: n must be positive; return -1 to quit
def getinput():
    # loop until we get good input
    while True:
        try:
            # get the input and check the type here
            n = input("Enter the number of tosses: ")
            n += 0;
        except EOFError:        # user wants to quit, so help her
            n = -1
            break
                                # oops! let error check below do the work
                                # so set v to something illegal (not 0-3)
        except (SyntaxError, NameError, TypeError):
            n = -1
        # now check the value we read/were given
        if n > 0:
            break
        # this is bad, so say so
        print "You have to enter a positive number"

    # it's non-negative to continue, -1 to quit
    return n

# Main routine to enable us to test getinput()
def main():
    # get the input
    n = getinput()
    # loop until quit
    while n >= 0:
        # say what you got so user can check
        print "User entered", n
        # get another input
        n = getinput()
    # all done! say what user typed
    print "Quitting: n =", n

main()