Python Using star (*)

Question

I am confused about using *. The first_example works, but why doesn't the second_example work?

The error states:

UnboundLocalError: local variable 'a' referenced before assignment

What can I do to fix this error?

a, b, c, d, e, f, g, h, i = range(1,10)
alphabet = [a, b, c, d, e, f, g, h, i]

def first_example(*alphabet):
    j = g + i
    print (j)
    second_example(*alphabet)

def second_example(*alphabet):
    a = a + 1
    print (a)

first_example(*alphabet)

Note that neither of your functions actually do anything with their `alphabet` parameter. The `alphabet` parameter is not involved in any way with variable lookup for `a`, `g`, `i`, or any of the other variables. — user2357112, Apr 20 '17 at 22:40
Your first_example() works because you're creating a new variable called 'j' and only reading 'g' and 'i'. But since you're trying to read _and_ modify 'a' -- not defined in the scope of your function second_example(), you'd have to add the 'global' keyword. — Abhishek Balaji R, Apr 20 '17 at 22:40
Looks like you stumbled upon python's (non-C-like) scoping rules. See: http://www.python-course.eu/python3_global_vs_local_variables.php for a good explanation — sgrg, Apr 20 '17 at 23:34

OneCricketeer · Accepted Answer · 2017-04-20T22:41:52.003

1

Not sure what you're trying to do (since alphabet parameter is unused), or why you think * is the issue, but this'll fix the problem.

def second_example(*alphabet):
    global a  # add this
    a = a + 1
    print (a)

edited Apr 20 '17 at 22:41

answered Apr 20 '17 at 22:29

OneCricketeer

179,855
19
132
245

Thanks! Simple and works like a charm! – Johnny Kang Apr 20 '17 at 22:37

Python Using star (*)

1 Answers1