----- Message from [EMAIL PROTECTED] ---------
Date: Sun, 24 Aug 2008 01:31:28 -0500
From: Alberto Perez <[EMAIL PROTECTED]>
Reply-To: Alberto Perez <[EMAIL PROTECTED]>
Subject: [Tutor] hi...
To: tutor@python.org
run a program in interactive mode, the program run very good, but if
run in not interactive mode not show me error, but the return of
function returns no value, this is the source code:
def suma(no1,no2): total=no1+no2
return total
print 'hola'
opcion=input()
if opcion==1:
print 'suma'
a=input() b=input()>
suma(a,b)
the result of this code is:
hola
1
suma
5
7
total
Traceback (most recent call last): File "<pyshell#0>", line 1, in
<module> totalNameError: name 'total' is not defined>>>
why this happens??? what I did wrong??? and why run very good in
Hi,
Welcome to python and the tutor list.
An earlier response pointed out that you need to bind the returned
value to total as in
total = suma(a, b)
but I thought a bit of explanation might help. In your function, you
define total. That makes `total' a name in the scope of the function.
That means that `total' can be seen by code in your function, but not
code outside of your function.
This might seem confusing now, but in the long run, it makes life
easier. How? Well, you can define all sorts of names in the body of
your functions without having them clutter up the name-space of your
overall code. That makes things cleaner. It also makes them less error
prone. If total defined in your function was visible everywhere by
default, then you would have to make sure that your function didn't
define any names that higher level code did. (You'd have to make sure
that total defined in a function didn't overwrite total defined
outside of the function.)
You can make names defined in functions be globally available, but
until you've got some experience, don't do that. (Arguably, once you
have experience, don't do that then either ;-)
Hope that helps some,
Brian vdB
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