Computer Science Canada

Undefined variable
Author:  noelb6 [ Tue Sep 20, 2011 8:17 pm ]
Post subject:  Undefined variable
So I just started python today for a class, and I defined my variables. But when I run the program it says that the variable isn't defined.
How can I fix this?
Author:  Tony [ Tue Sep 20, 2011 8:36 pm ]
Post subject:  RE:Undefined variable
Likely a scope issue. A variable with the same name might be defined elsewhere, but it's not visible from where you are trying to use it. E.g. code inside one function doesn't see local variables defined in another function.
Author:  noelb6 [ Tue Sep 20, 2011 8:40 pm ]
Post subject:  RE:Undefined variable
it says "line 15, in <module>
while i == 0:
NameError: name 'i' is not defined"

But i have it define before that and i tried erasing it and it still didnt work
Author:  Tony [ Tue Sep 20, 2011 8:44 pm ]
Post subject:  RE:Undefined variable
in the little amount of code that you've shared, I don't see you defining that variable.
Author:  noelb6 [ Tue Sep 20, 2011 8:50 pm ]
Post subject:  RE:Undefined variable
That;s what the error said
But I defined i = 0 before
Author:  Tony [ Tue Sep 20, 2011 9:03 pm ]
Post subject:  RE:Undefined variable
post the code.
Author:  noelb6 [ Tue Sep 20, 2011 9:13 pm ]
Post subject:  RE:Undefined variable
def main():
print("This program prints out the 978th prime number")
x = 1
p = 0
z = 1
i = 0
while p < 978:
while i == 0:
if x % z == 0:
i = 1
if z == x/2:
i = 2
else:
i = 0
z = z + 1
if i == 1:
print x, "is a composite"
else:
print x, "is a prime"
p = p + 1
Author:  noelb6 [ Tue Sep 20, 2011 9:15 pm ]
Post subject:  RE:Undefined variable
main()
Author:  Tony [ Tue Sep 20, 2011 9:17 pm ]
Post subject:  Re: RE:Undefined variable
Python is indentation sensitive; they define blocks.

code:
def main():
    print("This program prints out the 978th prime number")
    x = 1
    p = 0
    z = 1
    i = 0
while p < 978:
 while i == 0:
    if x % z == 0:
        i = 1
    if z == x/2:
        i = 2
    else:
        i = 0
        z = z + 1
    if i == 1:
        print x, "is a composite"
    else:
        print x, "is a prime"
        p = p + 1

i is defined and is local to main().

your while loops are outside of main.

code inside while loops can't see what's defined inside of main.
Author:  noelb6 [ Tue Sep 20, 2011 9:23 pm ]
Post subject:  RE:Undefined variable
how do i fix that?
Author:  Tony [ Tue Sep 20, 2011 9:27 pm ]
Post subject:  RE:Undefined variable
Have them all in the same scope http://en.wikipedia.org/wiki/Scope_(computer_science)

The easiest way would be to simply place your while loops inside of main().
Author:  noelb6 [ Wed Sep 21, 2011 10:54 am ]
Post subject:  RE:Undefined variable
That worked, thank you.
Now time to fix my loops x.x

:


You can syndicate this boards posts using the file backend.php or view the topic map using sitemap.php.

Terms of Use | Privacy Policy