Help understanding list operatoins inside functions in python 3

Laurent Pointal laurent.pointal at laposte.net
Tue Jan 13 14:43:28 CET 2015


Hello,

stephen.boulet at gmail.com wrote:

> I'm a bit confused why in the second case x is not [1,2,3]:
> 
> x = []
> 
> def y():
>     x.append(1)
> 
> def z():
>     x = [1,2,3]

Here x is a local, so global x is not modified.
If you want to modify gobal x, write:
def z():
    global x
    x = [1,2,3]

You can read the Python FAQ about global/local rules:

https://docs.python.org/3/faq/programming.html#what-are-the-rules-for-local-and-global-variables-in-python

Or Dive Into Python

http://www.diveintopython.net/html_processing/locals_and_globals.html

(and for your problem, its the same with Python2 and Python3)

Or…

A+
Laurent.



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