Change value of global variable input into a defined function

Question

I want function(x) to change the value of whatever global variable is put into it, say add one to the variable, like so:

>>> a = 1
>>> function(a)
>>> print(a)
2

I tried:

def function(x):
    global x
    x = x + 1

However, this returns a SyntaxError name 'x' is parameter and global...

"change the value of whatever global variable is put into it"—This is not possible. The function does not receive the variable used when calling it. It only receives the value. — khelwood, Jul 22 '20 at 10:10
it doesn't really make sense to pass the variable as an argument and also expect to change it in the local namespace. — Vishal Singh, Jul 22 '20 at 10:11
You have an issue here because numbers are immutable, they are not modified, variables end up pointing to a different number, so if you have a variable pointing to a number you won't be able to change that number. There may be a deep way of modifying directly which memory direction a variable is pointing to but I would suggest you stay away from that — Adirio, Jul 22 '20 at 10:11
There is one way this could be done if passing the variable name (`'x'`) instead of the variable itself(`x`): You can achieve this if you pass the variable name instead of the variable: `def function(var): globals()[var] += 1` — Adirio, Jul 22 '20 at 10:23

score 0 · Answer 1 · answered Jul 22 '20 at 10:10

0

a=1 #global variable
def function():
    global a
    a=a+1 #operation on variable a
    return a
function()

is this answer your query?

answered Jul 22 '20 at 10:10

user13966865

Sorry, no. I said "whatever" global variable, hence I need the function to work for any variable put into it, not just 'a'. – aanonym Jul 22 '20 at 10:12

1 Answers1