Lists acting weird , operations+ indexing=None

Question

here is my code:
a=[1,2,3,4,5]
print(a)
def add1(arg):
arg=arg+1
for i in range(len(a)):
print(a[i])
k=a[i]
a[i]=add1(k)
print(a[i])
print(a)
this should, theoretically, result in [2,3,4,5,6]
(and i dont care about efficiency, i just found this as an example)
but instead it is: [None, None, None, None, None]
Why? And how do i fix it?

Answer 1

5Just ,

after having implemented the *return* statement in the function add1(), we can additionally simplify the rest of the code, meaning the *for loop*. this would look like:

a=[1,2,3,4,5]
print(a)

def add1(arg):
return arg + 1

for i in range(len(a)):
a[i] = add1(a[i])

print(a)

Answer 2

the add1 function doesn't return a value, so it returns none by default:

def add1(arg):
return arg+1

Answer 3

Thanks everyone

Answer 4

It is because the function returns "None".
You need to include a return statement at the end of the function to return anything, otherwise it will always return None.
Here is the code with explanation.

https://sololearn.com/compiler-playground/cVF03G3wAXBt/?ref=app

Answer 5

x = [1,2,3,4,5]

def add1(n):
return n+1

for i,v in enumerate(x):
x[i] = add1(v)

print(x)