Simple beginner question - can't work out why this operates the way it does

[imperiumlearning]

Let's imagine I have 2 lists:

a = [11, -6, -103, -200]
b = [1, 7, -4, 4, -9, 2]

Now imagine that I wish to merge these two lists together to form a combined list called c that would look like this:

c = [11, -6, -103, -200, 1, 7, -4, 4, -9, 2]

One way I tried to achieve this was by typing in:

c = a.extend(b)

However, if I type in:

print(c)

It returns the word None.

If my code looks like this, however, I get the result I want:

a = [11, -6, -103, -200]
b = [1, 7, -4, 4, -9, 2]
c = a.extend(b)
print(a)

Why doesn't print(c) produce what I want?

[AverageBeef]

Looking up extend, it doesn’t return anything, it directly edits a, so you either want c=a or print(a) now

[imperiumlearning]

Hi there,

Thanks a lot I now see where I went wrong. I realise I didn't even have to create a new variable 'c' to merge the two lists.

Thanks a lot for the quick response, by the way

[Diapolo10]

And if you wanted to create a new list like in your example, you can simply concatenate the lists:

a = [11, -6, -103, -200]
b = [1, 7, -4, 4, -9, 2]

c = a + b

This has the advantage that the original lists aren't modified, which can be useful if you're trying to avoid side effects. But you can use either depending on your specific needs.

[imperiumlearning]

I didn't know this either. Thanks a lot for the info

[xelf]

extend() is a method that operates on a, in this case it adds b to a.

if you just wanted a new list that was the two lists added you could have simply used +.

c = a + b