在R中更改for循环中的列表项

I used to work in C++ and I think I am misunderstanding how for-loops (or iterations) work in R. I want to change list items in a for loop, but the for loop seems to make a temporary copy and only change that? How can I prevent this? This seems like a trivial beginners question, but I was unable to find a tutorial / question on stackoverflow about why this happens.I used to work in C++ and I think I am misunder