What is the difference between void swap(int &,int&)and void swap (int,int)

Question

what is the use of '&' here ??

Answer 1

"address-of" operator, it's in the tutorials! ~_~ (…also, this won't work…)

Answer 2

swap(int,int) wont work.

Answer 3

some code for demo here
https://code.sololearn.com/ckFKDRje4kGV/?ref=app
:-)