Can anybody help figure what is happening?

Question

#include <iostream >
using namespace std;
int main(){
int n=4;
cout<<++n + 6*n++/2;
}
The code above keeps giving me different results in each compiler

In codebloaks and dev
The result is 21
And in visual studio 2019 and cfree
The result is 20
I even tried turbo C++ and
The result was 18

I am confused why that is ?

Answer 1

Because of Sequence point issue.
Hope this helps you....
https://www.sololearn.com/Discuss/2238290/?ref=app

edit:
pls use suitable tags like language c/c++, output, sequence point issue,...