right associativity and order of execution of nested ternary operator in c++

Question

I have the solution regarding execution order, but I cant understand how right associativity is linked to SCENARIO 2.

a ? b: c ? d : e ? f : g ? h : i // scenario 1 : associativity understood, which is : (a?b:(c?d:(e?f:(g?h:i))))

and

a ? b ? c : d : e // scenario 2 : NOT UNDERSTOOD

From the first answer here, I am able to understand the first scenario but not the second.

Answer 1

The obvious (and generally best) advice about things like this is "just don't do it."

Other than that, I find the easiest approach to be to think of them like Algol-style ifs. An Algol if was an expression, not a statement, so (much like a conditional, except readable) you could write something like this:

a = if b then c else d;

The transformation is really pretty simple. x ? is if (x) and : is else. Applying this to a nested conditional is actually pretty easy, and at least in my opinion, the result is much more readable.

a ? b: c ? d : e ? f : g ? h : i

Transforms to:

if (a) {
    b; 
} else if (c) {
    d; 
} else if (e) {
    f;
} else if (g) {
    h;
} else {
    i;
}

The second is actually just about as easy, as long as you remember that x ? translates directly to if (x). Other than that, we follow the normal C rule that an else matches up with the most recent if that doesn't already have an else associated with it.

a ? b ? c : d : e

...becomes:

if (a) {
    if (b) {
        c;
    }
    else {
        d;
    }
} else {
    e;
};