I was learning precedence rule in C++. In which conditional operator is said to have Right to Left associativity. I interpret this as evaluation of expression start from right and proceed to left. So, for the below code-
int a=1, b=2, c;
c=a>b? a=a*2: a=a+3;
cout<<c<<" "<<a;
I assume output as
8 8
But actual output is
4 4
I don't understand how actually this associativity works, because from the above output it seems to me conditional operator have left to right associativity.
Associativity tells you what happens if you have multiple instances of the same operator in a row. For example,
f() - g() - h()
parses as
(f() - g()) - h()
and not
f() - (g() - h())
because - is left associative, not right associative.
None of this has anything to do with evaluation order, which determines which function is called first.
As for ?: being right associative, it means
a ? b : c ? d : e
parses as
a ? b : (c ? d : e)
(This makes slightly more sense if you think of ?...: as a single operator.)
However, ?: guarantees left-to-right evaluation: The first operand is always evaluated first, then exactly one of the other operands (depending on the truth value of the first result).
In your example,
c=a>b? a=a*2: a=a+3
(please never put assignments inside ?: like that in real code) is parsed as
c = ((a>b) ? (a=a*2) : (a=a+3))
This is entirely due to precedence, not associativity (we don't have multiple identical operators next to each other here).
a>b is evaluated first (yielding false), which causes a=a+3 to be evaluated (yielding 4), which is then assigned to c.