Order of evaluation >> and [++]

Question

I have a question about the precedence in an operation in C++. I have search for precedence in http://en.cppreference.com/w/cpp/language/operator_precedence and I read this question that is more or less the same array increment difference in C

I didn't get any clear conclusion. If I do

var >> array[n++];

Operator >> is for stream that is reading chars. ¿Where it is stored what I read? In n or in n+1?

Thank you

Order of evaluation and precedence are completely different concepts, neither one relevant to your question. — molbdnilo, Dec 15 '15 at 10:10

score 8 · Accepted Answer · answered Dec 15 '15 at 10:03

8

This isn't really to do with precedence, it's to do with the semantics of post-increment.

var >> array[n++];

n++ will increment n and evaluate to the original value of n. As such, it's equivalent to writing:

var >> array[n];
++n;

So the value will be read into array[n].

answered Dec 15 '15 at 10:03

TartanLlama

Or ... *the value will be read into **array[n-1]** if you take n to be the after-the-statement value* – Nawaz Dec 15 '15 at 10:11

score 4 · Answer 2 · edited May 23 '17 at 12:30

4

It is stored in n. n++ increments the counter and returns the old value. ++n increments the counter and returns the new value.

edited May 23 '17 at 12:30

Community

answered Dec 15 '15 at 09:58

Houbie

5

And you should note that this isn't an operator precedence issue. It is an order of evaluation issue. – user207421 Dec 15 '15 at 10:01

2 Answers2