Does anybody see such an array indexing way like "2[array]"?

Question

Today, I see such a wierd way of indexing the arry.

The code is like:

int array[] = {10, 20, 30};
cout << -2[array];

I've never seen such a strange way of using array. But there is no compilation error.

Can anyone tell me does the ISO document evolve the description for this way of using array?

This is literally the second duplicate today, and the third one within two days. Can't you guys use google? — The Paramagnetic Croissant, Jun 03 '14 at 08:38
Well, acturally I did not see the duplicated one. Sorry for that. — Zavier Sheck, Jun 03 '14 at 08:39

score 3 · Answer 1 · answered Jun 03 '14 at 08:36

3

It works, because expressions of the form x[y] is just sugar for *(x+y), and of course, the addition is commutative, so 2[array] and array[2] get compiled to the same thing.

Don't do it though, because it's unnecessarily confusing.

answered Jun 03 '14 at 08:36

amnn

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Read the question again. There is `-2`. – haccks Jun 03 '14 at 08:36
2

@haccks, is not the concept is same? `a-b` is just `a+(-b)`. – Rakib Jun 03 '14 at 08:37
@RakibulHasan; Yes. But what I know is -ve index is invalid. `array[-2]` is not valid. – haccks Jun 03 '14 at 08:40
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its being applied to the result, so -array[2]. – Mike Jun 03 '14 at 08:41
@haccks, invalid index has nothing to do with compilation. – Rakib Jun 03 '14 at 08:41
@haccks I think that is an operator priority issue. – Zavier Sheck Jun 03 '14 at 08:42

Does anybody see such an array indexing way like "2[array]"?

1 Answers1