Use of sizeof without parenthesis

Question

I have seen use of size of operator without parenthesis.

For example

int x,y;
y = sizeof x;

what is the difference between sizeof(x) and sizeof x?
And why sizeof int does not work like sizeof(int)?

See [What does sizeof without () do?](http://stackoverflow.com/q/18898736/1708801) — Shafik Yaghmour, Sep 04 '15 at 14:53
@ShafikYaghmour I don't think anyone would have blamed you for closing that yourself. — Baum mit Augen, Sep 04 '15 at 14:55
Ahh.. self answer, eh? But the issue is, this is not a better version of the dupe, tough luck, I'd say. :) — Sourav Ghosh, Sep 04 '15 at 14:56
Ditto @BaummitAugen. (I was actually surprised to see the question was open, after SY posted the dupe. :) ) — Sourav Ghosh, Sep 04 '15 at 14:58
Found answer from another link. Just thought it could be useful for others :) — Sreeyesh Sreedharan, Sep 04 '15 at 15:10

score 0 · Answer 1 · answered Sep 04 '15 at 14:54

Since sizeof is a unary operator, it can be used before any variable or constant just like the unary operator '-' and typecast operator. So the parenthesis is not necessary if it is used with a variable or constant.

Just like -1 and -(1) work.

But if it is used with a data type, missing the parenthesis will give compiler error.

Use of sizeof without parenthesis

1 Answers1