In such case:
int x=0;
(x)=5;
Why is (x) a valid lvalue (and decltype((x)) gives int&)?
What do parentheses mean here? Is there any similar situation?
Asked
Active
Viewed 117 times
1
user
- 475
- 3
- 10
-
4You can also have `((((((((x)))))))) = ((((((5))))));`... – Jarod42 Sep 04 '19 at 13:07
-
@0x5453 I agree. Thanks – user Sep 04 '19 at 13:10
-
As for what `(x)` means, see: https://timsong-cpp.github.io/cppwp/expr.prim.paren – NathanOliver Sep 04 '19 at 13:17
-
1Someone was cleaning up their desk and found some spare parentheses. – Pete Becker Sep 04 '19 at 13:48
-
Heh, I only just realised the accepted answer over there is one of mine. Actually read it 3 hours ago and everything. – Lightness Races in Orbit Sep 04 '19 at 16:51
1 Answers
1
decltype(x) inspects the type of x entity. But when you put x inside parentheses, decltype have rules for deducing types for these expressions:
- if the value category of expression is xvalue, then decltype yields
T&&; - if the value category of expression is lvalue, then decltype yields
T&; - if the value category of expression is prvalue, then decltype yields
T.
João Paulo
- 6,300
- 4
- 51
- 80