In answering this question the question arose as to whether the traditional C meaning of the keyword auto (automatic storage) is still valid in C++0x now that it means type deduction.
I remember that the old meaning of auto should remain where relevant but others disagreed.
auto char c = 42; // either compilation error or c = '*'
Looking at compilers I see the current division.
- Old meaning of auto is no longer allowed
- VS10
- g++
- Old meaning of auto is used where relevant
Do you know which is the correct behaviour?
No, it is not. In fact, §7.1.6.4/3 gives the following example:
auto x = 5; // OK: x has type int
const auto *v = &x, u = 6; // OK: v has type const int*, u has type const int
static auto y = 0.0; // OK: y has type double
auto int r; // error: auto is not a storage-class-specifier
As you can see, it results in an error. §7.1.6.5 pretty much seals the deal with:
A program that uses auto in a context not explicitly allowed in this section is ill-formed.
来源：https://stackoverflow.com/questions/2847734/is-auto-int-i-valid-c0x