I just came across this code and a few Google searches turn up no explanation of this mysterious (to me) syntax.
Hashtable^ tempHash = gcnew Hashtable(iterators_);
IDictionaryEnumerator^ enumerator = tempHash->GetEnumerator();
What the heck does the caret mean? (The gcnew is also new to me, and I asked about that here.)
This is C++/CLI and the caret is the managed equivalent of a * (pointer) which in C++/CLI terminology is called a 'handle' to a 'reference type' (since you can still have unmanaged pointers).
(Thanks to Aardvark for pointing out the better terminology.)
// here normal pointer
P* ptr = new P; // usual pointer allocated on heap
P& nat = *ptr; // object on heap bind to native object
//.. here CLI managed
MO^ mngd = gcnew MO; // allocate on CLI heap
MO% rr = *mngd; // object on CLI heap reference to gc-lvalue
In general, the punctuator % is to ^ as the punctuator & is to *. In C++ the unary & operator is in C++/CLI the unary % operator.
While &ptr yields a P*, %mngd yields at MO^.
It means that this is a reference to a managed object vs. a regular C++ pointer. Objects behind such references are managed by the runtime and can be relocated in the memory. They are also garbage-collected automatically.
When you allocated managed memory, that memory can be moved around by the garbage collector. The ^ operator is a pointer for managed memory which continues to point to the correct place even if the garbage collector moves the object it points to.
In C++/CLI it means a managed pointer. You can read more about it (and other C++/CLI features) here:
From MSDN, it looks like the caret means you are getting a handle to the type being created.
It's also worth considering the following couple of sentences, that put the answer in a slightly different way:
"The handle declarator (^, pronounced "hat"), modifies the type specifier to mean that the declared object should be automatically deleted when the system determines that the object is no longer accessible."
"Because native C++ pointers (*) and references (&) are not managed references, the garbage collector cannot automatically update the addresses they point to. To solve this problem, use the handle declarator to specify a variable that the garbage collector is aware of and can update automatically."
(And "native" is I.M.H.O. a better word than 'handle', as handle is possibly a word that was brought more so in by the use of the 'Windows SDK')
