问题
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.)
回答1:
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.)
回答2:
// 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^.
回答3:
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.
回答4:
When you allocated managed memory, that memory can be moved around by the garbage collector. The ^ operator is a pointer for managed memory, that continues to point to the correct place even if the garbage collector moves the object it points to.
回答5:
From MSDN, it looks like the caret means you are getting a handle to the type being created.
https://web.archive.org/web/20150117095313/http://msdn.microsoft.com/en-us/library/te3ecsc8%28VS.80%29.aspx
回答6:
In C++/CLI it means a managed pointer. You can read more about it (and other C++/CLI features) here:
http://en.wikipedia.org/wiki/C%2B%2B/CLI
回答7:
It means that it is a reference to a managed object.
来源：https://stackoverflow.com/questions/202463/what-does-the-caret-mean-in-c-cli