Has a new symbol joined the C++ language specification while I was sleeping under a rock?
I just encountered the following question:
Restrict Text Box to only accept 10 digit number
Which suggests that the '^' symbol is somehow part of C++ (not in t开发者_如何学Che legacy meaning of a bitwise-XOR)
Is this so?
If so, what does it mean? (I tried to google the question but Google didn't come up with satisfactory answers)
In C++ the “^” symbol is the bitwise exclusive or (xor) operator. For a single bit you have 0 ^ 0 = 1 ^ 1 = 0
and 0 ^ 1 = 1 ^ 0 = 1
.
However, in the question you are refering to it is part of Microsoft special syntax for C++ development on the .NET platform known as C++/CLI or It Just Works.
Memory on .NET is garbage collected and references to objects will have to be tracked. This makes it impossible to reference these objects using a normal C++ pointer. Microsoft has decided to reuse the “^” symbol to declare a variable somewhat similar to a pointer that can reference an object on the managed heap.
^ (Handle to Object on Managed Heap)
In Visual C++, ^
represents a handle to a managed object. Essentially what in C# would be a reference. Allocate them with gcnew
instead of new
, and they will be garbage collected for you. This is how Visual C++ interacts with the CLI.
In the referenced answer, it's not part of the standard C++ language, it's part of the C++/CLI language that Microsoft cobbled together for .NET interop. In that language, ^ means a "pointer to managed memory."
The '^' syntax refers to a tracking reference in C++/CLI, a Microsoft extension to C++ which enables interaction with managed code.
It's not part of Standard C++. It's part of Managed C++ (Microsoft's language much like C++ for .NET). It means "a reference to ----" in much the same way a "*" means "A pointer to -----" is Standard C++.
精彩评论