Has a new symbol joined the C++ language specification while I was sleeping under a rock?
I just encountered the following question:
http://stackoverflow.com/questions/3621649/restrict-text-box-to-only-accept-10-digit-number-c
Which suggests that the '^' symbol is somehow part of C++ (not in the 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)
It 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. This construct is used to declare a variable somewhat similar to a pointer that can reference an object on the managed heap.
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."
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++.
The '^' syntax refers to a tracking reference in C++/CLI, a Microsoft extension to C++ which enables interaction with managed code.
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.