Pointer to String chars - Everett style

re: Pointer to String chars - Everett style

Garrett Serack — Tue, 23 Dec 2003 16:33:00 GMT

Sweet Mother Of all that is Good and Holy.

#include <vcclr.h>

I'm a little unclear how that escaped me all this time--Probably 'cause I neglected to read any documentation when Everett came out, I just upgraded and moved on. I don't mind wchar_t* 's : It's what I wanted all along.

*sigh* -- Must be a sign to find a complete management job :)

Yeah, pin pointers rock. :) -- And you sure are correct about the need to use them as little and quickly as possible.

I've been pretty strict about their usage, just to be safe. I typically have built a few macros/inline functions to handle pinning, to guarantee they have limited lifespan.

Now, I just looked at the vcclr.h file.

inline const System::Char * PtrToStringChars(const System::String *s) {

const System::Byte *bp = reinterpret_cast<const System::Byte *>(s);
if( bp != 0 ) {
unsigned offset = System::Runtime::CompilerServices::RuntimeHelpers::OffsetToStringData;
bp += offset;
}
return reinterpret_cast<const System::Char*>(bp);
}

I considered doing something like that by hand, as a method of finding the beginning of the string, but I discarded the thought, as I wasn't sure if the offset into the class would be constant, and didn't want to risk buggering up in future CLR versions. Sure nice of there to be a constant declared for that :)

G

re: Pointer to String chars - Everett style

arich — Tue, 23 Dec 2003 16:40:00 GMT

Yeah, I'm actually not sure if the offset into the class is a constant or not, as the function uses the OffsetToStringData method of the runtime.

Upon ildasming mscorlib.dll (which everyone should do from time to time, just to see what's in it), it looks as though the offset is 12 - but this probably varies by architecture.

re: Pointer to String chars - Everett style

Garrett Serack — Tue, 23 Dec 2003 17:52:00 GMT

Speaking of ildasm -- I was thinking that it'd be nice if some of these type utilities were built into Visual Studio. I'm trying to do mentoring on the finer points of software devleopment with some folks and I find that they are less likely to use tools that are external to the development environment. (*sigh*--kids these days ;)

That, and developer MSIL support in VS.NET would be nice too.

Heck, while I'm at it, can I get a pony?

Garrett

Pinning Pointers

I Love that New Syntax Smell — Fri, 27 Aug 2004 20:32:00 GMT

Easily passing Managed strings to Unmanaged code (round 2)

Mike Stall's .NET Debugging Blog — Mon, 14 Feb 2005 21:58:00 GMT

Easily passing Managed strings to Unmanaged code (round 2)

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Pinning Pointers

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Hot on the heels of my article on interior pointers, comes a much more insightful one by Stan Lippman...

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