Subject: RE: unsigned char (was Examples)

>Date: Tue, 13 Jun 2000 15:23:22 -0500
>From: "Bob Crothers" <bob@cstoneindy.com>
>
>Greg,
> ...
>First, I'd recommend you use the following declaration for your space
>pointer:
>
>unsigned char *mySpacePtr;
> ...

This is interesting.  Greg, "char" is normally already an unsigned char.
If it was always true instead of just "normally" I'd say that Bob was
wrong advising you to add "unsigned" to your declaration.  But there
is a possibility of having chars default to signed by coding
  #pragma chars(unsigned)
before any other statements in the file (including directives, so
don't worry about having an include file do this pragma).

That pragma must exist because some implementations of C default char
to signed, so for portable code, I guess you should indeed specify
unsigned for bit-twiddling purposes.  (Not sure how portable your
API/user-space code needs to be though ...)

Greg, if the user-space is known to contain a particular structure, say
the return value from an API, you might as well just declare the pointer
as a pointer to that structure:

  Qus_Generic_Header_0100_t *pGenericHeader;
  QUSPTRUS (myuserspace, &pGenericHeader, &errCode);

Barbara Morris


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