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From: murphy@newton.physics.purdue.edu (William J. Murphy)
Newsgroups: comp.sys.amiga.tech
Subject: What's an APTR, BPTR?
Message-ID: <3421@newton.physics.purdue.edu>
Date: 7 Apr 90 16:00:09 GMT
Reply-To: murphy@newton.physics.purdue.edu.UUCP (William J. Murphy)
Distribution: comp.amiga.tech
Organization: Purdue Univ. Physics Dept., W. Lafayette, IN
Lines: 42


I was trying to play with a bit of code which would read from stdin and
then use the parallel.device to output what was read.  I came across an APTR
and can't seem to find out what exactly is an APTR.  For that matter, what's
a BPTR.  I would have to assume that APTR = Amiga Pointer = 32bit pointer?
BPTR = BCPL pointer = long-word aligned pointer.

I want to read the data from stdin into a character buffer and be able to
point the APTR to the start of this buffer and use the data contained
therein to be output to the parallel.device.

I tried something like this:

APTR printbuffer;
char *address;

main()
{
    address = (char *)AllocMem(256, MEMF_FAST);
    if (address == NULL)
        exit(99);

    scanf("%s", address);
    printbuffer = (APTR)address;
/* bunch of parallel.device code from RKM Libs and Devs example parallel.c
   deleted to make this short.*/

    ParallelIO->IOPar.io_Data = (APTR)printbuffer;
    SendIO( ParallelIO );
}

I have tries this where I have made printbuffer = (APTR)"Let the printer type
this" instead of trying to assign/cast the pointer to the beginning of
the character buffer.  It worked.  But the above example with the cast
doesn't.  I figure that I must not understand what an APTR is.

Thanks for any pointers, 8^)

-- 
Bill Murphy                                  | Zaphod, Vell he's just zis
murphy@newton.physics.purdue.edu             | guy you know.
Amiga, it's not a religion, it's a lifestyle |