While listening to John Gardeniers Pete heard:Bad habits & file moving

G'day John

 JG> #define NULL  0

 PC> Shouldn't NULL be defined for you in a header file somewhere.?
 PC> I'm not sure what compiler your using so maybe not.

 JG> I use PCC and to keep the speed up, as much as practical (I use
 JG> an XT to do my programming), I avoid header files.  PCC is quite
 JG> different to other compilers in as much as prototyping is rarely
 JG> needed and almost everything that's a standard macro on another
 JG> compiler is a function with PCC.

Why not look around for a 2nd hand copy of Quick C 2.5, it runs on an
XT and would be a step up from PCC 

 JG> #define TRUE  0
 JG> #define FALSE !TRUE
~~~   ^^^^^^^^^^^^^^^^^^
 PC> I think defining FALSE to a non-zero value would be a bad habit
 PC> to get into, it would be better to always assume FALSE to be
 PC> zero.

 JG> One thing in favour of having TRUE=0 is that on a no error
 JG> completion of a function you can simply "fall through" at the
 JG> end, i.e.  no explicit RETURN.  I personally like using non-zero
 JG> far FALSE as it allows me to test for FALSE and then act
 JG> acording to what value was actually returned, much like DOS
 JG> error levels.

Your relying on your compiler to clear AX for you on returning from a
function, you must also have the warnings threshhold set low as my
compiler (QC) generates a warning if i forget to add a 'return n;' in
functions that return a value.

 JG> From your other reply:

 JG> Next project: How to do a move without a copy if the destination
 JG> is the same drive as the source.  That would save quite a bit of
 JG> time with large files. Any thoughts?

 PC> Quite simple use the rename() function, see info below.

 JG> This was actually the very first thing I tried.  Both DOS
 JG> (command line) and PCC failed to move the file, so I started
 JG> searching for another way.  On reading your reply I tried again
 JG> with the same results.  I then tried going straight to DOS,
 JG> using assembler and AH=56H INT 21H...Bingo!

Your right it would be quite easy.

int renamefile(char _far * oldfile, char _far * newfile) {

int retval = 0;

    _asm {
    lds   dx, oldfile
    les   di, newfile
    mov   ah, 56h
    int   21h
    jnc   a
    mov   retval, ax
  a:
    }

    return retval;
}

 JG> I hope you feel good about me throwing away a couple of days of
 JG> work, tracing directory entries, FATs, etc.  .  At least my
 JG> code can now shrink by about 4 or 5 Kb and I now know a lot more
 JG> about how everything on a disk is organised.

Hehe it's what i do best, I Better go buy some more spanners :-) 

 JG> Thank for you comments, as well as getting me back on the right
 JG> track with the file move.

no problem.

   -=Pete=-


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