Mail Archives: djgpp/1998/12/14/08:36:59
| From: | "=?iso-8859-1?Q?Veli-Pekka_Kilpel=E4inen?=" <vpk2 AT sci DOT fi>
|
| To: | <djgpp AT delorie DOT com>
|
| Subject: | Incorrect increment?
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| Date: | Mon, 14 Dec 1998 15:34:59 +0200
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| Message-ID: | <01be2766$8b88d320$0a034ac3@vpk2.sci.fi>
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| MIME-Version: | 1.0
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| Reply-To: | djgpp AT delorie DOT com
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I don't have a C++ book so try to bear me.
I'm having a problem trying to increment a pointer of type unsigned =
char. When I use Rhide's debugger and moving step by step(F8) while =
monitoring the pointers "value" I see that instead of moving one byte =
foward, it'll go three. Here's a cutout from my file:
void movemydata(int max, unsigned char *pointertodata)
{
...
_farsetsel(_dos_ds);
for (int index =3D 0; index < max; index++)
{if ( (index & 3) =3D=3D 3)
{pointertodata++; // yes, I'm trying to skip=20
destinteger++;} // every fourth byte.
else {_farnspokeb(destinteger++, *pointertodata);
pointertodata++;} // yes, I've put it here to verify=20
}; // I'm incrementing the pointer.
...
}
It would be nice if you'd answer these too:
-Am I getting into trouble when not restoring the original selector?
-The size of variables differ from what my tutorial says - integers are =
not two bytes long. Does this depend on the enviroment? Mine is PC =
Pentium. How do I get one byte long integers?
-What will happen if I "overload" my integers trying to put too big =
number in it?
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<DIV><FONT color=3D#000000 face=3DArial size=3D2>I don't have a C++ book =
so try to=20
bear me.</FONT></DIV>
<DIV><FONT color=3D#000000 face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT color=3D#000000 face=3DArial size=3D2>I'm having a problem =
trying to=20
increment a pointer of type unsigned char. When I use Rhide's debugger =
and=20
moving step by step(F8) while monitoring the pointers "value" =
I see=20
that instead of moving one byte foward, it'll go three. Here's a cutout =
from my=20
file:</FONT></DIV>
<DIV><FONT color=3D#000000 face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT color=3D#000000 face=3DArial size=3D2>void movemydata(int =
max, unsigned=20
char *pointertodata)<BR>{<BR>...<BR>_farsetsel(_dos_ds);<BR>for (int =
index =3D 0;=20
index < max; index++)<BR> {if ( (index & 3) =3D=3D 3)<BR> =20
{pointertodata++; // yes, I'm trying to skip <BR> =20
destinteger++;} // every fourth byte.<BR> =
else =20
{_farnspokeb(destinteger++, *pointertodata);<BR> =20
pointertodata++;} // yes, I've put it here to verify <BR>=20
}; // I'm=20
incrementing the pointer.<BR>...<BR>}</FONT> </DIV>
<DIV><FONT color=3D#000000 face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT color=3D#000000 face=3DArial size=3D2>It would be nice if =
you'd answer=20
these too:<BR>-Am I getting into trouble when not restoring the original =
selector?<BR>-The size of variables differ from what my tutorial says - =
integers=20
are not two bytes long. Does this depend on the enviroment? Mine is PC =
Pentium.=20
How do I get one byte long integers?<BR>-What will happen if I=20
"overload" my integers trying to put too big number in=20
it?</FONT> </DIV></BODY></HTML>
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